General And Vascular Ultrasound Clearscan

Front 1

Lon g itudinal views of the kid neys from the same patient.
1. Do these kidneys appear normal or abnormal?
2. Which is the right kidney and which is the left?
3. What are the arrows pointing to in the kidneys?
4. What is the normal length for an adult kidney?

Back 1

Normal Kidneys
1. The kidneys shown in tlus case are normal.
2. The first image is the right kidney and the second
image is the left kidney. The only way to tell the
difference is to compare the echogenicity of the
adjacent liver and spleen. The normal liver is
usually sin1ilar or slightly more echogenic than the
right kidney. The spleen is conSiderably more
echogeluc than the left kidney.
3. The arrows are pointing to the renal pyramids.
4. The normal adult kidney is approximately 11 cm ±
2 cm.
Reference
Thurston W; Wilson SR: The urinary tract. In Rumack
CM, Wilson SR, Charboneau JW (eds): Diagnostic
Ultrasound, 2nd eel. St. Louis, Mosby, 1998, pp 329-
399.
Cross-Reference
Ultrasound: THE REQUISITES, pp 73-77.
Comment
Unlike most of the other solid organs in the abdomen,
the kidneys have a relatively complex sonographic appearance.
The central renal sinus contains a combination
of fat and soft tissue and appears echogenic. The
renal parenchyma, on the other hand, is hypoechoic. In
many patients, including the one shown in tlus case, it
is possible to visualize the renal pyramids as structures
even slightly less echogenic than the renal cortex. Normally,
the renal parenchyma is the least echogenic solid
organ in the upper abdomen, followed by the liver, the
spleen, and the pancreas.
When performing scans of the kidneys, it is important
to compare their echogenicity to that of the
liver and the spleen. This allows for detection of abnormally
echogenic kidneys, as well as abnormalities in
hepatic and splenic echogenicity. Therefore, views including
a portion of the liver and spleen, such as those
shown in tlus case, are important to obtain. Given tlle
size of the liver, it is typical to view the right kidney
using the liver as a window, so comparison of the right
kidney with the liver is generally easy. Since the spleen
is much smaller than the liver, comparison of the spleen
with the left kidney is more difficult. Nevertheless, a
high posterior and lateral approach with the patient
supine will work for almost all patients except those
with unusually small spleens. It is also helpfcJl to scan
both kidneys from a posterior and lateral approach without
using the liver or spleen as windows, since this will
provide a closer approach to the kidneys and in some
cases will allow you to identify abnormalities that might
otherwise be overlooked.

Front 2

Lon g itudinal and tra nsverse views of the g a l l b ladder.
1 . Should the abnormality shown on these images move when the patient rolls?
2 . What causes the echogenicity of the bile in this condition?
3. Is surgery indicated?
4. What less common causes are there for this sonographic appearance?

Back 2

G al l bladder Sludge
1. Sludge should move t o the dependent portion of
the gallbladder when the patient changes position.
2. The echogenicity of sludge is due to crystals,
especially cholesterol and calcium bilirubinate.
3. Sludge will usually resolve without any
complications, so surgery is usually not indicated.
4. Blood and pus can simulate sludge.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1993, pp 116-142.
Cross-Reference
Ultrasound: THE REQUISITES, pp 40-4 1 .
Comment
Gallbladder (GB) sludge consists of viscous bile that
contains cholesterol crystals and calcium bilirubinate
granules. It appears as echogenic material in the lumen
of the GB. Since it is not attached to the GB wall, sludge
should be mobile. However, if the bile is very thick and
viscous, mobility may be very slow. Usually, sludge will
layer into the dependent portion of the GB, and a
straight line will form between the sludge and the rest
of the bile in the GB. In some patients, sludge will
completely fill the lumen of the GB. Sludge is usually
homogeneous but occasionally will contain areas of heterogeneity.
Blood and pus both can simulate sludge but
are much less common. Unlike GB stones, sludge does
not shadow. If even slight shadowing is detected within
sludge, it indicates the presence of associated stones.
The clinical Significance of sludge is not well established.
In most instances, it is asymptomatic and resolves
spontaneously. In some cases, it progresses to
gallstone formation.

Front 3

Two longitu d i n a l views of the lowe r pole of the same kidney.
1. What important finding is seen on the second image but not on the first?
2. Why doesn't the first unage show this important finding?
3 . Does this lesion requu'e further evaluation?
4. What is the major complication of this lesion?

Back 3

Angiomyol i poma
1. Both images show a hyperechoic mass, but the
second image also shows slight posterior
shadowing. These findings are typical of an
angiomyolipoma (AML).
2. The shadowing is not seen on the first unage
because it was taken with a lower frequency
transducer (4 MHz versus 8 MHz).
3. Further evaluation of a lesion such as tIlls is
controversial. However, since renal cell carCUloma
is occasionally sunilarly hyperechoic, it is not
unreasonable to recommend either a noncontrast
CT or MRI to prove that the lesion contains fat, or
follow-up sonography to prove stability.
4 . The major complication of an AML is bleedulg.
Reference
Siegel CL, Middleton WD, Teefey SA, McClennan BL:
Angiomyolipoma and renal cell carCUloma: Ultrasound
differentiation. Radiology 1996; 198:789-793.
Cross-Reference
Ultrasound: THE REQUISITES, pp 93-94.
Comment
AML is a benign renal tumor that contains fat, smooth
muscle, and vessels. These tumors can occur either
sporadically or Ul association with tuberous sclerosis.
Sporadic AMLs typically occur Ul middle-aged women
and are solitary. On the other hand, AMLs associated
with tuberous sclerosis are usually multiple, small, and
bilateral and show no gender predilection.
The great majority of AMLs are asymptomatic. Large
AMLs (>4 cm) may cause bleeding into the subcapsular
or perinephric space. TIlls bleeding may be related Ul
part to the abnormal vessels and nlicroaneurysms that
are present Ul these tumors. Some urologists advocate
removal of these large lesions.
The sonographic appearance of an AML is Llsually
very typical. In approximately 80% of cases, an AML
appears as a homogeneous hyperechoic mass similar in
echogenicity to renal sinus or perulephric fat. A small
percentage of AMLs are less echogelllc than fat but
more echogenic than renal parenchyma.
Although the usual appearance of an AML is very
characteristic, it does overlap with the appearance of
renal cell cancer CRCC). Approximately 10% of all RCC
appears echogenic enough to simulate an AML. This is
even more common rn small RCC. Some features can
help in the differentiation of echogelllc RCC and AML.
If any cystic elements or a hypoechoic halo or calcification
are seen, then the mass is much more likely to be
RCC. On the other hand, if there is attenuation of the
sound so that there is slight posterior acoustic shadowing,
then the mass is much more likely to be an AML
than RCC.

Front 4

Transverse and longitudinal views of the l iver.
1 . What structure is the large arrow pointing to Ul the first image?
2. What structure are the small arrows pOinting to in both images?
3. What embryologic remnant travels in the structures uldicated by the arrows?
4. What liver segments are indicated by the numbers 1 , 2, and 3 in the first image, and what vessels are
indicated by the numbers 4 and 5 in the second image?

Back 4

Normal Anatomy of the Liver
1. The large arrow is pornting to the ligamentum
teres.
2. The small arrow is pou1trng to the fissure for the
ligamentum venosum.
3. The umbilical vern remnant travels in the
ligamentlll11 teres, and the ductus venosus travels Ul
the fissure for the ligamentum venosum.
4. 1 Caudate segment, 2 = Left lateral segment,
3 Left medial segment. 4 = Left hepatic vern,
5 Branch of the left portal vein.
Reference
Withers CE, Wilson SR: The liver. In Rumack CM, Wilson
SR, Charboneau ]W (eds): Diagnostic Ultrasound,
2nd ed. St. Louis, Mosby, 1998, pp 87- 1 54 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 3-5.
Comment
The ductus venosus is the embryologic vessel that provicles
communication between the umbilical vern and
the inferior vena cava. It runs between the umbilical
segment of the left portal vein and the most superior
aspect of the ulterior vena cava. It is .embedded Ul
the liver via a deep fissure that can be seen on both
longitudinal and transverse images of the left lobe of
the liver. This fissure separates the caudate lobe from
the lateral segment of the left lobe. Whenever the fissure
for the ligamentum venosum is seen, the portion
of the liver seen anteriorly must be the lateral segment
of the left lobe. Therefore, in the 10ngitudu1a1 view, the
portal vein branch and hepatic vern branch that are seen
must be branches of the left portal vein and hepatic vern
that supply the lateral segment.
The ligamentum teres is the remnant of the umbilical
veUl. On transverse views such as those shown rn this
case, it appears as a round, echo genic structure that
often produces some posterior shadowulg. It attaches
to the most anterior aspect of the left portal vern. In
the fetus, blood flow from the umbilical vein travels
into the liver, through a short segment of the left portal
vern, and then u1to the ductus venosus. The segment of
the left portal vein that connects the umbilical vein to
the ductus venosus is called the umbilical segment of
the left portal veUl. The ligamentum teres and the umbilical
segment of the left portal vein both separate the
medial and lateral segments of the left lobe.

Front 5

Longitudinal and tra nsverse views of the porta hepati s .
1 . Name the numbered normal structures on the longitudinal view.
2 . Name the numbered normal structures on the transverse view.
3 . Are measurements of the common duct obtained from the inner wall or the outer wall?
4 . What segment of the bile duct is usually the largest?

Back 5

N ormal Anatomy of the Common Bile Duct
1. 1 = Common bile duct, 2 = Right hepatic artery,
3 = Portal vein, 4 = Inferior vena cava, 5 = Right
renal artery, 6 = Crus of the right diaplu'agm, 7
Cystic duct insertion.
2. 1 = Portal vein, 2 = Proper hepatic artery, 3 =
Common hepatic duct.
3. Bile duct diameter is measured from inner wall to
inner wall. TIlis is done to allow for better
correlation with measurements taken during
cholangiography.
4. The bile duct diameter is usually greatest in its mid
segment (Le., between the porta hepatis and the
pancreatic head).
Reference
Middleton WD: The bile ducts. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wil·
kins, 1993, pp 146-172.
Cross-Reference
Ultrasound: THE REQUISITES, pp 55-57.
Comment
The left and right hepatic ducts join each other to form
the common hepatic duct. The common hepatic duct
joins the cystic duct to form the common bile duct.
Although it is visualized in this case, the insertion of
the cystic duct is usually difficult to visualize. Therefore,
it is usually not possible to precisely determine where
the junction of the common hepatic duct and the com·
mon bile duct is located. For this reason, many ultraso·
nologists refer to the common hepatic duct and the
common bile duct together as the "common duct."
In most views of the porta hepatis, it is easy to
identify the portal vein and to identify tubular structures
anterior to the portal vein that represent the hepatic
artery and the common duct. The common hepatic
artery arises from the celiac axis. Following the takeoff
of the gastroduodenal artery, it ascends into the porta
hepatis as the proper hepatic artery. Therefore, the
proper hepatic artery is usually what is visualized in the
porta hepatis.
As shown in this case, the proper hepatic artery is
usually more to the left and the common duct to the
right : This can be easily remembered, since the artery
arises from the aorta (which is to the left of the midline)
and the common duct arises from the liver (which is to
the right of the midline). After the proper hepatic artery
bifurcates into the right and left hepatic arteries, the
right hepatic artery crosses between the portal vein
and the common duct. This produces the classic view
showing the bile duct in long axis, the right hepatic
artery in short axis, and the portal vein in an oblique
axis, which is shown in the first image.

Front 6

Long itudinal view of the right posterior hem ithorax and tra n sverse view
of the right u p per quadrant o btai n ed in two patients.
1 . What is the diagnosis in these two patients?
2. To what is the large arrow pointing?
3. To what are the small arrows pointing?
4. When the abdomen is scanned, is this abnormality easier to detect on the right side or on the left
side?

Back 6

Pleural Effusion
1. Both patients have pleural effusions.
2. The large arrow is pointing to atelectatic lung
floating in the pleural fluid.
3. The small arrows are pointing to aerated lung and
the posterior shadow.
4. Pleural effusions are easier to see on the right side
because the liver provides a better window to the
costoplu'enic angle than does the spleen.
Reference
Brant WE: The thorax. In Rumack CM, Wilson SR, Charboneau
JW (eds): Diagnostic Ultrasound, 2nd ed. St.
Louis, Mosby, 1998, pp 575-598.
Cross-Reference
Thoracic Radiology: THE REQUISITES, P 491.
Comment
Pleural effusions are frequently seen as incidental find·
ings on abdominal scans. Normally, the aerated lung is
closely applied to the diaplu-agm, so that sound cannot
penetrate to the posterior structures of the chest. Pleural
effusions displace aerated lung enough to provide a
window to the posterior surface of the costoplu-enic
sulcus. When the effusion is small, this produces a
triangular-shaped collection. When the effusion is larger,
there is usually associated compressive atelectasis of the
lung, producing a mobile, curvilinear soft-tissue structure
floating within the fluid. Aerated lung, appearing
as hyperechoic tissue with dirty posterior shadowing, is
often seen above the atelectatic lung. Perillepatic ascites
is easily differentiated from pleural effUSions, since ascites
will clisplace the diaphragm from the liver, malting
the diaplu'agm appear as a separate structure. In addition,
the bare area of the liver prohibits ascites from
extending to the posterior medial aspect of the liver.
Pleural effusions typically do extend to the most medial
aspect of the liver, near the vena cava.
As shown on the first itnage, pleural effusions can
also be seen by scannitlg dit'ectlv over the chest wall in
the region of the effusion. This
'
scannitlg is commonly
done when performing ultrasound-guided thoracentesis.
The fluid is seen separatitlg the parietal and visceral
layers of the pleura. In the longituditul plane, the ribs
are seen as shadowing echogenic structures and the
parietal pleura as a smooth, litlear reflection deep to
the ribs. Pleural effusions that appear simple on sonography
may be either transudative or exudative. Complex
effusions that contain septations and/or internal floating
reflectors are usually exudative.

Front 7

Two tra nsverse and two longitudinal views of the scrotu m .
1 . What i s the normal echogenic structure (arrow) shown on the first transverse view and the first
longitudinal view?
2 . What are the normal peritesticular structures labeled 1 and 2 on the second transverse view and the
second longitudinal view?
3. What is the normal relative echogenicity of the testis and of the head of the epididymis?
4. What is the normal relative echogenicity of the testis and of the body of the epididymis?

Back 7

N ormal Scrotal Anatomy
1. The peripheral echogenic structure is the
mediastinum of the testis.
2. 1 = Head of the epididymis, 2 = Body of the
epididymis.
3. The head of the epididymis is normally isoechoic to
the testis.
4. The body of the epididymis is normally hypoechoic
to the testis.
Reference
Feld R, Middleton WD: Recent advances in sonography
of the testis and scrotum. Radial Clin North Am
1992;30:1033-1051.
Cross-Reference
Ultmsound: THE REQUISITES, pp 435-436.
Comment
The testes are paired ovoid organs residing within the
two halves of the scrotum. Six scrotal layers (the skin,
dartos, external spermatic fascia, cremasteric muscle,
internal spermatic fascia, the tunica vaginalis) surround
them and the testicular capsule called the tunica albuginea.
The two scrotal sacs are divided by a midline
median raphe.
Each testis is divided into approximately 300 lobules.
Each lobule contains up to four extremely convoluted
seminiferous tubules. As they converge to exit the testis,
the seminiferous tubules join together to form the
straight tubules. The straight tubules then join to form
a plexus of channels called the rete testis that is located
within an infolding of the tunica albuginea called the
mediastinum. The mediastinum is the hilum of the testis.
The rete testes empty into the head of the epididymis
via 10 to 15 efferent ductules. In the head of the
epididymis, the efferent ductules join together to form
a single convoluted ductus epididymis. The epididymis
is a crescent-shaped structure that rests on the surface
of the testis near the mediastinum. It is divided into
the head superiorly, the tail inferiorly, and the body in
between.
The normal testis has a low- to medium-level echogenicity
and a homogeneous echotexture. It measures
approximately 4 cm in length and 2 cm in width and
thickness. In most testes the mediastinum is seen as an
echogenic structure at the periphery of the testis that
runs from the upper third to the lower third of the
testis. The epididymal head rests on the upper pole of
the testis and has an echogenicity similar to that of the
testis. During real-time scanning, the epididymal head
can usually be followed into the body of the epididymis,
10
which is slightly less echogenic than the testis. The
location of the epididymal body is variable because the
testis itself is somewhat mobile within the scrotal sac.
Most often, the epididymal body is seen along the anterior
and lateral aspect of the testis, as shown on the
second transverse unage. In some patients the epididymal
body is located posterior to the testis, as shown on
the second longitudinal image. A small amount of fluid
is often seen in the scrotal sac, usually around the
epididymal head.

Front 8

Transverse and sag ittal views of the u pper abdomen.
1. Name the normal numbered structures on the transverse scan.
2. Name the normal numbered structures on the sagittal scan.
3. Is the pancreatic body normally round or oval-shaped on sagittal scans?
4. Is the superior mesenteric artery or vein closer to the pancreas?

Back 8

N ormal Peri pan creatic Anatomy
1. 1 = Left lobe liver, 2 = Pancreas, 3
Porto splenic confiuence, 4 = Aorta, 5 = Inferior
vena cava (lYC), 6 = Superior mesenteric artery
(SMA), 7 = Common bile duct (CBD) , 8 =
Gastroduodenal artery.
2. 1 = Left lobe liver, 2 = Pancreas, 3 = Splenic
vein, 4 = Aorta, 5 = Celiac axis, 6 = SMA, 7
Left renal vein, 8 = Gastric antrum.
3. The pancreatic body is oval on sagittal scans.
4. The superior mesenteric vein is immediately
adjacent to the head and uncinate process of the
pancreas. The SMA is separated from the pancreas
by a ring of echo genic fibrofatty tissue.
Reference
Schneck CD, Dabezies ]\ItA, Friedman AC: Embryology,
histology, gross anatomy, and normal imaging anatomy
of the pancreas. In Friedman AC, Dachman AH
(eds): Radiology of the Liver, Bilia1Y Tract, and Pancreas.
St. Louis, Mosby, 1 994, pp 715-742.
Cross-Reference
Ultrasound: THE REQUISITES, pp 122-124.
Comment
The pancreas is one of the more difficult organs to
visualize with ultrasound. Knowledge of the peripancreatic
vessels aids greatly in localizing the gland. The
most useful landmark is the portosplenic venous confluence.
On transverse scans, this appears as a tadpoleshaped
hypoechoic to anechoic structure posterior to
the body of the pancreas. The head of the pancreas
wraps around the r ight lateral aspect of the portal vein
at the level of the portomesenteric confluence, and
the uncinate process extends posterior to the superior
mesenteric vein. All of the peripancreatic veins are unmediately
adjacent to the pancreas without any intervening
fatty tissue. On the other hand , the peripancreatic
arteries are surrounded by echogenic fibrofatty
tissue and do not make dU'ect contact with the pancreas.
The celiac axis typically arises at the superior
aspect of the pancreas. The body of the pancreas can
be seen by scanning just below the OrigUl of the proper
hepatic artery and splenic artery. The SMA arises from
the aorta unmediately posterior to the pancreas and the
portosplenic confluence. A characteristic hyperechoic
ring of fibrofatty tissue surrounds the SMA.
The CBD travels in the most posterior aspect of the
pancreas. In fact, it often appears iInmediately anterior
to the rve. The gastroduodenal artery arises from the
common hepatic artery and descends along the anterior
aspect of the head of the pancreas. These two structures
often appear as two small anechoic dots on transverse
views of the pancreatic head.

Front 9

Long itudina l views of two patients with the same a bnorm a l ity.
1. What is wrong with these kidneys?
2. Under what circumstances is this a medical emergency?
3. How would you grade the abnormality shown here?
4 . In what plane are these images acquired?

Back 9

Hyd ronephrosis
1. The renal collecting system is dilated.
2. If the kidney is infected and obstructed.
3. This is referred to as grade 2 hydronephrosis.
4. Coronal or semicoronal.
Reference
Ellenbogen PH, Scheible Fw, Talner LB, Leopold GR:
Sensitivity of gray scale ultrasound in detecting urinary
tract obstruction. AJR Am J Roentgenol
1978;130:731-733.
Cross-Reference
Ultrasound: THE REQUISITES, pp 77-8 l .
Comment
Sonographic detection of urulary obstruction depends
on identification of a dilated collecting system, which
appears as anechoic spaces within the echogenic central
renal sinus. Under most circumstances, it is easy to
document that the cystic spaces communicate w i t h
each other and with the renal pelvis. This confirms that
the fluid is Ul the collectulg system.
Hydroneplu'osis is graded into different levels of severity.
Grade 0 refers to a normal sonogram. Grade 1
refers to minimal separation of the central echogenic
renal SU1US. Grade 2 refers to obvious distention of
the renal collecting system. Grade 3 refers to marked
distention of the renal collectillg system with associated
cortical thinning.
Whenever hydronephrosis is detected, the next task
is to determine the level and cause of obstruction.
When the hydronephrosis is bilateral, the obstruction is
often at the level of the bladder, and tIllS is usually easy
to document sonographically. Prostatic hypertrophy is
easy to identify Ul men, and pelvic tumors are usually
easy to identify ill women. Primary bladder tumors are
often easily identified ill both genders. Unilateral obstruction
of the ureter at a level above the bladder is
more difficult to sort out with ultrasound. Depending
on the patient, it may be possible to follow the ureter
over its entire course and document the transition
POUlt. However, the mid ureter is often not visible, and
unless the obstruction is caused by a sizable mass, the
source of mid-ureteral obstruction may not be visible
sonographically. In such cases, sonography should be
followed by further imaging tests, such as intravenous
urography, CT, or retrograde pyelography.

Front 10

Tra nsverse views of the l ive r.
1 . What is the echogenic structure indicated by the long arrow?
2 . What is the linear structure indicated by the short arrow?
3. What is the fluid-filled structure indicated by the number I ?
4 . What liver segments are indicated by the numbers 2 , 3 , and 4?

Back 10

Normal Liver and Gallbladder Anatomy
1. The long arrow is pointing at the ligamentum teres.
2. The short arrow is pointing at the interlobar fissure.
3. The number 1 is identifying the gallbladder.
4. Numbers 2, 3, and 4 are in the left lateral, left
medial, and right anterior segments, respectively.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. BaItin10re, Williams & Wilkins,
1 993, pp 116-142.
Cross-Reference
Ultrasound: THE REQUISITES, pp 35-38.
Comment
The normal gallbladder (GB) is located along the inferior
and posterior aspect of the liver. It rests between the
right and left lobes and serves as a valuable landmark
to help separate the right and left lobes. In most fasting
patients, the GB is readily identified simply by moving
the transducer along the right inferior costal margin
while visualizing the lower margin of the liver. In cases
where the GB is difficult to find, it is helpf-ul to use
hepatic landmarks. Start by finding the ligamentum teres
between the medial and lateral segments of the left
lobe. It typically appears as a round, echogenic structure,
often with some posterior shadowing. Then look
to the right for the interlobar fissure. This fissure is a
shallow indentation on the posterior-inferior aspect of
the liver that appears as an echogenic line extending
from the porta hepatis into the liver parenchyma. The
interlobar fissure separates the left lobe (medial segment)
and right lobe (anterior segment). The GB is
located in1mediately adjacent to the interlobar fissure.
In some patients, the interlobar fissure is not visible
sonographically. This most often occurs when the GB is
well distended. Fortunately, the interlobar fissure is usually
easiest to see in those situations when the GB is
contracted and harder to see.
The GB is usually well distended in a patient after an
overnight fast. The upper limit of normal for GB size,
even in a fasting patient, is 4 cm in the transverse
plane. The transverse diameter is a better indicator of
overdistention than the longitudinal diameter. Nevertheless,
most GBs will be less than 8 cm in length. The GB
wall thickness shmud not exceed 3 mm. When the GB
is contracted, the wall may seem thick and the muscle
layer may become apparent as a hypoechoic layer deep
to the mucosa . However, even in the contracted state,
it is unusual for the wall to measure more than 3 mm.

Front 11

Views of the l iver in two patients.
1 . Are these lesions most likely benign or malignant?
2 . What is the differential diagnosis?
3 . What does the peripheral hypo echoic region represent?
4. Is the differential diagnosis the same for a lesion that is hypoechoic centrally and has a hyperechoic
peripheral ring?

Back 11

Hepatic Target Lesions
1. Target lesions are much more likely to be
malignant.
2. The differential diagnosis includes metastases,
hepatocellular cancer, lymphoma, and abscess.
Benign lesions such as focal nodular hyperplasia or
hepatic adenomas are possible but much less likely.
3. The hypo echoic halo is usually viable tumor but
may occasionally be compressed liver parenchyma.
4. Reverse targets are much less likely to be malignant.
References
Kruskal JB, Thomas P, Nasser I, et al: Hepatic colon
cancer metastases in mice: Dynamic in vivo correlation
with hypoechoic rims visible at US. Radiology
2000;215 :852-857.
Wernecke K, Vassallo P, Bick U, et al: The distinction of
benign and malignant liver tumors on sonography :
Value of the hypoechoic halo. AJR Am J Roentgenol
1992; 159: 1005-1 009.
Cross-Reference
Ultrasound: THE REQUISITES, pp 7-9.
Comment
The lesions shown in these figures have an isoechoic or
hyperechoic center and a hypoechoic rim. This appearance
is referred to as a target lesion, and the great
majority of these lesions are malignant. Liver metastases
are most common, but hepatocellular carcinoma and
lymphoma can also have a target appearance and should
be considered in the proper clinical setting. Initial discussions
of target lesions stated that the hypoechoic rim
represented compressed liver parenchyma. This may be
true when the hypoechoic halo is thin. However, more
recent reports show that in most cases, the rim represents
viable tumor. In fact, when performing percutaneous
biopsy of these lesions, the highest yield is from
the hypoechoic rim.
It is very uncommon to see target lesions from benign
etiologies. Hepatic adenomas and focal nodular
hyperplasia rarely appear as target lesions, but they are
much less common than hepatic metastases. Hemangiomas
are extremely common liver tumors, but it is rare
for them to have a hypoechoic rim. It is important to
recognize that reverse target lesions (lesions with an
isoechoic or hypoechoic center and a hyperechoic rim)
are unlikely to be malignant. In fact, this is a relatively
typical appearance for a hemangioma.

Front 12

Longitud inal and transverse views of the shoulder.
1 . Identify the numbered normal structures in the two figures above.
2. The rotator cuff is composed of how many tendons?
3. What structure separates the subscapularis from the supraspinatus?
4. Is the normal rotator cuff compressible?

Back 12

Normal Anatomy of the Shoulder
1. 1 = Rotator cuff (RC), 2 = Cartilage, 3 = Humeral
head, 4 = Anatomic neck, 5 = Greater tuberosity,
6 = Subdeltoid bursa, 7 = Deltoid, 8 = Biceps
tendon.
2. The rotator cuff is composed of four tendons and
muscles, the subscapularis, the supraspinatus, the
infraspinatus, and the teres minor.
3. The intra-articular portion of the biceps tendon
separates the subscapularis and the supraspinatus.
4. The normal rotator cuff is not compressible.
Reference
Middleton WD, Teefey SA, Yamaguchi K: Sonography of
the shoulder Semin Musculoskeletal Radiol 1 998;
2 : 2 1 1 -2 2 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 4 5 5 -457.
Comment
The RC is a band of conjoined tendons that covers
the humeral head. The anterior tendon (subscapularis)
crosses the glenohumeral joint and attaches to the lesser
tuberosity. The superior tendon (supraspinatus) attaches
to the greater tuberosity just posterior to the biceps
tendon groove. The intra-articular portion of the long
head of the biceps tendon separates these two tendons.
Anatomic studies have shown that the supraspinatus
tendon measures approximately 1 . 5 cm in width. Behind
and inferior to the supraspinatus tendon is the
infraspinatus tendon, which also inserts on the greater
tuberosity. A minor tendon located just inferior to the
infraspinatus is the teres minor.
Sonograms of the shoulder display multiple structures
in a series of layers. The deepest structure is the
humeral head, which appears as a strong, curvilinear
reflection. On longitudinal views, the concave anatomic
neck separates the humeral head and the greater tuberosity.
Immediately on top of the humeral head is a thin
layer of anechoic or hypoechoic articular cartilage. The
next layer is the RC, which appears as a thick (4 to 6
mm) band of tissue. In most patients the RC appears
hyperechoic compared to the overlying deltoid muscle.
[n elderly patients, the RC and the deltoid may appear
more similar in echogenicity. Superficial to the RC is a
thin, hypoechoic layer that represents the subdeltoid
bursa. Superficial to this is a thin, hyperechoic layer that
represents peribursal fat. The deltoid muscle is the final
layer. Like other muscles, it is hypoechoic.
The outer surface of the normal RC is convex. Conversion
to a concave contour is an important sign of a
full-thickness RC tear. In addition, the normal RC is not

Front 13

Longitudinal i mages of the g a l l bladder i n two patients.
1 . Do these patients have anything in common?
2. What is the differential diagnosis?
3. What do you think is the cause of the abnormality in these two patients?
4. Are any measurements useful in detecting this abnormality?

Back 13

G a l l b ladder Wal l Th icken ing
1 . Both patients have thick gallbladder (GB) walls. The
first image also shows ascites and a nodular liver
consistent with cirrhosis. The second image also
shows a completely contracted GB lumen.
2. The causes of a thick GB wall include heart failure,
hypoproteinemia, edema-forming states, hepatitis,
Cirrhosis, portal hypertension, lymphatic
obstruction, GB cancer, adenomyomatosis, and
cholecystitis.
3 . The nodularity of the liver surface in the first image
is consistent with cirrhosis, and this is the cause of
the GB wall thickening. The lumen of the GB is
completely contracted in the second image, and
tI1is finding should raise the possibility of hepatitis.
4. The upper limit of normal for GB wall thickness is
3 mm.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & WilkillS,
1 993, pp 1 16 - 1 42 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 49- 50.
Comment
A large number of processes can cause tI1ickening of
the GB wall. Most of the etiologies are not related to
intrinsic GB disease. These non-biliary causes produce
thickening of the GB wall as a result of edema. I n
general, the most pronounced GB wall thickening i s
usually due t o one o f these non-biliary causes. Acute
hepatitis in particular can cause extensive GB wall thickening.
Hepatitis may also result in contraction of the GB
lumen to the point that the lumen is completely collapsed.
As shown in the second image, a collapsed
lumen is seen as a linear reflection from the apposed
walls of the lumen.
In most cases, marked GB thickening is manifested
by irregular or striated intramural sonolucencies, as is
seen in this case. When this pattern is noted, it usually
means that the thickening is not related to cholecystitis.
However, if tI1is pattern is identified in a patient with
well-established clinical and sonographic evidence of
cholecystitis, then it usually indicates more advanced
disease.

Front 14

Tra nsverse view of the l iver.
1 . What are the vascular structures indicated by the numbers I , 2, and 3?
2. What segments of the liver, indicated by the numbers 4, 5 , 6, and 7, do these vessels separate?
3. How can you distinguish the hepatic veins and portal veins on a static grey-scale view of the liver?
4 . To what vein does the caudate lobe drain?

Back 14

Normal Hepatic Venous Anatomy
1 . The three vessels are the hepatic veins. 1 = Right,
2 = Middle, 3 = Left. This view is usually obtained
from an epigastric approach with the transducer
angled superiorly.
2 . The right hepatic vein separates the anterior (5)
and posterior (4) segments of the right lobe. The
middle hepatic vein separates the anterior segment
of the right and the medial segment (6) of the left
lobe. The left hepatic vein separates the left lateral
(7) and the left medial segments.
3. Unlike the portal veins, the hepatic veins are not
surrounded by fibrofatty tissues and therefore have
much less echogenic walls. In fact, under most
circumstances, the wall of the hepatic vein is not
visible sonographically. The exception is when the
hepatic vein is viewed with the walls perpendicular
to the direction of the sound. In this situation, the
wall produces a specular reflection and appears as a
thin, echogenic line. This is well demonstrated in
the right hepatic vein on the first unage.
4. The caudate lobe drauls into the vena cava via small
veins that are separate from the three main hepatic
veins. This is the reason the caudate veU1S function
as collaterals in patients with Budd-Chiari
syndrome.
Reference
Schneck CD: Embryology, histology, gross anatomy and
normal unaging anatomy of the liver. In Friedman
AC, Daclunan AH (eds): Radiology of the Liver, Biliat)1
Tract, and Pancreas. St. Louis, Mosby, 1 994,
pp 1 -25.
Cross-Reference
Ultrasound: THE REQUISITES, pp 3 - 5 .
Comment
Three major veU1S drain hepatic blood flow UltO the
vena cava. The main hepatic veins travel between the
segments of the liver and therefore are used as landmarks
for identifying the segments. The middle and left
hepatic veins usually join together before emptying into
the inferior vena cava. In most patients, the right hepatic
veul is best itnaged from an ultercostal approach
near the mid axillary line. Tlus not only allows for visualization
on grey-scale but also provides a good angle for
Doppler imaging. The left hepatic vein is best itnaged
from a midlule subxiphoid approach. The middle hepatic
vein is best seen from an approach somewhere
between the right and left veUl.
In addition to the three maUl hepatic veins, a variable
number of smaller dorsal hepatic veins may draul directly
into the vena cava from the posterior right lobe
and the caudate lobe. These dorsal veins often act as
collaterals when the three main veins are obstructed

Front 15

Longitudinal views of the porta hepatis i n two patients.
1 . Where is the common duct in these patients?
2 . In what percentage of patients is the duct located as shown here?
3. Which is straighter, the bile duct or the hepatic artery?
4. Which varies more in caliber, the bile duct or the hepatic artery?

Back 15

Va riant Relationship of Right Hepatic
Artery and Bile Duct
1 . In both cases the bile duct is located between the
portal vein and the right hepatic artery. Normally
the right hepatic artery is located between the
portal vein and the bile duct.
2. This variant occurs in up to 20% of patients.
3. The bile duct is straighter than the artery.
4. The bile duct is more variable in diameter than the
artery.
Reference
Middleton WD: The bile ducts. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltitnore, Williams & Wilkins,
1 993, pp 1 46- 1 72.
Cross Reference
Ultrasound: THE REQUISITES, pp 5 5 -56.
Comment
Anatonuc variations around the porta hepatis are relatively
common. The variant shown in this case, where
the right hepatic a.rtery crosses anterior to the duct, is
reported to occur Ul up to 20% of individuals . However,
it is not documented that commonly on sonography.
SU1Ce the hepatic artery may cross in front of the bile
duct, or the bile duct may pass in front of the hepatic
artery, identification of the bile duct can sometitnes be
COnfUSUlg. One clue that is helpful is that the bile duct
is usually straighter than the hepatic artery. Therefore,
it is easier to get a view of the bile duct that shows it
over several centitneters, whereas the hepatic artery is
too tortuous to see over a significant length. In addition,
the hepatic artery maintaulS a fairly constant diameter,
while the bile duct varies in diameter from proximal to
distal. In many patients, the hepatic artery will indent
the bile duct, but the bile duct never indents the al"tery.
In addition to the right hepatic artery, occasionally
the cystic artery (the artery that supplies the gallbladder)
can be seen near the common bile duct. This artery
usually arises from the right hepatic artery to the right
of the common duct. When it arises to the left of the
common duct, it must cross the common duct on its
way to the gallbladder. In some patients it passes Ul
front and in others it passes bel1ind the common duct.
Therefore, it is possible to see two arteries behi1ld the
duct, an artery in front of and behind the duct, and two
arteries in front of the duct.

Front 16

1 . Name the normal numbered structures on the transverse scan of the right side of the neck.
2. Name the normal numbered structures on the longitudinal scan of the neck.
3. How can the carotid artery be distinguished from the jugular vein on grey-scale scans of the neck?
4. Can the normal parathyroid glands be seen on ultrasonography?

Back 16

Normal Anatomy of the Thyroid
1 . 1 = Right thyroid lobe, 2 = Thyroid isthmus, 3
Carotid, 4 = Jugular, 5 = Trachea shadow, 6 =
Strap muscles, 7 = Sternocleidomastoid muscle,
8 = Longus coli muscle.
2. 1 = Thyroid, 2 = Strap muscles, 3 = Sternocleidomastoid
muscle, 4 = Cartilage rings of trachea.
3. The carotid artery is circular, the jugular vein is
oval. The carotid is more medial and deep, the
jugular is more lateral and superficial. The carotid is
noncompressible, the jugular is easily compressible.
The diameter of the carotid is constant, the
diameter of the jugular varies.
4. The normal parathyroids are too small to be seen
on sonography.
Reference
Solbiati L, Livraghi T, Ballarati E, et al: The thyroid. In
Solbiati L, Rizzatto G (eds): Ultrasound of Superficial
Structures. Edinburgh, Churchill Livingstone, 1 995 ,
pp 49-86.
Cross-Reference
Ultrasound: THE REQUISITES, pp 448-449.
Comment
The normal thyroid gland consists of a left and a right
lobe connected by a thin isthmus. It is located in the
inferior aspect of the neck on both sides of the trachea.
A minority of patients have a thin pyramidal lobe that
extends superiorly from the isthmus and can be seen in
childhood. In adults, the normal thyroid is 4 to 6 cm
long and 13 to 18 mm in anteroposterior diameter. It
has a homogeneous medium-level echogenicity. Normally,
the thyroid is more echo genic than the overlying
strap muscles and the sternocleidomastoid muscles.
The parathyroid glands typically measure 4 X 3 X 1
mm in size, with the long axis oriented in a craniocaudal
direction. The two superior glands are usually located
behind the mid aspect of the thyroid, and the two
inferior glands are located behind or just inferior to the
lower pole of the thyroid. Approximately 20% of inferior
parathyroid glands are located within 4 cm of the lower
pole of the thyroid. A fifth gland, usually associated
within the thymus, is present in approximately 13% of
patients.

Front 17

Transverse views of the prostate from a transrectal approac h . The seco nd
image was obtained s l ightly superior to the first.
1 . What zone of the prostate is indicated by the numbers 1 and 2 ?
2 . What structures are shown i n the second unage?
3. What zone is the largest, and how does this vary with age?
4 . What is the normal value for prostate-specific antigen (PSA)?

Back 17

N ormal Prostate
1. Number 1 indicates the peripheral zone. Number 2
indicates the central gland, which includes the
central zone and the transitional zone.
2. The second image is taken slightly superior to the
first and shows the paired seminal vesicles.
3. In yOlmg men the peripheral zone is the largest.
Because of the effects of benign prostatic
hypertrophy (BPH), the central gland is the largest
in older men.
4. The normal PSA is less than 4 ng/ml.
Reference
Kaye Kw, Richter 1: Ultrasonographic anatomy of the
normal prostate gland: Reconstruction by computer
graphics. Urology 1990;35:12- 1 7.
Cross-Reference
Ultrasound: THE REQUISITES, pp 458-460.
Comment
The prostate is divided into several zones. The peripheral
zone is the largest in normal prostates. It is located
posteriorly and laterally and extends inferiorly to the
prostate apex. The central zone accounts for approximately
25% of normal prostate volume, while the transitional
zone accounts for 5%. The central zone is located
in the middle of the base (superior aspect) of the prostate.
There is also a nonglandular area anteriorly called
the fibromuscular stroma. On sonography, the transitional
zone and the central zone c annot be distinguished,
so they are referred to jointly as the central
gland. The surgical capsule separates the peripheral
zone from the central gland. The normal prostate in a
young man weighs approximately 20 g . A gland
weighing more than 40 g is considered enlarged in
older men. Prostate volume is calculated based on the
equation for an elliptical-shaped structure. A simplified
equation is length times width times height divided
by 2.
Superior to the base of the prostate are the paired
seminal vesicles. They appear as oval shaped and taper
toward the midline. They are normally less echogenic
than the prostate gland.

Front 18

Transverse views of the prostate from a transrectal approac h . The seco nd
image was obtained s l ightly superior to the first.
1 . What zone of the prostate is indicated by the numbers 1 and 2 ?
2 . What structures are shown i n the second unage?
3. What zone is the largest, and how does this vary with age?
4 . What is the normal value for prostate-specific antigen (PSA)?

Back 18

N ormal Prostate
1. Number 1 indicates the peripheral zone. Number 2
indicates the central gland, which includes the
central zone and the transitional zone.
2. The second image is taken slightly superior to the
first and shows the paired seminal vesicles.
3. In yOlmg men the peripheral zone is the largest.
Because of the effects of benign prostatic
hypertrophy (BPH), the central gland is the largest
in older men.
4. The normal PSA is less than 4 ng/ml.
Reference
Kaye Kw, Richter 1: Ultrasonographic anatomy of the
normal prostate gland: Reconstruction by computer
graphics. Urology 1990;35:12- 1 7.
Cross-Reference
Ultrasound: THE REQUISITES, pp 458-460.
Comment
The prostate is divided into several zones. The peripheral
zone is the largest in normal prostates. It is located
posteriorly and laterally and extends inferiorly to the
prostate apex. The central zone accounts for approximately
25% of normal prostate volume, while the transitional
zone accounts for 5%. The central zone is located
in the middle of the base (superior aspect) of the prostate.
There is also a nonglandular area anteriorly called
the fibromuscular stroma. On sonography, the transitional
zone and the central zone c annot be distinguished,
so they are referred to jointly as the central
gland. The surgical capsule separates the peripheral
zone from the central gland. The normal prostate in a
young man weighs approximately 20 g . A gland
weighing more than 40 g is considered enlarged in
older men. Prostate volume is calculated based on the
equation for an elliptical-shaped structure. A simplified
equation is length times width times height divided
by 2.
Superior to the base of the prostate are the paired
seminal vesicles. They appear as oval shaped and taper
toward the midline. They are normally less echogenic
than the prostate gland.

Front 19

Transverse g rey-scale and power Doppler view of the scrotu m i n a
patient with testicu lar pai n .
1 . Which testis is abnormal, and what i s the likely diagnosis?
2. With what condition is this testicular abnormality most often associated?
3. Which is most sensitive for this diagnosis, grey-scale or color Doppler?
4. Is this typically diffuse or focal?

Back 19

Orchitis
1 . Blood flow to the right testis is dramatically
increased. This degree of hyperemia is usually due
to orchitis. Normal flow is present in the left testis.
2. Orchitis is usually associated with epididymitis.
3. Color Doppler shows increased blood flow to the
testis before any grey-scale changes are apparent.
4. Orchitis usually affects the entire testis in a diffuse
manner.
Reference
Horstman WG, Middleton WD, Melson GL: Scrotal inflammatory
disease: Color Doppler ultrasonographic
findings. Radiology 1 99 1 ; 179:55 -59.
Cross-Reference
Ultrasound: THE REQUISITES, pp 445-447.
Comment
Orchitis typically occurs as a secondary event in patients
with primary epididyntitis. However, it can also be isolated,
such as with mumps orchitis or other viral infections.
Regardless of its cause, orchitis is manifest clinically
as an enlarged and painful testis.
On sonography, orchitis appears as a hypoechoic,
enlarged testis. On color Doppler, an inflammatory hyperemia
will appear as increased blood flow to the
affected side. Generally, the changes in blood flow precede
the changes in testicular morphology. Therefore,
color Doppler is more sensitive to the diagnosis than is
grey-scale sonography.
In most cases, the entire testis is involved. When
focal orchitis occurs, it appears as a focal area of decreased
echogenicity and increased vascularity. This sonographic
appearance can overlap with the appearance
of testicular tumors. The easiest way to distinguish a
tumor from focal orchitis is on clinical grounds. Tumors
will usually be readily palpable and nontender, while
focal orchitis is nonpalpable and tender. On sonography,
it is helpful to look at the epididymis. Focal orchitis will
usually be associated with epididymitis, and an enlarged
hyperemic epididymis will be apparent. Testicular tumors
usually do not involve the epididymis. It is also
useful to look in the retroperitoneum, since detectable
adenopathy makes a tumor much more likely than a
benign testicular process

Front 20

Long itud i n a l g rey-scale view of the b l adder and s i m i l a r view with pu lsed
Doppler a n a lysis.
1 . Describe the abnormality.
2. What is the likely diagnosis?
3. Is this abnormality easier to detect on the anterior or posterior wall?
4. What is the most common location of this type of lesion?

Back 20

Tra nsitional Cel l Carcinoma of the Bladder
1. A soft-tissue mass in the base of the bladder with
internal arterial flow.
2 . The most likely diagnosis is transitional cell
carcinoma (TCC).
3. Tumors on the posterior wall are easier to detect
sonographically. Near-field reverberation artifact can
obscure anterior wall masses.
4. TCC of the bladder typically occurs on the lateral
and posterior wall and near the trigone .
Reference
Karcnik T], Simmons MZ, Abujudea HA: Ultrasound imaging
of the adult urinary bladder Ultrasound Q
1 999; 1 5 : 1 3 5 - 1 47
Cross-Reference
Genitourinary Radiology: THE REQUISITES, pp 1 97 -
204.
Comment
Bladder cancer is the 1 1 th most common cancer in the
world. It occurs in men three times more often than in
women. At least 90% of bladder cancers are transitional
cell cancers (TCC). Less than 5% are squamous cell, and
an even lower percentage are adenocarcinomas, small
cell carcinomas, and sarcomas. Smoking predisposes to
TCC and contributes to approximately half of the cases
seen in men. Certain occupational exposures also seem
to predispose to bladder cancer, including the dye, rubber,
and aluminum industries. Excessive exposure to
diesel exhaust and excessive consumption of phenacetin
and acetaminophen are also associated with TCC of
the bladder.
The majority of patients with bladder cancer present
with hematuria. Less commonly, they will have voiding
symptoms such as urgency, dysuria , and frequency.
Flank pain may develop in the setting of ureteral obstruction.
Rarely, patients present with symptoms related
to metastatic disease to the liver, lung, or bones.
Sonography is very good at identifying bladder cancers,
with a sensitivity and specificity of approximately
90%. However, most of these patients have cystoscopy
done as the primary means of finding and quantitating
bladder cancer. Nevertheless, it is very in1portant to
look carefully at the bladder in patients with hematuria,
since ultrasound may be the first study that documents
a tumor. Sonography may also be useful in patients with
bladder diverticulae, in whom it may be difficult to pass
the cystoscope past the neck of the diverticulum.
In patients with hematuria, bladder cancer must be
distinguished from solid clots in the bladder. This is
usually easy, since clots move with changes in patient
24
position. Color Doppler is also valuable, since tumors
often have detectable internal vascularity and clots do
not. In men, an enlarged prostate may produce a mass
that indents the base of the bladder and simulates a
primary bladder mass. This situation should be suspected
whenever the mass is located in the midline
adjacent to the prostate. Occasionally, perivesicular tumors
or perivesicular inflammatory processes involve
the bladder wall and simulate a bladder tumor. Therefore,
careful correlation with clinical history and careful
analysis of perivesicular structures is important.

Front 21

Longitudinal view of the spleen a n d transverse view of the epigastri u m
with p u l sed Doppler wavefo rm of t h e splenic vei n .
1 . What is the upper limit o f normal for spleen length?
2 . Is the flow in this patient's splenic vein normal?
3. What is the likely cause of this patient's splenic abnormality?
4. Does the spleen normally extend below the left kidney?

Back 21

Splenomegaly
1 . Upper limit of normal for splenic length is 1 3 cm.
Upper limit of normal for splenic thickness is 6 cm.
2 . Flow in the splenic vein is reversed.
3. Reversal of splenic vein flow and splenomegaly are
both due to portal hypertension.
4. The spleen normally does not extend below the left
kidney.
Reference
Permutter GS: Ultrasound measurements of the spleen.
In Goldberg BB, Kurtz AS (eds): A tlas of Ultrasound
Measut·ements. Chicago, Year Book, 1 990, pp 1 26-
1 38.
Cross-Reference
Ultrasound: THE REQUISITES, P 1 46.
Comment
Detection of splenomegaly is usually accomplished via
physical examination of the abdomen. However, i n
some patients, physical examination may b e limited by
factors such as obeSity, pain, and marked ascites. It can
also be difficult to distinguish an enlarged spleen from
other left upper quadrant masses. In these patients,
sonography can be very valuable. Not only can ultrasound
evaluate the size of the spleen, but in some
patients it can also determine the cause of an enlarged
spleen and exclude other processes.
Because the spleen is a curved, disk-shaped organ, it
is somewhat difficult to measure in standard planes.
One measurement that is relatively easy to obtain and
to reproduce is the maximum splenic length. For
spleens that are not long but are thick, the short-axis
thickness of the spleen is also a valuable measurement.
The short axis needs to be measured perpendicular to
the long axis of the spleen.

Front 22

Tra nsverse and longitu dinal views of the neck between the thyroi d
carti l age and t h e hyoid bone.
1 . Is it common to see internal echoes in these lesions?
2. Is this a common location for this abnormality?
3. Is this lesion usually unilocular or multilocular?
4. Is tillS lesion likely to be cured with percutaneous aspiration?

Back 22

Thyroglossal Duct Cyst
1 . Although thyroglossal duct cysts are filled with
fluid, the fluid is usually complex-appearing on
sonography, and internal echoes are common.
2. This is the classic location, between the thyroid
cartilage and the hyoid bone.
3. Thyroglossal duct cysts are usually unilocular.
4. Aspiration will not cure a thyroglossal duct cyst.
The cyst wall has to be completely resected, or else
it will recur.
References
Koeller KK, Alamo L, Adair CF, Smirniotopoulos JG:
From the archives of the AFIP: Congenital cystic
masses of the neck: Radiologic-pathologic correlation.
Radiographies 1 999; 1 9: 1 2 1 - 1 46.
Wadsworth DT, Siegel MJ: Thyroglossal duct cysts: Variability
of sonographic findings. AJR A m ] Roentgenol
1 994; 1 63 : 1 475- 1 477.
Cross-Reference
Neuroradiology: THE REQUISITES, P 438.
Comment
Thyroglossal duct cysts are the most common of the
congenital cysts of the neck. They arise along the tract
of the thyroglossal duct. This tract extends from the
foramen cecum at the base of the tongue to the hyoid
bone and finally to the thyroid isthmus or to a pyramidal
lobe. Normally this tract involutes by the eighth week
of fetal development. However, remnants of thyroid
elements remain in approximately 5% of cases. These
remnants can give rise to cysts, fistulae, or solid thyroid
nodules. Histologically, the cyst wall is composed of
squamous cell mucosa, although inflammatory changes
may obscure tllis fact. Despite the pathogenesis, thyroid
tissue is usually not detected on pathologic analysis
of thyroglossal duct cysts. Thyroid cancer is even less
common in these cysts (approximately 1 %) . When it
occurs, it is usually papillary cancer.
Thyroglossal duct cysts typically mal1ifest prior to age
10, although there is a second peak in the young adult
years. They may be painful owing to hemorrhage or
infection. However, many of these cysts are discovered
as painless masses or as incidental findings on imaging
studies done for other reasons. They are located in the
midline, usually at the level of the hyoid bone ( 1 5%) or
just below the level of the hyoid bone (65%). Only 20%
are suprahyoid. Cysts that arise significantly below the
hyoid bone tend to be farther from the midline.
Unlike cysts elsewhere, thyroglossal duct cysts are
usually not anechoic. Low-level internal echoes, as seen
in the case shown here, may be due to hemorrhage,
infection, crystals, or proteinaceous material. Their usu-
26
ally intimate relationship to the hyoid bone is best seen
on longitudinal scans. Although they are usually in the
nliclline, slight pressure applied with the transducer can
sometimes push them to one side or the other.

Front 23

Pulsed Doppler waveforms from two arteries.
1 . Would you characterize these waveforms as high or low resistance?
2. What arteries might display waveforms such as the ones shown in tillS case?
3. What causes the flow below base line on the waveform on the left?
4. What is the resistive index of these waveforms?

Back 23

H igh Resistance Waveforms
1. Both of these waveforms are high-resistance-type
waveforms.
2. High-resistance waveforms can arise from arteries
that supply nonparenchymal structures, such as the
extremities and the bowel. The first waveform
came from the superficial femoral artery, and the
second came from the radial artery.
3. The short phase of early diastolic flow reversal is
caused by elastic recoil of the artery.
4. The resistive index (RI) is calculated as the
difference of peak systole and end diastole divided
by peak systole. The RI equals 1 .0 whenever the
end diastolic flow is zero, as in the first unage. In
the second image the RI equals (40 - 5)/40 =
0.88.
Reference
Nelson TR, Pretorius DH: The Doppler signal: Where
does it come from and what does it mean? AJR Am
J Roentgenol 1 988; 1 5 1 :439-447.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-465.
Comment
The waveforms shown in tllis case have very narrow
and sharply pointed systolic peaks, rapid systolic deceleration
into diastole, and little, if any, late diastolic flow.
There is a short phase of early diastolic flow reversal
seen on the first waveform. These are characteristics of
a lligh-resistance waveform and typically come from
vessels that supply nonparenchymal structures, such as
the extremities. The first waveform is referred to as a
triphaSiC pattern, since there is a phase above the base
line, followed by a second phase below the base line,
followed by a tllird phase above the base line. This is a
classic appearance for an extremity artery. During systole,
the vessel expands as the pressure increases. In
early diastole, the elastic recoil properties of the vessel
result in contraction of the lumen diameter. Resistance
to forward flow is high enough that the majority of the
blood filling the lumen is pushed backward during the
period of elastic recoil, and this results in transient flow
reversal. When the elastic recoil ceases, there is a short
final phase of forward flow.

Front 24

Tra nsverse view of the dorsal surface of the wrist and longitudinal view
of the vo lar surface of the wrist in two patients with the same
abnormal ity_
1 . What is the most common cause of cystic lesions in the wrist?
2. Where do these lesions most often occur?
3. What are these lesions composed of?
4. Are they usually firm or soft?

Back 24

Gangl ion Cyst of the Wrist
1 . Ganglion cysts are the most common cause of cysts
in the wrist and hand.
2. The most common location is the dorsal wrist,
superficial to the scapholunate joint. On the first
image, the surface of the scaphoid and the lunate
are seen as strong linear reflections deep to the
cyst. The space between the two bones is the
scapholunate jOint.
3. Ganglion cysts are usually composed of very thick,
gelatinous liquid.
4. Ganglion cysts are typically very firm and
noncompressible on sonography.
Reference
Middleton WD, Teefey SA, Boyer MI: Hand and wrist
sonography. Ultrasound Q 200 1 ; 1 7: 2 1 -36.
Cross-Reference
Musculoskeletal Imaging: THE REQUISITES, pp 24 1 -
243 .
COlnment
Ganglion cysts are the most common cause of palpable
masses in the hand and wrist. They are most common
in yOlmg women, although they can occur at any age
and in both sexes. They manifest with either localized
pain or a palpable mass.
There are four typical locations. Sixty percent to
70% occur over the dorsal wrist. Dorsal ganglia usually
originate from the scapholunate jOint. They may dissect
proximally or distally. Twenty percent arise on the volar
side of the wrist. Volar ganglia frequently extend around
the flexor carpi radialis tendon or, as shown on the
second image, the radial artery. They typically arise from
one of the radiocarpal joints. The third most common
location is along one of the flexor tendon sheaths. These
cysts account for 1 0% of ganglia. Finally, ganglia can
arise from the interphalangeal joints, usually due to
underlying degenerative arthritis. These cysts have also
been called mucous cysts.
The appearance of ganglia on ultrasound is predictable.
Like other fluid-containing structures, ganglia are
typically anechoic with well-defined wall s . Through
transmission is usually detectable unless the cyst i s
small. Due t o slice thickness artifact, small ganglia may
also have low-level internal echoes. In some cases, a
neck may be seen leading toward the joint of origin.
With large ganglia, there are often folds or septations,
particularly near the neck of the cyst.
Detection of a wrist ganglion is limited by the size
and depth of the cyst. Small and deep ganglia are the
most difficult to detect. Ruptured ganglion cysts may
appear as predominantly solid masses and can also lead
28
to a confusing appearance. Nevertheless, ultrasound remains
an excellent means of evaluating patients with a
suspected ganglion cyst. Accuracy in skilled hands is
sinillar to that of MRI.

Front 25

Tra nsverse g rey sca le and color Doppler views of the right lower
quadra nt.
1 . What is the sensitivity of ultrasound in making this diagnosis?
2. Is this diagnosis easier to make with ultrasound in children or in adults?
3. What are the sonographic criteria for this condition?
, .
4. How do CT and ultrasound compare in evaluating patients suspected of having this condition?

Back 25

Acute Append icitis
1 . The sensitivity of ultrasound for the diagnosis of
appendicitis is 75% to 90%. Positive predictive value
ranges from 9 1 % to 94%, and negative predictive
value ranges from 89% to 97%.
2. Children are usually easier to diagnose than adults
because they typically have less abdominal wall fat.
3 . The criteria for appendicitis are identification of a
blind ending, noncompressible bowel loop that
arises from the cecum and measures 6 mm or more
in diameter. Identification of an appendicolith and
inflamed periappendiceal fat are helpful secondary
signs. Color Doppler demonstration of mural
hypervascularity is also useful.
4. The success of CT and ultrasound in diagnosing
appendicitis depends on institutional preference
and local expertise. In general, radiologists probably
do better with CT than with ultrasound. However,
ultrasound is complementary to CT and is probably
superior in thin patients.
Reference
Birnbaum BA, Wilson SR: Appendicitis at the millennium.
Radiology 2000; 2 1 5 : 337-348.
Cross-Reference
Ultrasound: THE REQUISITES, pp 457-458.
COlnment
In the Western world, acute abdominal pain requiring
surgery is more commonly due to appendicitis than to
any other condition. The peak incidence of appendicitis
is in the second decade of life. The most common
etiology is obstruction from a fecalith. This obstruction
results in increased luminal pressure and eventually in
ischemia. Compromised mucosa subsequently becomes
infected with luminal bacteria. Ongoing infection, ischemia,
and infarction may lead to perforation.
Classic presentation is of vague lower abdominal
pain, nausea, and VOmiting, followed by more discrete
right lower quadrant pain. Patients are usually afebrile
or have a low-grade fever. Accuracy for clinical diagnosis
of appendicitis is approximately 80%. Accuracy is lower
in women of clilldbearing age owing to the clinical
overlap of acute gynecologic disease and acute appendicitis.

Front 26

Two views of the l iver.
1 . Why is the deep aspect of the liver so hypoechoic on the first image?
2. What is the difference between gain and power?
3. Should unage brightness be controlled first with gain or with power?
4. Are gain and power preprocessing or postprocessing controls?

Back 26

Dista nce G a i n Compensation Curve
1 . The distance gain compensation curve is
inappropriately adjusted on the first image.
Increased gain settings were applied to the far field
on the second image, and the liver appears normal
throughout.
2. Power refers to the strength of the sound pulse that
is transmitted by the transducer. Gain refers to the
amount of electronic amplification of the signal that
returns to the transducer.
3. Increasing the power and the gain both result in
brighter images; however, increased power causes
greater patient exposure and can cause artifacts.
Therefore, it is best to increase power only when
an optimal image cannot be obtained first with
adjustment of gain.
4. Preprocessing refers to controls that must be
adjusted in real-time while the patient is being
scanned. Postprocessing refers to controls that can
be adjusted on a frozen image. Gain and power are
both preprocessing controls.
Reference
Zwiebel W]: Image optimization, ultrasound artifacts,
and safety considerations. In Zwiebel W], Sohaey R
(eds): Introduction to Ultrasound. Philadelphia, WE
Saunders, 1 998, pp 1 8-30.
Comment
As sound travels through tissue, it undergoes a number
of interactions. The interactions that allow an unage to
be created are reflection and scattering. In addition,
sound is absorbed by the tissues. These interactions
cause attenuation of the sound pulse as it p *****
through tissue. Since the transmitted pulse and the reflected
pulse both become weaker as they travel
through the tissues, identical reflectors located in the
near field and in the far field produce echoes of different
strengths. To compensate for this, pulses that have traveled
farther are electronically amplified after they return
to the transducer. Tllis process is called distance compensation,
and it is displayed on the inlage as a curve,
called the distance gain compensation (DGC) curve. On
the images shown, the DGC curve appears as a line on
the right side of the image that extends from the near
field to the far field. On the second image, the curve
slopes progressively to the right as it goes from the
near to the far field. This indicates steady progressive
amplification of the echoes returning from the far field.
In the first image, the DGC curve tapers back to the left
in the far field, indicating decreased amplification of the
far field echoes.
30
For homogeneous structures like the liver that attenuate
sound uniformly, the DGC curve should have a fairly
constant up-slope. When fluid-filled structures such as
the bladder are scalU1ed, there is negligible attenuation,
so the DGC curve does not need to provide compensation
until the solid structures deep to the bladder are
encountered.

Front 27

Transverse g rey-scale and color Doppler view of the aorta.
1 . Should surgery be considered in this patient?
2. What itnportant information should be obtauled when scanning a patient such as this one?
3. What is the Significance of the hypoechoic crescent within the mural thrombus?
4. Is color Doppler necessary?

Back 27

Abdominal Aortic Aneurysm
1 . Surgery should be considered when an aneurysm
reaches 5 cm Ul diameter, SU1Ce the ctunulative risk
of rupture over the next 8 years is 2 5%.
2 . It is important to measure the diameter of the
aneurysm and to determine where it starts and
stops with respect to the renal arteries and the
aortic bifurcation.
3. The crescent mdicates liquefied clot. It does not
indicate dissection, rupture, or impendmg rupture.
4. Color Doppler is rarely needed Ul the evaluation of
an aortic aneurysm.
Reference
Nevitt MP, Ballard D}, Hallett JW }r: Prognosis of abdominal
aortic aneurysms: A population based study. N
Engl] Med 1 989;32 1 : 1009- 1 0 1 4 .
Cross-Reference
Gastrointestinal Radiology: THE REQUISITES, P 1 0 2 .
Comment
Abdominal aortic aneurysms are a common abnormality,
especially Ul elderly men, with 95% occurring below
the level of the renal arteries. They are strongly associated
with atherosclerosis. An aneurysm is present when
there is a focal dilatation of the aorta that measures 3
cm or more in diameter. Different groups use different
approaches to the measurement of aortic aneurysms.
The most important issue is to use an approach that is
reproducible, so that comparative measurements taken
over tinle may accurately determine the stability of the
aneurysm. In my practice, we measure from the outer
wall to the outer wall. Anterior-to-posterior measurements
are obtauled from sagittal views, and transverse
measurements are obtauled from a left coronal view. I
avoid measurements in the axial view, since it is not
possible to determUle whether such measurements are
taken perpendicular to the long axis of the aorta, and
the lateral borders of the aorta are not well seen. In
addition, I believe that axial measurements are prone to
significant interobserver and intraobserver variability.

Front 28

Two views of the l iver in a patient with a h istory of l u ng cancer.
1 . Are the lesions shown in this case most likely solid or cystic?
2 . What is the most likely diagnosis?
3. What else should be considered?
4. How can the diagnosis be confirmed?

Back 28

liver Metastases
1 . The lesions shown in this case are homogeneous
and hypoechoic. There is no detectable posterior
enhancement, and the back wall is not sharply
defined. These characteristics are most consistent
with solid lesions. Cysts of this size in the liver
should appear anechoic with readily detectable
posterior enhancement. Occasionally, there is
overlap in the grey-scale appearance of solid and
fluid filled masses. In such cases, identification of
internal vascularity on color Doppler will indicate
that the lesion is solid.
2. The sonographic appearance is nonspecific.
However, they are not simple cysts and do not have
a typical appearance for hemangiomas. Given the
patient's history of lung cancer, these lesions are
most likely metastases.
3. Other possible causes of multiple solid lesions
include lymphoma and multifocal hepatocellular
cancer. Less likely considerations would be multiple
focal nodular hyperplasia, sarcoidosis, multifocal
adenomas, or abscesses. Hemangiomas are very
common and can be multiple, so they should also
be conSidered, although multiple hemangiomas that
were all hypoechoic would be very atypical.
4. The diagnosis of metastases can be (and in this case
was) confirmed with ultrasound-guided biopsy.
Reference
Marn CS, Bree RL, Silver TM: Ultrasonography of the
liver. Radiol Clin North Am 1 99 1 ; 29: 1 1 5 1 - 1 1 70.
Cross-Reference
Ultrasound: THE REQUISITES, pp 7-9.
Comment
Multiple solid hypoechoic masses in the liver are most
likely to be metastases. In the majority of cases, patients
with liver metastases have a prior history or current
evidence of an extrahepatic malignancy. This patient
had a history of lung cancer. If there were a history of
lymphoma, then the most likely diagnosis would be
lymphoma. If there were a history of fever and diverticulitiS,
liver abscesses would be a consideration. If there
were a history of hepatitis C, then multifocal hepatocellular
cancer would be most likely. In general, if there
is no history to point toward another diagnOSiS, then
metastatic disease is the leading possibility.
Further workup also depends on the patient'S history.
If there is a known primary malignancy and the presence
of metastatic disease needs to be confirmed prior
to chemotherapy, ultrasound-guided biopsy should be
performed. In this situation, fine needle aspiration with
3 2
cytologic evaluation is usually adequate. If there is n o
known primary malignancy, a standard evaluation for an
lmknown primary should be pursued. If the primary
malignancy is not found, then a liver biopsy should be
performed to establish the cell type that needs to be
treated. In this situation, core biopsies are usually necessary
to provide enough tissue so that immunohistochemical
studies can be obtained to better define possible
primaries. If the primary malignancy is found or if
other sites of metastases are identified, then biopsy of
the safest and most accessible site should be performed

Front 29

Transverse view of the right u pper q u adrant and the left l ower q u a d rant
in two patients.
1 . What do these patients have in common?
2. To what are the arrows pointing?
3. In what anatomic location is the asterisk positioned?
4. What are the best places to look when searching for this abnormality?

Back 29

Ascites
1 . Both demonstrate peritoneal fluid that is anechoic
and conforms to the structures in the area. This is
typical of ascites.
2. The arrows are pointing to loops of small bowel.
Notice the mesentery surrounded by ascites.
3. The asterisk is in the hepatorenal fossa, also called
Morrison's pouch.
4. The most common location for ascites is around the
liver, in the pelvis, and in the pericolic gutters.
Reference
Nguyen KT, Sauerbrei EE, Nolan RL: The peritoneum
and the diaphragm. In Rumack CM, Wilson SR, Charboneau
]W (eds): Diagnostic Ultrasound, 2nd ed. St.
Louis, Mosby, 1 998, p 50 1 -5 1 9.
Cross-Reference
Ultrasound: THE REQUISITES, P 50.
Comment
Ascites can be due to many underlying abnormalities,
including congestive heart failure, hypoalbuminemia,
portal hypertension, venous or lymphatic obstruction,
infection or inflammation, and neoplasms. Because the
peritoneal cavity is a continuum of multiple interconnecting
spaces, ascites can localize in a variety of locations.
Sonography is an excellent means of detecting
ascites and is used routinely to localize an optimum site
for paracentesis.
The best way to distinguish uncomplicated ascites
and loculated peritoneal fluid collections is to look for
the effect the fluid has on adjacent structures. Loculated
collections such as abscesses, hematomas, and pseudocysts
will displace and distort the structures around
them. As shown in these images, simple ascites conforms
to the shape of adjacent structures.

Front 30

Lo ngitudinal views of two patients with the same a b norma l ity.
1 . Describe the abnormality seen in both of these kidneys.
2. How good is ultrasound at making this diagnosis?
3. Is the abnormality seen in these kidneys likely to be seen on CT?
4. What are potential causes of shadowing in the kidney?

Back 30

Testicular Cysts
1 . Testicular cysts require no additional workup ,
provided they appear entirely sinlple on ultrasound.
2. Cysts are detected on approximately 1 0% of
testicular sonograms.
3 . Testicular cysts are more conunon in elderly men.
4. Testicular cysts are associated with tubular ectasia
of the rete testis.
Reference
Gooding GA, Leonhardt W, Steul R: Testicular cysts: US
findings. Radiology 1 987; 1 6 3 : 5 37- 540.
Cross-Reference
Ultrasound: THE REQUISITES, pp 435-439.
COffi1llent
Testicular cysts were once felt to be relatively rare lesions.
However, widespread use of ultrasound to evaluate
scrotal diseases has shown that they are actually
common. Series have shown that intratesticular cysts
are seen Ul approxinlately 1 0% of patients referred for
scrotal sonograms. They often occur near the mediastinum.
This is well demonstrated in the first image, where
the small cyst is immediately adjacent to the linear,
hyperechoic mediastinum. These cysts are often seen ill
patients with tubular ectasia of the rete testes, and both
conditions may be caused by some degree of outflow
obstruction of the semulal fluid. Testicular cysts range
Ul size but are usually small. Even when they are large,
testicular cysts are generally not palpable.
Like cysts elsewhere Ul the body, testicular cysts
should be anechoic, have a strong back wall reflection,
and demonstrate p osterior acoustic e nhancement.
When an intratesticular lesion meets these classic criteria
for a simple cyst, it requires no further evaluation.
When there are any solid components or septations, the
possibility of a cystic testicular neoplasm should be
considered, particularly if the lesion is palpable.

Front 31

Longitudina l views of the testis in two patients.
1 . Do these patients need further workup?
2. How common are these lesions?
3. Are they more common in young patients or in elderly patients?
4. With what condition are they sometimes associated?

Back 31

Testicular Cysts
1 . Testicular cysts require no additional workup ,
provided they appear entirely sinlple on ultrasound.
2. Cysts are detected on approximately 1 0% of
testicular sonograms.
3 . Testicular cysts are more conunon in elderly men.
4. Testicular cysts are associated with tubular ectasia
of the rete testis.
Reference
Gooding GA, Leonhardt W, Steul R: Testicular cysts: US
findings. Radiology 1 987; 1 6 3 : 5 37- 540.
Cross-Reference
Ultrasound: THE REQUISITES, pp 435-439.
COffi1llent
Testicular cysts were once felt to be relatively rare lesions.
However, widespread use of ultrasound to evaluate
scrotal diseases has shown that they are actually
common. Series have shown that intratesticular cysts
are seen Ul approxinlately 1 0% of patients referred for
scrotal sonograms. They often occur near the mediastinum.
This is well demonstrated in the first image, where
the small cyst is immediately adjacent to the linear,
hyperechoic mediastinum. These cysts are often seen ill
patients with tubular ectasia of the rete testes, and both
conditions may be caused by some degree of outflow
obstruction of the semulal fluid. Testicular cysts range
Ul size but are usually small. Even when they are large,
testicular cysts are generally not palpable.
Like cysts elsewhere Ul the body, testicular cysts
should be anechoic, have a strong back wall reflection,
and demonstrate p osterior acoustic e nhancement.
When an intratesticular lesion meets these classic criteria
for a simple cyst, it requires no further evaluation.
When there are any solid components or septations, the
possibility of a cystic testicular neoplasm should be
considered, particularly if the lesion is palpable.

Front 32

Pulsed Doppler waveforms from the common carotid artery.
1 . What do these two waveforms have in common?
2. Will this finding be eliminated by proper adjustment of the Doppler gain?
3. Will this finding be eliminated by proper adjustment of the Doppler scale?
4. Will this finding be eliminated by changing to a higher frequency probe?

Back 32

Doppler Aliasing Artifact
1 . Both of the waveforms show aliasing.
2. Doppler gain does not affect aliasing artifacts.
3. Increasing the Doppler scale can decrease or
eliminate aliasing.
4. Lower frequency probes may eliminate aliasing, but
higher frequency probes will make it worse.
Reference
Rubin JM: AAPM tutorial: Spectral Doppler US. Radiographies
1 994; 1 4 : 1 39- 150.
Cross-Reference
Ultrasound: THE REQUISITES, P 474.
Comment
A number of artifacts can affect the Doppler waveform.
One of the most common is the aliasing artifact. Aliasing
artifacts arise owing to a basic principle of sampling
theory that states that a periodic phenomenon must be
sampled at twice its own frequency to be accurately
reproduced. Sampling at less than twice the frequency
will result in generation of artifactually low or negative
frequency determinations. The classic example of
aliasing artifact occurs when a rotating wheel on a
movie appears to be rotating in the reverse direction.
Ti1is happens because the frame rate of the movie is
not twice the revolution rate of the wheel. The same
phenomenon occurs with pulsed Doppler when the
pulse repetition frequency is too low. TI1is results in
generation of artifactually negative frequency-shift information.
On an arterial signal, the first effect is truncation
of the systolic peaks with wrap-around of the peaks
below the base line. As aliasing becomes increasingly
severe, the result is multiple wrap-arounds, and, eventually,
the Doppler signal overlaps itself and becomes
completely non-arterial in appearance. As shown on
the second image, this occurrence can simulate noise.
Whenever this type of signal is encountered, the Doppler
scale should be increased in order to determine
if there is truly an arterial signal hidden within the
waveform.
Since the frequency shift itself is proportional to the
transmitted frequency, shifting to a lower frequency
probe may assist in overcoming aliasing artifacts. Scanning
at a larger Doppler angle also decreases the Doppler
frequency shift and may assist in eliminating the
aliasing artifact. When possible, scanning in another
position so that the vessel is closer to the transducer
allows the pulse repetition frequency to be increased,
because the distance that the sound has to travel to
reach the vessel and return to the transducer is decreased.
Finally, some manufacturers have a function
whereby pulse repetition frequency is increased by
36
transmitting a sound pulse before the previous sound
pulse returns to the transducer. This allows for larger
Doppler scales but also creates one or more additional
sample volumes that can result in some ambiguity as to
the origin of the received Doppler signal.

Front 33

Lon g itud inal g rey-scale view and tra nsverse power Doppler view of the
proximal fifth finger.
1 . What are the pertinent findings?
2. What is the role of ultrasound in making this diagnosis?
3. What limits the ability of ultrasound to make this diagnosis?
4. How accurate is ultrasound in establishing this diagnosis in the hand and wrist?

Back 33

Foreign Body
1 . The grey-scale view shows a small echogenic
structure in the soft tissue of the finger with a faint
posterior shadow. The power Doppler view shows
a linear echogenic structure with intense
surrounding hyperemia.
2 . Ultrasound is used to look for radiolucent foreign
bodies. These include wood, glass, and plastic.
Ultrasound is also used to localize foreign bodies for
resection.
3. Size, depth, and composition of the foreign body
limit the ability of ultrasound to make this
diagnosis.
4. Very good. Sensitivity is about 95%.
Reference
Bray pw, Mahoney JL, Campbell JP: Sensitivity and specificity
of ultrasound in the diagnosis of foreign bodies
in the hand. ] Hand Surg 1 995;20CA) :661 -666.
Cross-Reference
Ultrasound: THE REQUISITES, P 4 5 5 .
Comment
Foreign bodies retained after trauma can be a source
of chrOl1ic pain or infection. Many foreign bodies are
radio-opaque and can be detected and localized with
radiographs. Those that are not radio-opaque can usually
be seen with ultrasound. In the study of cadaveric hands
and wrists referenced with this case, B ray and colleagues
showed that sonographic detection of foreign
bodies was excellent for objects between 1 X 4 mm
and 2 X 5 mm. Visualization was 1 00% for all objects
placed in the palm except for small glass particles.
Visualization ranged from 79% to 1 00% for different
types and sizes of foreign bodies placed in the fingers.
All foreign bodies appear as bright reflectors. They
may or may not be associated with an adjacent hypoechoic
inflammatory process or an adjacent abscess.
Acoustic shadowing may be seen if the foreign body is
large enough to block a significant amount of the ultrasound
beam. Glass or metallic objects may show ringdown
or comet-tail artifacts. If adjacent inflammation
is present, color or power Doppler may demonstrate
surrounding hyperemia, as seen in this case.

Front 34

Long itudinal and tran sverse views of the thyroid i n two patients.
1 . Are the nodules shown in these patients most likely benign or malignant?
2. What is the incidence of thyroid nodules in the population?
3 . What is the role of ultrasound in the evaluation of a thyroid nodule?
4. What gauge needle should be used for fine-needle aspiration of the thyroid?

Back 34

Nodular Hyperplasia of the Thyroid
1 . The nodule on the left is mostly solid and has a
small cystic area and a uniform, thin, hypoechoic
halo. The second nodule is mostly cystic and has
thick, irregular septations. In thyroid nodules, all of
these characteristics favor a benign etiology.
2 . The incidence is roughtly equal to the age of the
population that is studied.
3. The role of ultrasOlmd in diagnosing thyroid
nodules is: 1) to confirm that the nodule is in the
thyroid; 2) to guide biopsy; 3) to monitor the
response of the nodule to treatment; 4) to look for
occult disease.
4. Usually a 25-gauge needle is used to perform fineneedle
aspiration of thyroid nodules.
Reference
Solbiati L, Livraghi T, Ballarati E, et al: The Thyroid. In
Solbiati L, Rizzatto G (eds): Ultrasound of Superficial
Structures. Edinburgh, Churchill Livingstone, 1 995,
49-86.
Cross-Reference
Ultrasound: THE REQUISITES, pp 448-45 1 .
Comment
The most common indication for thyroid ultrasound is
nodular thyroid disease. Approximately 80% of nodules
are due to hyperplasia, which may be related to iodine
deficiency, familial causes, or medications. An enlarged,
hyperplastic gland is called a goiter. The male-to-female
ratio is approximately 1 :3 . When hyperplasia progresses
to nodule formation, the pathologic designation of the
nodules may be hyperplastic, adenomatous, or colloid.
These nodules have a wide range of sonographic appearances.
They are often isoechoic or hyperechoic compared
to the normal parenchyma. They may have a thin,
uniform, hypoechoic halo due to compressed parenchyma
or surrounding vessel s . They very frequently
have cystiC components due to degeneration and hemorrhage.
Bright foci, often with comet-tail artifacts,
may be present and indicate inspissated colloid. Multiple
internal septations and mural nodules can be seen.
Benign adenomas accOlmt for approximately 5% to
1 0% of thyroid nodules. A small minority may cause
hyperthyroidism owing to autonomous function. They
are usually solitary but may occur in a gland that has
multiple nodules for other reasons. Follicular adenomas
and follicular cancer can be distinguished only on the
basiS of vascular and capsular invasion. Therefore, fineneedle
aspiration that indicates the presence of a follicular
lesion should be followed by surgical resection.
Autopsy studies have shown that 50% of patients
with a clinically normal thyroid have nodules. Sonography
detects nodules in approximately 40% of patients
who are scanned for other reasons. Despite the high
38
prevalence of tllyroid nodules, the percentage of thyroid
malignancy is very low (2% to 4%). Therefore it is not
practical to biopsy every nodule that is detected. This
is especially true of incidentally detected nodules in
patients being scanned for other reasons. Published indications
for performing biopsies inclu d e : 1 ) nodules
greater than 1 . 5 cm in size undergo biopsy regardless of
the sonographic appearance; 2) nodules with malignant
features on sonography, including microcalcifications,
irregular margins, or thick halo, undergo biopsy regardless
of size; 3) nodules less than 1 . 5 cm in size can be
followed by regular physical examination, provided they
do not have malignant sonographic features.

Front 35

Longitu d i na l views of the right kidney.
1 . What causes the anterior, triangular, echogenic defect at the junction of the upper and mid thirds of
this kidney?
2. How often is this seen?
3. Is it more commonly visualized on the right or left kidney?
4. What further evaluation is needed?

Back 35

J u nctional Paren chymal Defect
1 . The defect is called the junctional parenchymal
defect or the inter-renuncular junction.
2. It is visualized in approximately 20% of patients.
3. It is more commonly seen on the right side.
4. This requires no additional evaluation.
Reference
Carter AR, Horgan JG, Jennings TA, Rosenfield AT: The
j unctional parenchymal defect: A sonographic variant
of renal anatomy. Radiology 1 985 ; 1 54:499-502.
Cross-Reference
Ultrasound: THE REQUISITES, P 73.
Comment
Longitudinal views of the right kidney frequently show
a triangular-shaped defect along the anterior renal surface
at the junction of the upper and middle third. Less
commonly, the defect is seen on transverse scans. This
is a normal variant located at the point of fusion of the
embryologic upper and lower renunculus. It occurs
equally often in both kidneys, but is sonographically
seen less often on the left because acoustic access to
the left kidney is more lintited, and views from an
anterior approach are seldom obtained.
The typical sonographic features of the junctional
parenchymal defect are its triangular shape, its location
at the upper to mid kidney, and its communication with
the renal sinus fat. This communication is best visualized
by following the defect medially on longitudinal
views. In some cases, it is connected to the sinus by a
thin, echogenic line. In other cases, the connection may
be broader. This is demonstrated in the second image
of this case. These characteristics should allow for a
definitive distinction from other peripheral echogenic
leSions, such as cortical scars or angiomyolipomas.

Front 36

Transverse scan of the pan creas and longitudinal scan of the common
bile d u ct in two patients.
1 . What do these patients have in common?
2. Is tllis abnormality typically hypoechoic?
3. Would other imaging tests be useful?
4. What is the most common location of this lesion?

Back 36

Adenocarcinoma of the Pan creas
1 . Both patients have a focal pancreatic mass. The
mass in the second image is located in the
pancreatic head and is obstructing the bile duct.
2. Most abnormalities of the pancreas are hypoechoic,
and pancreatic cancer is no exception.
3 . CT would be useful to look for evidence of
metastatic disease. ERCP would be useful to look at
the pancreatic duct and potentially to establish a
histologic diagnosis with brush biopsies.
4. Approximately 70% are located in the head, 20% in
the body, and 5% in the tail of the pancreas. Diffuse
involvement of the pancreas is also possible.
Reference
Karlson B-M, Ekbom A, Lindgren PG, et al: Abdominal
US for diagnosis of pancreatic tumor: Prospective
cohort analysis. Radiology 1 999; 2 1 3 : 1 07- 1 1 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 33 - 1 36.
Comment
Pancreatic cancer is the fourth most common cause of
cancer death in the United States. The prognosis is
dismal, with a I -year survival rate of approximately 1 0%.
Only 1 5% of tumors are potentially resectable, and even
in patients who undergo Whipple resection for cure,
the 5-year survival rate is only 20%. Patients present
most often with jaundice due to bile duct obstruction.
Weight loss, pain, vomiting, unexplained venous thrombosis,
and malabsorption are among the other possible
symptoms. The vast majority of pancreatic adenocarcinomas
arise from the ductal epithelium.
The typical sonographic appearance is of a poorly
marginated hypoechoic mass. Most are homogeneous,
but as they enlarge, they may become heterogeneous.
Echogenic cancers are rare. The majority of pancreatic
cancers arise in the head or uncinate process, and these
lesions are often quite small, since they maniiest early
with bile duct obstruction and jaundice. Lesions in the
body and tail tend to be larger. The average size of this
tumor is 2 to 3 cm.
Although pancreatic cancer is by far the most common
pancreatic tumor, other tumors should be considered
when a focal hypoechoic solid mass is detected.
Metastases to the pancreas and pancreatic lymphoma
both appear as hypoechoic masses. These masses are
often multiple, and the majority of these patients have
a prior history of lymphoma or an extrapancreatic malignancy.
Microcystic adenomas may appear solid on sonography,
but they lack any evidence of metastases and
appear cystic on CT. Focal pancreatitis can also produce
40
a hypoechoic inflanunatory mass in the pancreas that
can simulate cancer. Fortunately a history of pancreatitis
is usually present in these patients

Front 37

Transverse grey-sca le and power Doppler views of the m id aspect of the
left testis.
1 . Describe the important findings in tills case.
2. What are some of the potential complications of this condition?
3. What symptoms is this patient likely to have?
4 . Is this condition usually diffuse or focal?

Back 37

Epid idymitis
1 . There is marked enlargement of the body of the
epididymis and intense hypervascularity of the
epididymis when compared to the testis. This is
typical of acute epididymitis.
2. Epididymitis can progress to cause an abscess, a
pyocele, orchitiS, or testicular ischemia.
3. Symptoms of epididymitis include primarily pain
and swelling of the scrotum, possibly with fever
and other signs of lower genitourinary tract
infection.
4. Epididymitis can be either focal or diffuse. When
focal, it is important to survey the entire epididymis
from head to tail to make the diagnosis.
Reference
Horstman WG, Middleton WD, Melson GL: Scrotal inflammatory
disease: Color Doppler ultrasonographic
findings. Radiology 1 99 1 ; 1 79:55-59.
Cross-Reference
Ultrasound: THE REQUISITES, pp 445-446.
Comment
Epididymitis is the most common cause of scrotal pain
and swelling in postpubertal men. It usually arises from
an i.nfection elsewhere in the lower urinary tract, such
as prostatitis. Other etiologies include hematogenous
spread and trauma. Common organisms are Escherichia
coli, Pseudomonas, and Aerobacter. In younger men,
Gonococcus and Chlamydia are also common.
On sonography, epididymitis produces an enlarged
and hypervascular epididymis . The process may be diffuse
or may be localized to just the head or the tail of
the epididymis. Isolated involvement of the tail can be
overlooked if careful scanning of the inferior scrotum is
not performed. In most cases, the epididymis becomes
hypoechoic. Occasionally, a mixed echogenic appearance
develops, perhaps due to edema in the structures
adjacent to the epididymiS. It is important to realize
that the hyperemia generally precedes the grey-scale
changes. Therefore, color Doppler is more sensitive to
epididymitis than grey-scale sonography. In addition to
epididymitis, another common cause of an enlarged
epididymiS is post-vasectomy changes. This can be distinguished
because it is bilateral and is not hyperemic

Front 38

Transverse view of the pelvis j ust a bove the bladder trigone and
longitudina l view of the pelvis just to the left of the midline in a patient
who is 1 8 weeks preg nant.
1 . Describe the abnormality shown in this patient.
2. What is the role of ultrasound in making this diagnosis?
3. When considering the diagnosis shown in this patient, where is the best place to look initially?
4. Is this abnormality easier to see in men or in women?

Back 38

Distal U reteral Stone
1 . The transverse view shows an echogenic shadowing
structure in the left pelvis in the expected location
of the distal ureter. The longitudinal view shows
the same abnormality and confirms that it is located
in the ureter.
2 . Ultrasound is generally not used as a primary means
of evaluating patients with suspected ureteral
stones. The exception is when the patient is
pregnant and radiation needs to be avoided.
3. The majority of ureteral stones impact in the distal
ureter. Therefore, views through the urinary
bladder give the highest yield for stone detection.
4. Stones in the distal ureter are seen with similar
success in men and in women using transabdominal
scanning through the fluid-filled bladder. In women,
transvaginal sCanning can be used to sort out
difficult cases.
Reference
Olutishi K, Watanabe H, Ohe H, Saitoh M: Ultrasound
findings in urolithiasis in the lower ureter. Ultrasound
Med Biol 1 986; 1 2 : 577-579.
Cross-Reference
Ultrasound: THE REQUISITES, pp 103- 1 04 .
Comment
Patients with renal colic can be imaged in a number
of ways. Traditionally, intravenous urography was the
method of choice. Currently, noncontrast CT is the
recommended first test since it avoids the small risk of
reactions to contrast media and provides information
about structures other than the kidneys, ureters, and
bladder. Ultrasound has a very limited role in the initial
workup of patients with suspected renal colic. Tllis is
not to say that ultrasound is not capable of establishing
the correct diagnosis in the majority of patients. It is
simply easier and more effective to start with other
tests. One legitimate role of ultrasound is in the pregnant
patient in whom radiation needs to be avoided.
Most, but certainly not all, patients who are passing
a kidney stone will have at least mild hydronephrosis.
They may also have a small amount of perinephric fluid,
usually best seen around the upper or lower pole. In
the proper clinical setting, either of these findings is
very specific for ureteral stones. Identification of the
ureteral calculus itself is easiest when it is in the proximal
ureter near the ureteropelvic junction (using the
kidney as a window), and in the distal ureter near the
ureterovesicle junction (using the fluid-filled bladder as
a window). The most common place for stones to impact
is in the distal ureter, so it is very important to
42
carefully evaluate the distal ureters. In addition to a
transabdominal approach using the bladder as a window,
the distal ureters in women can be imaged quite
well from a transvaginal approach. In men, a transrectal
approach can be used, although it is not as successful
as the transvaginal approach in women.

Front 39

Tra nsverse views of the groin and mid thi g h .
1 . How good i s ultrasound a t malting this diagnosis in the thigh?
2. Is it possible to make this diagnosis reliably without color Doppler?
3. Does this condition most commonly produce unilateral or bilateral symptoms?
4. How important is luminal echogenicity in establishing the diagnosis?

Back 39

Lower Extremity Deep Vein Thrombosis
1 . Ultrasound is very good at diagnosing deep vein
thrombosis (DVT) in the femoral-popliteal system .
2 . Color Doppler plays a minor role in diagnosing
DVT. It is usually evaluated completely with greyscale
imaging.
3. Lower extremity DVT is usually unilateral.
4. The diagnosis of DVT is made based on lack of
venous compressibility. Detection of intraluminal
echoes is not a reliable way to diagnose DVT, and
lack of intraluminal echoes is not a reliable way to
exclude DVT.
Reference
Fraser ]D, Anderson DR: Deep venous thrombosis: Recent
advances and optimal investigation with US.
Radiology 1 999;2 1 1 :9-24.
Cross Reference
Ultrasound: THE REQUISITES, pp 483-48 5 .
Comment
Ultrasound has become the procedure of choice in the
evaluation of suspected lower extremity DVT. In symptomatic
patients, the sensitivity and specifiCity exceed
95% and 98%, respectively, in the femoral-popliteal system.
Results in asymptomatic ltigh-risk patients (predominantly
post hip and knee surgery) and in the calf
are more variable.
Normally, the deep veins should be completely compressible.
The diagnosis of DVT is made when the veins
fail to compress completely. Many normal veins will
have low level internal echoes that are artifactual, and
it is not uncommon for an intraluminal clot to be hypoechoic
or anechoic. Therefore, analysis of echogenicity
is not a primary focus of lower extrentity venous examinations.
In patients with marked obesity or with severe
edema, identification of the femoral and popliteal veins
may be very difficult. In these situations, color Doppler
may help to localize the vessels. Augmentation of proximal
venous flow by compression of the calf or plantarflexion
can accentuate the veins and further assist
when color Doppler is required.

Front 40

long itu dinal color Doppler view of the carotid bifu rcation and p u l sed
Doppler waveforms from the i nternal and extern al carotid a rteries. (See
color plates.)
1 . Identify the internal and the external carotid arteries on the color Doppler image.
2. Which vessel is typically located anterior and medial?
3. Which waveform is from the internal and which is from the external carotid artery?
4 . On longitudinal views of the bifurcation, is the internal carotid artery located superficial or deep to
the external carotid?

Back 40

N ormal Carotid Bifurcation
1 . Branches arise from the deep vessel, so that vessel
is the external carotid artery. The larger vessel
without branches is the internal carotid artery.
2. The external carotid artery is located anterior and
medial to the internal carotid.
3. The top waveform shows a low resistance pattern
typical of the internal carotid artery. The bottom
waveform shows rapid pulsations in the last two
cardiac cycles due to manual tapping on the
superficial temporal artery. This is a way of
identifying the external carotid.
4. When the transducer is positioned in the anterior
and medial neck, the external carotid artery will be
superficial. When the transducer is positioned in
the posterior and lateral neck, the internal carotid
will be superficial.
Reference
Cardoso T, Middleton WD: Duplex sonography and
color Doppler of carotid artery disease. Semin Interv
Radiol 1 990;7: 1 -8.
Cross-Reference
UlttC:lsound: THE REQUISITES, pp 470-473.
Comment
Proper interpretation of carotid artery Doppler examinations
requires reliable differentiation of the internal and
external carotid arteries. Several features distinguish
these vessels. Location, size, and branches are all useful.
Realize, however, that although branches are always
present on the external carotid artery, they are not
always detectable on color Doppler. Therefore,
branches are useful only when they are seen.
Doppler waveform analysis is also a valuable means
of distinguishing the internal and external carotids.
Since the internal carotid supplies a solid organ with a
low vascular resistance, its waveform has a low resistance
profile with broad systolic peaks, gradual systolic
deceleration into early diastole, and well-maintained diastolic
flow throughout the cardiac cycle. The external
carotid supplies primarily muscle, bone, and cutaneous
tissue, which has a high resistance to blood flow. Therefore
the external carotid waveform has narrower systolic
peaks, more abrupt transition between systole and diastole,
and less end-diastolic flow. Another feature of the
waveform that can be useful is transmission of fluctuations
into the external carotid when the superficial
temporal artery is tapped. This is called the temporal
tap maneuver. Although the effects tend to be greatest
and most frequent in the external carotid, occasionally
some changes can be seen in the internal and in the
common carotid.

Front 41

long itud inal g rey-sca le and color Doppler i mages of the testis. (See
color plates.)
1 . Describe the abnormality.
2 . What nonneoplastic conditions can appear as a focal hypoechoic mass in the testis?
3. Are testicular tumors most likely benign or malignant?
4 . Does associated enlargement and hypervascularity of the epididymis favor a neoplastic or
nonneoplastic condition?

Back 41

Testicu lar Sem inoma
1 . The unages show a homogeneous, hypoechoic,
hypervascular mass. The most likely diagnosis is a
testicular tumor, and the appearance is typical for a
seminoma.
2. Infarcts, focal atrophy, focal orchitis, hematoma,
abscess, sarCOid, and contusions can all appear as a
hypoechoic lesion.
3. Testicular tumors are much more likely to be
malignant than benign.
4. Involvement of the epididymis favors epididymoorchitis.
Reference
Horstman WG, Melson GL, Middleton WD, Andriole GA:
Color Doppler ultrasonography of testicular tumors.
Radiology 1 992; 1 85:733-737.
Cross-Reference
Ultrasound: THE REQUISITES, pp 439-442.
Comment
Primary testicular tumors are the most common malignancy
Ul young adult males. Germ cell tumors account
for the vast majority of testicular tumors. SemulOma is
the most common germ cell tumor, accounting for 40%
to 50% of these malignancies. Seminomas frequently
occur in a pure form as well as in mixed germ cell
tumors. They tend to occur Ul a slightly older age group
than the other germ cell tumors. Although 25% of patients
with pure seminomas have metastases at the time
of presentation, the 5-year survival rate is excellent.
Most testicular tumors manifest as a painless, palpable
mass. Approximately 10% will manifest with testicular
pain and another 1 0% with symptoms related to metastatic
disease (such as back pain due to retroperitoneal
adenopathy).
On sonography, detection of an intratesticular lesion
other than a SUllple cyst should always raise the possibility
of a testicular tumor. Pure semulOmas are typically
homogeneous, hypoechoic, solid masses. When they are
large, they tend to become more heterogeneous. Cystic
components and calcification are distinctly uncommon
in pure semUlomas.
With modern color Doppler, most testicular tumors
larger than 1 cm (and many that are less than 1 cm) are
seen to have detectable ulternal blood flow. Detecting
internal flow can be helpful in maki.tlg a diagnosis, SUlce
many benign intra testicular lesions that can potentially
be confused with tumors, such as hematomas , abscesses,
and ulfarcts, do not have ulternal flow. In addition,
many nonneoplastic lesions that are readily seen
on ultrasound are not palpable, while the majority of
testicular tumors are palpable.

Front 42

Longitud inal views of the rig ht and left u pper quadrants i n two patients.
1 . What are the major complications of the condition shown in this case?
2. What other associated findings are there?
3. Would your diagnosis be the same if there were no family history of renal disease?
4. Is there any effective therapy?

Back 42

Autosomal Dominant Polycystic Kid ney
Disease
1 . The most devastating complications of polycystic
kidney disease (PKD) are renal failure and
hypertension. Patients are also at increased risk for
cyst hemorrhage, renal infection, and stone
formation
2. Findings besides renal cysts include cysts in the
liver (and rarely in the pancreas) and berry
aneurysms.
3. Up to 50% of cases of PKD are due to spontaneous
mutations and have no family history.
4. There is no proven therapy. Laparoscopic cyst
decortication can help relieve symptoms and may
improve renal function.
References
Levine E, Hartman DS, Meilstrup Jw. et al: Current
concepts and controversies in imaging of renal cystic
diseases. Urol CUn North Am 1 997;24 : 523-544.
Ravine D, Gibson RN, Walker RG, et al: Evaluation of
ultrasonographic criteria for autosomal dominant
polycystic kidney disease 1 . Lancet 1994; 343:824.
Cross-Reference
Ultrasound: THE REQUISITES, pp 86-87.
Comment
Autosomal dominant PKD is an inherited disorder that
has 1 00% penetrance but is expressed to varying degrees.
Patients generally present in the fourth or fifth
decade with symptoms related to the mass effect of
enlarged kidneys, hypertension, hematuria, or urinary
tract infections. Renal failure develops on average in the
sixth decade of life. Up to 10% of cases of end-stage
renal disease in North America and Europe are due to
PKD. If untreated, patients survive approximately 1 0
years from the onset of symptoms.
Two genetic defects cause PKD. Type 1 accounts for
approximately 90% of families and is due to a defect on
the short arm of chromosome 16. Type 2 is caused by
a defect on the long arm of chromosome 4 and accounts
for 1 0% of families. The major clinical difference in
these two types is the lower age of onset of end-stage
renal disease in type 1 than in type 2 .
Although the kidneys are affected t o a greater degree
than any other organ, cysts can also develop in the liver
(in up to 50% of patients), the pancreas (in up to 7% of
patients), and the spleen (in less than 5% of patients).
Cysts in these organs rarely cause clinical symptoms. In
particular, the liver can be almost replaced by multiple
cysts and still function normally. Approximately 10% of
patients have intracranial aneurysms.
46
On sonography, the diagnosis is made by detecting
multiple, bilateral renal cysts located in the renal cortex.
In older patients the kidneys are almost always enlarged,
sometimes to the point that they cannot be effectively
measured with sonography. Hemorrhage into renal cysts
is very common and may result in !')w level internal
echoes, fluid-blood levels, or solid nodular internal
structures. Cyst wall calcification and renal stones are
also common.
In affected families, it is common to screen children
to determine whether they inherited the disease. Criteria
that have been established include the presence of
at least two cysts in one kidney or one cyst in each
kidney in an at-risk person under 30 years of age, the
presence of at least two cysts in each kidney in an atrisk
person between 30 and 59 years of age, and at least
four cysts in each kidney for persons at risk aged 60
years and older. Most patients have many cysts present
bilaterally, and the diagnosis is not in doubt. Ultrasound
has a high sensitivity in making the diagnosis in patients
with type 1 disease and in patients with type 2 disease
who are over 30 years old. Ultrasound is less sensitive
in patients with type 2 disease who are less than 30
years aIel. When ultrasound results are indeterminate or
are confUSing, DNA linkage analysis can be performed
if it is available.

Front 43

Lon g itudinal and transverse views of the g a l lbladder in a patient with
fever.
1 . What are the abnormalities in the images shown above?
2 . What is the differential diagnosis?
3. What is the preferred way of establishing this diagnosis?
4. What is the treatment of choice?

Back 43

Acute Cholecystitis
1 . The gallbladder is enlarged ( 1 2 cm X 7 cm), has a
thick wall (5 mm), and has an intrallUninal stone.
2. The most likely diagnosis is acute cholecystitis.
Many things can cause wall thickening, including
edema-forming states, portal hypertension,
hepatitis, adenomyomatosis, and gallbladder cancer.
But the association of gallbladder enlargement,
stones, and wall thickening in a febrile patient is
strongly predictive of acute cholecystitis.
3. Ultrasound is the best initial test in patients with
suspected acute cholecystitis. Scintigraphy is also
very helpful in a problem-solving mode when the
sonogram is confusing or indefinite.
4. Surgery. In some cases surgery will be postponed
until the patient has been treated with antibiotics,
and the acute inflammatory changes have resolved.
Reference
Middleton WD: Right upper quadrant pain. In Bluth
EI, Benson C, Arger P, et al (eds): Tbe Practice oj
Ultrasonograpby. New York, Thieme, 1 999, pp 3 - 1 6.
Cross-Reference
Ultrasound: THE REQUISITES, pp 4 1 -4 5 .
Conunent
Ultrasound is the procedure of choice in the evaluation
of patients with suspected acute cholecystitis. In the
majority of patients, by documenting a gallstone-free
gallbladder, ultrasound can exclude the diagnosis rapidly
and effectively. This is important, since most patients
with suspected acute cholecystitis do not actually have
that problem. Ultrasound has also been shown to be as
effective at establishing the diagnosis of acute cholecystitis
as any other noninvasive technique.
The signs of acute cholecystitis are gallstones, wall
thickening (greater than 3 mm), gallbladder enlargement
(greater than 4 cm transverse diameter), pericholecystic
fluid, an impacted stone in the gallbladder neck
or cystic duct, and a positive sonographic Murphy's
sign. The combination of stones and either wall thickerling
or a positive sonographic Murphy's sign has a very
high positive predictive value for acute cholecystitis.
Cholescintigraphy can also be used in patients with
suspected acute cholecystitis. Accuracy is similar to ultrasound.
However, there are several limitations to scintigraphy.
Cholescintigrtl.phy does not give morphologic
information about the gallbladder (such as gallbladder
size, wall thickness, pericho!ecystic abscess formation,
or presence and size of stones), which is important
prior to laparoscopic cholecystectomy. It also fails to
provide information about other organs that might account
for the patient's problem when the gallbladder is
48
normal. Finally, it is more time-consuming and expensive
than sonography. Because of these limitations,
cholescintigraphy is generally not the initial exanlination
in patients with suspected cholecystitis. Nevertheless,
it is a very good way to evaluate patients who have
equivocal or confusing findings on ultrasound.

Front 44

Views of the testis i n two patients.
1 . What is the significance of the shadowing shown in the first image?
2 . In patients such as these, what else should be scanned in addition to the scrotum?
3. Is scrotal MRI useful in patients with sonographic findings such as these?
4. What conditions predispose to this abnormality?

Back 44

M ixed Germ Cell Tumors
1 . The shadowing indicates calcification, which is rare
in pure selninomas but is common in mixed germ
cell tumors.
2 . In a patient with what appears to be a testicular
tumor, it is helpful to scan the retroperitoneum to
look for adenopathy.
3 . Scrotal MRl is needed only rarely following scrotal
ultrasound and would not add any valuable
information in cases such as these.
4. Cryptorchidism, testicular atrophy, prior testicular
tumor, and maybe microlithiasis predispose to
testicular tumors.
References
Choyke PL. Dynamic contrast-enhanced MR imaging of
the scrotum: Reality check. Radiology 2000 ; 2 1 7 :
1 4 - 1 5 .
Horstman WG: Scrotal imaging. Urol Clin Nortb A m
1 997; 24:653-67 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 439-440.
Conunent
Of primary tumors of the testis, 95% are malignant
germ cell neoplasms. These tumors are divided into
seminomas and nonselninomas. Tumors that are composed
of a mixture of seminomatous elements and nonseminomatous
elements are grouped with the nonsenlinomas.
Nonseminomatous tumors include teratoma,
choriocarcinoma, embryonal cell carcinoma (also refen-
ed to as yolk sac tumors and endodermal sinus
tumors in the pediatric age group), and any combination
of these tumors. Teratocarcinoma refers to the relatively
common combination of teratoma and embryonal cell
carcinoma.
Unlike most seminomas, which are homogeneous
and hypoechoic, nonseminomatous tumors are usually
heterogeneous. This is at least partly due to the frequency
of hemorrhage and necrosis. In addition, they
often have cystic areas as well as calcifications. Cystic
areas are most frequently seen in tumors that contain
teratomatous elements.

Front 45

Lon g itudinal views of the porta hepatis i n two patients. The first i m age
is from a 2 1 -year-old man and the second i s from a 65-year-old woman.
1. Which o f the patients shown in this case i s more likely t o have biliary obstruction?
2. Is the common duct frequently ectatic following a cholecystectomy?
3. How sensitive is ultrasound in determining the level and cause of biliary obstruction?
4. What is the theory behind giving patients a fatty meal when biliary obstruction is suspected?

Back 45

Extrahepatic B i l iary Dilation
1. Both itnages show dilated common bile ducts. In
the second linage, the duct is dilated in its mid
portion, but it tapers to a normal caliber distally
and proximally. In the first itnage overlyitlg gas
obscures the distal duct, but the proximal duct is
dilated where it crosses over the right hepatic
artery. Because of this, it is more likely to be
obstructed. Additional images showed distal duct
stones in the first patient and no abnormalities in
the second patient.
2. The size of the extrahepatic duct itlcreases with age
and following a cholecystectomy. Therefore, an
enlarged duct is less concerning in these patients.
3. Reports indicate that sensitivities up to 80% to 90%
can be obtained with good technique.
4. A fatty meal stimulates bile production by the liver
and contraction of the gallbladder. In patients with
obstruction, this results in enlargement of the duct.
Fatty meals also stitnulate relaxation of the
sphincter of Oddi, so that there is no change or
reduction itl the size of the duct in patients who do
not have obstruction. Intrinsic variability in
measurements of the bile duct diameter often limits
the use of this technique.
Reference
Middleton WD: The bile ducts. In: Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1 993, pp 1 46- 1 7 2 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 59-6 1 .
Comment
Diagnosis of bile duct obstruction with sonography depends
on detection of ductal dilatation. Different studies
have proposed different measurements for the upper
limits of normal for the extrahepatic ducts. Unfortunately,
some obstructed ducts may not be dilated, and
many things other than obstruction can cause dilated
ducts. Therefore, rigid reliance on any single measurement
value is dangerous. Important factors to realize
when analyzing the common duct is that the duct normally
enlarges with age (due to degeneration of the
elastic fibers in the wall) and often enlarges following a
cholecystectomy (this is controversial). Thus, borderline
enlarged ductal measurements are more likely to indicate
obstruction in young patients and itl patients with
their gallbladders than in older patients or patients who
have had a cholecystectomy. In addition, it is not uncommon
for the common duct to be ectatic in its mid
portion between the liver and the head of the pancreas.
50
Therefore, if the duct is of normal caliber proxitnally
where it crosses the right hepatic artery and distally
within the head of the pancreas, then measurements
slightly above the normal range in the mid segment are
much less likely to indicate obstruction. With these
caveats in mind, a reasonable value to use as the upper
litnits of normal for the maximum duct diameter is 6
mm. Some experts use 5 mm as the upper llinits of
normal and allow an additional 1 mm for each decade
beyond age 50. In other words, a 5-mm duct is normal
at age 50; a 6-mm duct is normal at age 60, and so forth.

Front 46

Long itud inal views of the kid ney i n two patients.
1 . Is ultrasound a good means of characterizing lesions such as the ones shown here?
2 . What are the three characteristics of this lesion?
3. What other lesions should be included in the differential diagnosis?
4. How common are these lesions?

Back 46

Renal Cysts
1 . As itl other parts of the body, ultrasound is an
excellent way to evaluate the characteristics of
cystic renal lesions.
2 . Characteristics of a simple cyst include lack of
internal echoes, well-defined back wall, and
posterior acoustic enllancement.
3. Lesions that can simulate a simple cyst itlclude
calyx diverticulum, aneurysm, pseudoaneurysm,
lymphoma, or upper pole duplication.
4. Approximately 50% of patients over age 50 have at
least one renal cyst.
Reference
Curry NS, Bissada NK: Radiologic evaluation of small
and indeterminant renal masses. Ural Clin North A m
1997;24:493-505.
Cross-Reference
Ultrasound: THE REQUISITES, pp 8 1 -84.
Comment
Renal cysts are extremely common. Provided they satisfy
the classic sonographic criteria for cysts, renal cysts
reqUire no further evaluation. It is important to realize
that all three of the criteria for cysts may not be seen
on all linages of the cyst. For instance, the linage that
shows itlcreased tlu'ough transmission may not demonstrate
an anechoic lumen. As long as the three criteria
can be shown on a group of images, then a confident
diagnosis of a cyst can be made.
A common dilemma is a cyst that appears to contain
mternal echoes. Internal echoes may be real or may be
artifacts created by the body wall. Imagmg from multiple,
different approaches varies the interactions from
overlying tissues and often helps to clear out the internal
artifacts. These types of artifacts can also be dramatically
reduced or completely elitninated through the use
of tissue harmonic linagitlg.

Front 47

Transverse view of the pancreas and left u pper quadrant i n two patients
with the same abnorm al ity.
1 . What question would you want to ask these patients?
2. How often do pancreatic adenocarcinomas have cystic components?
3. Does the differential diagnosis vary if the patient is a man or a woman?
4. Are pseudocysts more common in alcohol-induced or in gallstone-induced pancreatitis?

Back 47

Pancreatic Pseudocysts
1 . In patients with cystic lesions of the pancreas, it is
important to know whether they have a history of
pancreatitis.
2 . Cystic areas are rare in adenocarcinoma of the
pancr s.
3. Women have a higher risk of cystic pancreatic
neoplasms.
4. The large majority of pseudocysts are due to
alcoholic pancreatitis.
Reference
Ros PR, Hamrick-1\uner ]E, Chiechi MY, et al: Cystic
masses of the pancreas. Radiographies 1992; 1 2 :672-
686.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 26- 1 29.
Comment
Pancreatitis has a number of potential complications.
The list of local complications potentially seen on sonography
includes fluid collections, pseudocysts, abscesses,
necrosis, pseudoaneurysms, venous thrombosis,
and biliary obstruction. Fluid collections within or
around the pancreas occur in 40% to 50% of patients
with pancreatitis. The majority of fluid collections resolve
spontaneously. If the collection organizes and
forms a fibrous capsule, it is referred to as a pseudocyst.
It takes approximately 6 weeks for a fluid collection to
mature into a well-encapsulated pseudocyst. Approximately
2% to 1 0% of patients with acute pancreatitis
ultimately develop a pseudocyst.
Pseudocysts can occur almost anywhere, but they are
most commonly seen within or immediately adjacent to
the pancreas. They appear as well-defined masses that
are usually anechoic or hypoechoic. Pseudo cysts may
contain internal debris, hemorrhage, or septations. In
such cases, the differential diagnosis often includes a
cystic neoplasm such as a mucinous macrocystic neoplasm.
The key to the correct diagnosis is the hist?ry
of prior episodes of pancreatitis. Follow-up exammations
are also useful, since the intraluminal echoes in a
complex pseudocyst will usually clear over time. In
some cases, aspiration is necessary to make the distinction,
with increased levels of amylase expected in a
pseudocyst and increased levels of carcinoembryonic
antigen in mucinous cystiC neoplasms. Endoscopic retrograde
cholangiopancreatography can also be valuable,
as it may demonstrate changes of pancreatitis that are
not evident sonographically. It may also demonstrate
communication between pseudocysts and the pancreatic
duct in up to 70% of cases.

Front 48

Two transverse views of the thyroid.
1 . What do the arrowheads a t the left side o f the images indicate?
2. Which image would you expect to have the higher frame rate?
3. What can you do to inlprove the frame rate while performing real-time scans?
4. What can you do to improve the resolution while performing real-time scans?

Back 48

F rame Rate and Resol ution
1 . The arrowheads indicate the levels at which the
image is focused.
2. Frame rate should be highest for the second image
because the field of view is smaller, and there is
only one focal zone.
3. Frame rate can be improved by decreasing the
number of focal zones, decreasing the image depth,
decreasing sector width, decreasing line denSity,
and turning off Doppler modes.
4. Resolution can be improved by using a higher
frequency transducer, increasing the number of
focal zones, and increasing line denSity.
Reference
Kremkau FW: Multiple element transducers. Radiographies
1 993; 1 3 : 1 1 63- 1 1 76.
Comment
Each ultrasound image is composed of multiple scan
lines. The time required to create one frame of a realtime
in1age is calculated by multiplying the speed of
sound times the length of the scan lines times the
number of lines per image times two. Multiplying by
two is necessary because the sound has to make a
round trip from the transducer to the target and back.
The longer it takes to generate one frame, the lower the
frame rate . Typical frame rates in diagnostic ultrasound
range from approximately 5 to 40 frames per second.
Increased frame rates can be obtained by decreasing the
length of each scan line (less unage depth) or decreasing
the number of scan lines (less image width or narrower
sector angles).
In many respects, frame rate and ilnage resolution
are competing parameters. As shown in this case, each
scan line can be electronically focused at a certain
depth. To focus at multiple depths requires multiple
pulses for each scan line. In the first image shown in
this case, pulses focused in the near field created the
superficial aspect of the image, which was pasted to
two different images obtained separately with mid- and
far-field focusing. Therefore, the improved resolution
throughout the field of view that comes with multiple
focal zones results U1 a sacrifice in frame rate. It is also
possible to improve resolution by moving the scan lines
closer together. TIllS is called increasu1g line density,
and it also has an uwerse relationship to frame rate.

Front 49

Magnified views of the l iver i n th ree patients. The bottom images are
corresponding grey-scale and color Doppler views from the same
patient. (See color plates.)
1 . What is the differential diagnosis in these three patients with the same abnormality?
2. What factors determine the management of these patients?
3. Would the presence of increased through transmission affect your approach to this lesion?
4. Does the absence of detectable internal flow in the last image affect your differential diagnosis?

Back 49

Hepatic Hemangioma
1. All images show a hyperechoic, homogeneous mass.
Hemangioma is the most likely diagnosis.
Metastasis, hyperechoic hepatocellular cancer, and
nodular fo cal fat are other considerations. Focal
nodular hyperplasia and hepatic adenoma are much
less likely possibilities.
2. Management depends on the patient's risk factors
fo r hepatic malignancy.
3. Hemangiomas occasionally have increased through
transmission, but this can be seen with other solid
lesions as well, so it should not affect your
differential diagnosis significantly.
4. Usually hemangiomas have no detectable flow.
Although some of the other lesions mentioned
previously (hepatocellular cancer, hypervascular
metastasis, fo cal nodular hyperplasia, and hepatic
adenoma) might have detectable flow and may be
hyp ervascular, in some cases it is not possible to
detect flow in these other lesions also. Therefore,
lack of detectable flow may make the diagnosis of
hemangioma more likely, but it does not exclude
the other possibilities.
Reference
Leifer DM, Middleton WD, Teefey SA, et al: Follow-up
of patients at low risk for hepatic malignancy with a
characteristic hemangioma at US. Radiology 2000;
214: 167- 172.
Cross-Reference
Ultraso und: THE REQ UISITES, pp 9- 12.
Comment
Hemangiomas are the most common solid, benign liver
leSion, occurring in approximately 7% of adults. They
are composed of multiple, small, blood-filled spaces that
are separated by fibrous septations and lined by endothelial
cells. They are most common in women. Approximately
10% are multiple. With the exception of cysts,
they are the most common incidental lesion detected
on hepatic sonography.
It is unusual fo r hemangiomas to cause symptoms.
Giant hemangiomas may cause enough mass effe ct to
be symptomatic, and rarely a hemangioma will bleed
enough to cause symptoms. Platelet sequestration and
destruction by hemangiomas has been reported as an
extremely rare cause of thrombocytopenia (called Kasabach-
Merritt syndrome).
The classic sonographic appearance, seen in approximately
60% to 70% of hemangiomas, is a well-marginated,
homogeneous, hyp erechoic mass. Hemangiomas
are usually round (as shown on the first two unages),
S4
but they may have scalloped margins (as shown on the
second two images). The majority are less than 3 cm in
size. Atypical appearances tend to occur ul 1arger lesions
due to fibrosis, thrombosis, and necrosis. A significant
percentage of atypical hemangiomas have a hyperechoic
periphery and a hypoechoic center. This "atypical" appearance
is actually fa irly characteristic of hemangioma
and is seen only rarely in malignant disease. Another
finding occasionally seen in hemangioma is increased
through transmission. A common misconception is that
tlu'o ugh transmission is an important characteristic necessary
to make a confident diagnosis of hemangioma.
This is certainly not true, since the majority of hemangiomas
do not have through transmission, and many other
tumors can have through transmission.
As expected for benign leSions, hemangiomas are
usually stable over time. However, they will occasionally
change in appearance over time. Typically they will
convert fro m hyperechoic to hypoechoic. Rarely, they
will change echogenicity over a matter of minutes or
even seconds. No other hepatic mass has been observed
to have this behavior.
The proper management of a homogeneous, hyperechoic
hepatic mass depends on the patient's clinical
history. In patients at increased risk for hepatic malignancy
(prior history or current evidence of an extrahepatic
malignancy or chronic liver disease), the presumed
sonographic diagnosis of hemangioma should be confirmed
with MR1 or Tc99m-tagged red blood cell scintigraphy.
MRI is superior fo r small lesions (from less than 1
cm to 2 cm in size) and fo r larger lesions adjacent to
the heart or to major hepatic vascular structures. For
patients who are not at ulcreased risk fo r hepatic malignancy,
recommendations fo r the management of suspected
hemangiomas are divergent. Some authorities
have recommended no fu rther evaluation. Others have
reconunended periodic sonographic follow-up. Still others
have recommended confirmation with scintigraphy,
MRI, or CT. We recently analyzed this group of patients
at our own ul stitution and fo und that the risk of malignancy
in this group of patients is extremely low. Out of
more than 200 patients, only one was subsequently
fo und to have a malignant hepatic lesion. Therefore, we
recommend no fu rther evaluation of typical-appearing
hemangiomas provided the patient has no prior history
or current evidence of extrahepatic malignancy or
chronic liver disease.
OccaSionally, noninvasive tests do not establish the
diagnosis of hemangioma, and it is necessary for the
patient to have a biop sy. Biopsy can be performed
safely; however, the needle should pass through normal
parenchyma before entering the hemangioma in order
to achieve some tamponade effect. Fine-needle aspirations
generally obtain only blood and are not suffic ient
to make the diagnosis. Core biopsy needles can obtain
sufficient tissue for diagnosis in the majority of

Front 50

Transverse view of the posterior knee and extended-fie ld-of-view scan of
the posterior knee and calf.
1 . Describe the abnormal findings.
2. Where does this condition occur?
3. How can this lesion be distinguished from other knee cysts?
4. Does this abnormality typically communicate with the joint space?

Back 50

Ru ptu red Baker's Cyst
1 . The transverse view shows a cystic lesion with a
curved beak-like extension heading toward the
deep tissues. The longitudinal view shows the
cystic lesion in the knee and a more complex
appearing fluid collection extending into the calf.
These features are typical of a Baker's cyst that has
ruptured.
2. Baker's cysts occur in the medial aspect of the
posterior knee. The cyst arises from fluid
accumulation in the bursa between the medial head
of the gastrocnemius and the semimembranosus
tendon.
3. The location in the medial posterior knee and the
beaked extension that wraps around the medial
aspect of the medial head of the gastrocnemius
muscle are the best confirmation that a knee cyst is
a Baker's cyst.
4. Baker's cyst typically communicates with the joint.
Reference
Ptasznik R: UltrasOlmd in acute and chronic lmee injury.
Radiol Clin North Am 1999;37:797-830.
Cross-Reference
Musculoskeletal Imaging: THE REQUISITES, pp 28-29.
Conunent
One of the earliest applications of musculoskeletal ultrasound
was in the evaluation of patients with posterior
knee pain and swelling due to a suspected Baker's cyst.
Even prior to the advent of high-resolution linear array
transducers, ultrasound was shown to be effective in
identifying Baker's cysts and in distinguishing them from
other posterior knee masses such as popliteal artery
aneurysms.
Baker's cysts contain fluid distending the bursa between
the medial head of the gastrocnemius and the
semimembranosus tendon. They usually occur as a result
of abnormalities that increase intra-articular fluid.
They can also occur as a result of inflammatory conditions
that affect the synovium of the joint and communicating
bursae.
Baker's cysts may be filled with anechoic fluid and
have thin, imperceptible walls. However, it is not uncommon
to see internal septations; thick, irregular
walls; nodular synovial proliferation; and loose bodies.
The diagnostic feature that is most characteristic is the
neck that extends between the medial gastrocnemius
and the semimembranosus tendon. Tlus usually appears
as a beak when the knee is extended or as a chalU1el
when the knee is slightly flexed. Rupture of a Baker's
cyst should be suspected whenever the inferior aspect
of the cyst converts from a round to a pointed appearance,
or when there is detectable fluid tracking from
the inferior aspect of the cyst.

Front 51

Views of the l iver in two patients.
1 . Is either of the images shown in this case abnormal?
2. Do the intrahepatic ducts run anterior or posterior to the portal veins?
3. What can simulate this abnormality in patients with cirrhosis?
4. Should a 3-mm intrahepatic duct be considered dilated?

Back 51

I ntrahepatic B i l iary Ductal Dil atation
1 . Both images show dilated intrahepatic bile ducts.
The first image shows the dilated bile duct rulllung
adjacent to the portal vein. The second image
shows tortuous, dilated ducts with associated
posterior enhancement.
2. The relationship of intrahepatic bile ducts and
portal veins is variable.
3. Enlarged hepatic arteries can simulate dilated bile
ducts on grey-scale imaging. Tlus is particularly
common in patients with cirrhosis.
4. The upper limit of normal for peripheral
intrahepatic ducts is 2 mm.
Reference
Bressler EL, Rubin ]M, McCracken S: Sonograpblc parallel
challllel sign: A reappraisal. Radiology 1 987;
1 64:343-346.
Cross-Reference
Ultmsound: THE REQUISITES, pp 59-6 l .
Conunent
The intrahepatic bile ducts travel in the portal triads
adjacent to the portal veins and hepatic arteries. Although
the extrahepatic ducts are located anterior to
the portal vein and hepatic artery, the relationship of
the intrahepatic ducts and the vessels is quite variable.
Under normal circumstances, the portal vein is the
largest vessel in the portal triads. A tubular structure
adjacent to the portal vein may be either the hepatic
artery or the bile duct. In the central aspect of the liver,
it is usually possible to trace the arteries back to the
proper hepatic artery and the bile ducts back to the
common hepatic duct. When tlus is not possible , or
when the peripheral aspect of the liver is being imaged,
color Doppler can be used to distinguish the intrahepatic
bile ducts from the intrahepatic arteries.
In the past, any time an intrahepatic duct was seen
as a tubular structure rum1ing parallel to the portal vein,
it was considered abnormal. This was called the parallel
channel sign. However, the normal intrahepatic ducts
can now be seen routinely with ultrasound. Therefore,
current criteria used to diagnose intrahepatic dilatation
are a duct that exceeds 40% of the diameter of the
adjacent portal vein or a peripheral duct that is 3 mm
or greater in diameter. With marked intrahepatic ductal
dilatation, the ducts become tortuous, aSSlUne a stellate
configuration centrally, and are associated with increased
through transmission.

Front 52

Tra nsverse views of the scrotu m i n two patients with the same
a bnormal ity.
1 . Is the location of the testis more typical in the first or in the second image?
2. What is the likely cause of this condition?
3. What would you expect to see at increased gain settings?
4. In what anatomic space is this abnormality located?

Back 52

Hydrocele
1. The testis is usually attached to the posterior aspect
of the scrotal wall, as shown in the first image.
However, this is variable, as shown in the second
unage.
2. Hydroceles of this size are usually idiopathic in
origul.
3. Crystals often develop m chronic hydroceles and
can be seen as low-level reflectors floatulg m the
fluid when the gam is mcreased.
4. Hydrocele fluid is contamed m the scrotal sac
formed by the tunica vaginalis.
Reference
Feld R Middleton WD: Recent advances Ul sonography
of ;he testis and scrotmn. Radiol Clin Nortb Am
1 992;30 : 1033- 1 05 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 446.
Comment
A hydrocele is a collection of increased fluid in the sac
formed by the tunica vaginalis. A small amount of fluid
around the testis is normal and is commonly seen on
sonography. Collections that exceed approximately 1
cm in maximum dimension are less common . Hydroceles
surround the testis over approximately 75%
of their cU'cumference on transverse views and over
approximately 50% on longitudinal views. The remamdel'
of the testis is adherent to the wall of the scrotum,
so that hydrocele fluid cannot flow behuld the entire
testis. Although variable, hydroceles typically collect in
the anterior aspect of the scrotum and displace the
testis posteriorly. An unusual form of a hydrocele occurs
when there is a fluid collection m a focally unobliterated
portion of the processus vagulalis withul the spermatic
cord. Tllis appears as a supratesticular cystic mass and
is called a funiculocele or a hydrocele of the spermatic
cord.
Causes of hydrocele ulc1ude u1fections, torsion of the
testis or one of its appendages, trauma, and testicular
tumors. However, all of these conditions typically cause
relatively small hydroceles. Large, simple-appearmg hydroceles
such as the ones shown in these patients are
usually idiopat1lic.
In patients with large hydroceles, it is usually difficult
to palpate the testis on physical exammation. Therefore,
one of the mlportant roles of sonography is to image
the testis and exclude testicular pathology. When the
testis is displaced posteriorly, it can be difficult to get a
good image of the testis from the typical anterior approach.
Instead, a posterior approach brings the transducer
closer to the testis and allows for a more detailed
view.

Front 53

Long itud inal g rey-scale and power Doppler views of the neck. (See color plates .)
1. Describe the abnormality.
2. What other test is useful in establishing this diagnosis?
3. Are these lesions usually hypervascular?
4. Are these lesions usually benign or malignant?

Back 53

Parathyroid Adenoma
1. An oval-shaped, hypoechoic, hypervascular mass is
located posterior to the thyroid.
2. The other valuable test for localization of a
parathyroid adenoma is a sestamibi scan.
3. Parathyroid adenomas are usually hypervascular.
4. Parathyroid adenomas are benign. Parathyroid
cancer is very rare.
Reference
Shawker TH, Avila NA, Premkumar A, et al: Ultrasound
evaluation of primary hyperparathyroidism. Ultrasound
Q 2000; 1 6:73-87.
Cross-Reference
Ultrasound: THE REQUISITES, pp 452-454.
Comment
The most common cause of primary hyperparathyroidism
is a solitary parathyroid adenoma. Approximately
1 5% of cases are caused by multiple enlarged glands
(usually parathyroid hyperplasia and, less commonly,
multiple adenomas). Parathyroid cancer i s rare and
causes less than 1 % of cases of hyperparathyroidism.
Primary hyperparathyroidism is more common in
women.
Parathyroid adenomas are typically solid but very
hypo echoic lesions. They are usually oval-shaped, with
the long axis m the craniocaudal direction. On color
Doppler unagillg, many adenomas are hypervascular.
The typical location for parathyroid adenomas arisillg
from the superior gland is behuld the mid aspect of the
thyroid. Adenomas arisulg from the u1ferior glands are
typically located close to the i11ferior aspect of the
thyroid or a few centimeters below the thyroid.
Sensitivity of ultrasound for detectulg parathyroid adenomas
is approxiInately 80%, although both lligher
and lower values have been reported. False-negative
examulation results generally arise as a result of a small
adenoma or an adenoma ill an ectopic location, or ill a
patient with a large, multillodular thyroid gland. Falsepositive
results are less of a problem but do occm.
Lymph nodes can be nlisinterpreted as parathyroid adenomas.
A useful clue is that parathyroid adenomas are
essentially always located medial to the carotid arteries.
Lymph nodes can be located in a variety of locations
but are usually located lateral to the carotids. Posteriorly
located thyroid nodules can also simulate parathyroid
adenomas. Usually, there is a bright li11e that separates
a parathyrOid adenoma from the thyroid, while there is
no such IUle between thyroid tissue and thyroid nodules.

Front 54

Magnified transverse views of the pancreatic head.
1 . What are the two important findings on these scans?
2. Where is this abnormality usually located?
3. How good is ultrasound in visualizing this abnormality?
4. What is the treatment of this abnormality?

Back 54

C holedocholithiasis
1 . The most important findings are a dilated bile duct,
best seen on the first image, and a shadowing
echogenic structure in the lumen of the duct on
the second image.
2. Common bile duct stones are usually located in the
distal, intrapancreatic portion of the duct.
3. In the best series, ultrasound has a sensitivity of
75% in identifying common duct stones.
4. ConuTIon duct stones are treated with endoscopic
retrograde cholangiopancreatography (ERCP),
balloon retrieval, and sphincterotomy.
Reference
Middleton WD: The bile ducts. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1 993, pp 1 46- 172.
Cross-Reference
Ultrasound: THE REQUISITES, pp 6 1 -63 .
Comment
Choledocholithiasis is the most common cause of biliary
obstruction. Approximately 85% of cases arise from gallstones
that pass through the cystic duct and into the
common bile duct. In fact, approximately 1 5% of patients
with cholecystitis have choledocholithiasis. Pigmented
stones can form de novo in the bile duct. Usually
tlus is due to bile stasis or superimposed biliary
infection. The majority of common duct stones are located
in the distal, intrapancreatic portion of the duct.
Only 1 0% are seen in the proximal portion of the common
duct.
Ultrasound is frequently the initial imaging test used
in patients with common duct stones. The primary
finding that is usually observed is a dilated duct. TIus
is typically the case in patients with jaundice due to
choledocholithiasis. Unfortunately, a m inority of p atients
with choledocholitluasis have an unobstructed or
an internlittently obstructed duct, so that ductal diameter
is normal. This is often the case in patients with
cholecystitis or biliary colic who have also passed a
stone into the bile duct. Therefore, the sensitivity of
using dilated ducts to predict choledocholitluasis varies
with the patient population being scanned.
Visualization of common duct stones is much more
difficult than visualization of stones in the gallbladder.
When ductal stones are seen, they appear as echogenic
structures in the bile duct lumen. Although acoustic
shadowing is usually present, it is seen less commonly
than with stones in the gallbladder.
In the best of hands, the sensitivity of sonography in
visualizing common duct stones is 70% to 80%. In many
reported series, however, the sensitivity is less than
50%. The primary reason for this low sensitivity is that
60
most common duct stones are located in the most distal
aspect of the duct, and this segment is often not completely
seen on sonograms. Using the gallbladder as a
window, scanning tlu-ough a fluid-filled stomach, and
scanning the patient in an upright position are all techtuques
that can help to improve visualization of the
distal duct.

Front 55

lon g itudinal views of the right upper quadrant in two patients.
1 . List the echogenicity of liver, kidney, spleen, and pancreas from most to least echogenic.
2. What is the most common cause of the abnormalities shown in these images?
3. In the first unage, is the liver or the kidney more likely to be abnormal?
4. Why is the diaphragm so poorly seen U1 the second in1age?

Back 55

Fatty I nfi ltration of the Liver
1 . Pancreas -'? spleen -'? liver -'? kidney.
2 . Fatty infiltration is by far the most common cause
of hepatic hyperechogenicity.
3 . Because fatty infiltration of the liver is so common,
when there is a large discrepancy in the
echogenicity of the liver and the kidney, it is much
more likely that the liver is too echogetuc than that
the kidney is too echolucent.
4. Sound attenuation by the fatty liver linuts
visualization of the deeper structures, including the
diaplu-agm.
References
Mergo PJ, Ros PR, Buetow PC, Buck JL: Diffuse disease
of the liver: Radiologic-pathologic correlation. Radiographies
1 994; 1 4: 1 29 1 - 1 307.
Zweibel W]: Sonographic diagnosis of diffuse liver disease.
Semin US CT MRI 1 995; 1 6:8- 1 6.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 6- 1 8
Comment
Normally the liver and the right kidney are either very
similar in echogenicity or the liver is just slightly more
echogetuc than the kidney. In tlus case, the difference
in echogetucity between the liver and the kidney is
abnormal. In the majority of cases, this is due to fatty
infiltration. A large number of processes can cause fatty
infiltration of the liver, but the most common cause is
obesity. Other common causes include alcohol abuse,
total parenteral nutrition, diabetes, malnutrition, steroid
use, hepatic toxins, and chemotherapy.
In addition to increased echogenicity, the fat-infiltrated
liver appears to have a finer and more compact
parenchymal echo pattern than normal liver. More severe
fatty infiltration also causes sound attenuation, so
that the deeper aspects of the liver are hard to penetrate.
This may manifest as decreased echogetucity of
the deep liver, poor definition of the diaplu-agm, or
poor visualization of the hepatic vessels. These latter
findings are seen in the second image.

Front 56

Pai red longitudinal views of the g a l l bl adder i n one patient and paired
transverse views of the gallbladder in another patient.
1 . In each patient, which unage is more diagnostic for gallstones?
2. What technical parameter causes the difference Ul the itnages of the first patient?
3. What technical parameter causes the difference Ul the images of the second patient?
4. Is there a significant difference between the sonographic appearance of calcified and noncalcified
gallstones?

Back 56

Techn ical Parameters I m portant i n
Producing Sh adowi ng From S mall
G a l lstones
1 . In each patient, the second image is most
diagnostic of gallstones because it shows
shadowing.
2. In the first patient, the focal zone is properly
positioned at the level of the stone in the second
image. In the first image, the focal zone is located
deep to the stone.
3. In the second patient, a higher frequency (8 MHz)
probe has been used in the second unage. A 4 MHz
probe was used Ul the first image.
4. Calcified and noncalcified stones appear the same
on sonography.
Reference
Middleton WD: Right upper quadrant pain. In Bluth
EI, Benson C, Arger P, et al (eds): The Practice of
Ultrasonography. New York, Thieme, 1 999, pp 3 - 1 6.
Cross-Reference
Ultrasound: THE REQUISITES, pp 38-40.
Comment
The sonographic criteria for gallstones include: 1 ) echogerlic
structure in the gallbladder lumen; 2) mobility
demonstrated by movulg the patient UltO different positions;
and 3) posterior acoustic shadowing. Sludge balls
can appear as mobile, echogenic, intralumulal structures,
but they do not shadow. Polyps can appear as
echogenic , i nt raluminal structures, b u t they do not
move and do not shadow. Rarely, gallstones are nonmobile
because they are adherent to the gallbladder wall,
are trapped behind a fold, or are embedded Ul a gallbladder
full of viscous sludge.
Shadowing is related to sound attenuation, which Ul
turn is related to reflection, refraction, scattering, and
absorption of the sound. With gallstones, absorption of
the sound is the key factor in prodUCUlg shadowulg.
Shadowing is related to the size of the stone and is
largely independent to the composition of the stone. In
other words, noncalcilied stones (approximately 85% of
total stones) shadow just as much as calcified stones.
Stones Ul the 3 mm or less size range may not shadow
regardless of their composition.
In attempting to produce shadowulg Ul small stones,
it is important to optilnize scanning technique. Focus
the transducer at the level of the stone so that the beam
profile is mu1imized and the stone blocks as much of the
beam as possible. Also, use as high a probe frequency as
possible because penetration through the stone will be
62
mu1i1nized. Fillally, if there are multiple, small, nonshadOWUlg
stones, change the patient position so that the
stones are aggregated together and therefore act as a
single larger stone.

Front 57

lon g itudinal views of the rig ht and left kid ney.
1 . What abnormality do both of these kidneys demonstrate?
2. What is the specificity of this abnormality?
3. What next test will help the most in establishing the diagnosis?
4. How well does normal renal echogenicity exclude renal dysfunction?

Back 57

Renal Parenchymal Disease
1. Both kidneys demonstrate increased echogenicity.
2. Increased renal echogenicity is relatively specific for
renal parenchymal disease, but it does not predict
the type of parenchymal disease.
3. The only effective way to distinguish the different
types of parenchymal disease is to use clinical
information or to do a biopsy.
4. Normal renal echogenicity does not exclude renal
parenchymal disease.
Reference
Platt JF, Rubin JM, Bowerman RA, Marn CS: The inability
to detect kidney disease on the basis of echogenicity.
A]R Am ] Roentgenol I988; 1 5 1 : 3 1 7-3 1 9 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 05- 1 06.
Comment
Abnormalities of renal echogenicity can be detected by
comparing the kidneys to the liver and the spleen. The
right kidney is usually less echogenic than the liver,
although it can be isoechoic to the liver and still be
normal. If the right kidney is more echogenic than the
liver, then it should be considered abnormal. Since the
spleen is more echogenic than the liver, the left kidney
should be considered abnormal if its echogenicity is
equal to or greater than that of the spleen.
When comparing renal, hepatiC, and splenic echogenicity,
it is important to adjust the distance gain compensation
(DGC) curve so that the hepatic and splenic
echogenicity is uniform throughout. If this is not possible,
then be sure to compare the kidney to regions of
the liver and spleen that are at equivalent depths.
In some patients, it is not possible to directly compare
the kidney to the liver and spleen. Tlus might
occur when the spleen is small, when there is abundant
ascites separating the kidneys from the liver and spleen,
or when the liver and spleen are not normal. In particular,
in the setting of fatty infiltration of the liver, the
kidney may be abnormally echogenic and still appear
hypoechoic compared to the liver. In such cases, the
renal cortex can be compared to the medullary pyramids.
When the cortex is hyperechoic, the pyranuds
often appear unusually hypoechoic, and this can be
used as a soft indicator of renal cortical disease.
Although increased renal echogelucity indicates renal
parenchymal disease, it is extremely nonspecific. Many
different p rocesses produce the same appearanc e .
Therefore, i n a patient with renal dysfunction and echogenic
kidneys, biopsy is frequently performed in order
to determine the nature of the parenchymal disease.

Front 58

lon g itudinal views of the scrotu m i n two patients.
l . Do these patients have anything in common?
2. Is this abnormality likely to be palpable?
3. Is this abnormality commonly or uncommonly seen on ultrasound?
4. What does this lesion contain?

Back 58

S permatocele
1 . Both patients have simple-appearing extratesticular
cysts located above the testis. In the first image, the
cyst is clearly ariSing within the head of the
epididymis . In the second unage, the cyst obscures
the epididymal head.
2. Spermatoceles are palpable unless they are very
small.
3. Spermatoceles are very common.
4. The fluid in a spermatocele contains spermatozoa.
Reference
Feld R, Middleton WD: Recent advances in sonography
of the testis and scrotum. Radiol Clin North Am
1 992;30 : 1 033- 1 05 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 435-437.
Comment
Cysts of the epididynlis are extremely common. With
improvements in resolution that have occurred since
the mid 1 990s, it is actually uncommon not to see a
cyst Ul the epididymis. An epididymal cyst is the most
common cause of a palpable mass in the scrotum. These
cysts are called spermatoceles when they are filled with
spermatozoa. They are called epididymal cysts when
they contain serous fluid . In the majority of cases,
spermatoceles and epididymal cysts both appear as SinlpIe
cysts without internal echoes, so it is not possible
to tell one from the other. Statistically, spermatoceles
are more COlnmon. Spennatoceles most often occur in
the head of the epididynus. They may contaul internal
septations, especially when they become large. It is
uncommon to have symptoms related to a spermatocele,
although they may become a cosmetic problem
when they are large.
The differential diagnosis of a spermatocele is limited.
Hydroceles are usually easily differentiated from
spermatoceles because they surround the testis on all
sides except for the bare area where the testis is anchored
to the scrotal wall. Spermatoceles push the testis
rather than surround the testis. An unusual form of
hydrocele is called a funiculocele. This represents fluid
that accumulates witllin a focally unobliterated portion
of the processus vaguulis Ul the spermatic cord. Like a
spermatocele, a nuuculocele is located superior to the
testis and may displace the testis uueriorly. If a normal
epididymal head is visualized separate from the lesion,
the cyst is very unlikely to be a spermatocele and much
more likely to be a funiculocele.

Front 59

Transverse and longitu d i na l views of the pancreas.
1 . What are the abnormal findings?
2. What are the two most common causes of this disorder?
3. What is the primary role of ultrasound in this disorder?
4. Are most abnormalities in the pancreas hypoechoic or hyperechoic?

Back 59

Acute Pancreatitis
1 . Both images show an enlarged and hypoechoic
pancreas.
2. Gallstones and alcohol abuse are the most common
causes of pancreatitis.
3 . UltrasOlmd is used to look for gallstones or bile
duct obstruction, and to help resolve questions
raised by CT.
4. Most pancreatic pathology is hypoechoic.
Reference
Balthazar EJ, Freeny PC, vanSonnenberg E: Imaging and
intervention in acute pancreatitis. Radiology
1 994; 1 93 : 297-306.
Cross-Reference
Ultt'asound: THE REQUISITES, pp 1 26- 1 29 .
COlrunent
Either gallstones or alcohol abuse causes approximately
75% of cases of acute pancreatitis in the United States.
Other, less common causes include drugs, hyperlipidentia,
ischemia, viral infections, pancreas divisum, and
trauma. Approximately 1 0% of cases are idiopathi c .
Many o f the idiopathic cases may be due t o biliary
sludge. Obstruction of the pancreatic duct is believed
to be responsible for increased intraductal pressure and
release of pancreatic enzymes into the interstitial tissues.
Alcohol causes precipitation of proteins that obstruct
the ducts, and gallstones produce obstruction
when they pass through the bile duct and lodge at the
ampulla. The severity of pancreatitis ranges from the
mildest interstitial (edematous) form, where there is
edema isolated to the pancreas itself, to necrotizing
pancreatitis, where there is extensive necrosis of the
pancreatic parenchyma and adjacent tissues.
The role of sonography in patients with pancreatitis
is primarily to evaluate the biliary tract for the presence
of gallstones as a possible etiology ,md the bile duct for
possible obstruction. Evaluation of the pancreas itself is
certainly possible with ultrasound, but CT, especially
contrast-enhanced CT, is superior in determining the
severity and extent of pancreatitis.
Many patients with pancreatitis have a sonographically
normal prulcreas. When present, the sonograpltic
s igns of pancreatitis include increased size and decreased
echogelticity of the pancreas, ruld slight enlargement
of the pancreatic duct. Echogenicity is somewhat
unreliable, since the base line echogenicity of the pancreas
is variable, and since it is compared to the echogenicity
of the liver, wltich varies depending on the
presence and degree of fatty iniiltration. The detection
of pancreatic enlargement is also rather subjective. To
66
further complicate the matter, the pancreas may be
difficult to visualize owing to an associated ileus (which
causes overlying gas-iilled bowel loops) and pain (wltich
precludes compression of the epigastrium). Therefore,
it is importrult to look other places as well. FortlU1ately,
edema and fluid collections frequently dissect into the
anterior pararenal fascia, which is usually visible sonographically.
In fact, detection of otherwise unexplained
fluid around the kidney should always raise the suspicion
of pancreatitis. Fluid may also dissect around the
splenic hilum and the peripancreatic vessels. Tiny
amounts of fluid may accumulate between the body of
the pancreas and the portosplenic confluence. This is
sometimes referred to as perivascular cloaking.

Front 60

Long itu d i nal views of the g a l l bladder.
1 . What is the differential diagnosis based only on the first image?
2. How does the second image help in establishing the diagnosis?
3. How can follow-up studies help?

Back 60

Tu mefactive S l udge (Sludge ball)
1 . In addition to gallstones, the first unage shows wellformed,
nonshadowing echogenic material. The
differential diagnosis includes sludge, clotted blood,
and neoplasm.
2. The second unage excludes neoplasm because it
documents mobility.
3. In some patients tumefactive sludge does not move.
In such cases it is useful to get follow-up scans
because the sludge usually changes over tinle.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltunore, Williams & Wilkills,
1 993, pp 1 1 6- 1 42 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 40-42.
COlll1llent
In most cases, sludge forms a layer of echogeltic material
along the dependent aspect of the gallbladder lumen.
Occasionally, sludge forms a more mass-like aggregate
referred to as a sludge ball or as tumefactive sludge. As
is true with typical sludge, sludge balls are mobile and
do not cast an acoustic shadow. The lack of shadowulg
helps to distinguish sludge balls from stones, and the
mobility helps to distulguish sludge balls from tumors
or polyps. Internal vascularity can be detected in many
large polyps and polypoid cancers but is not present in
sludge. Therefore, color Doppler can occasionally help
in the differential diagnosis.
In some cases, tumefactive sludge forms in the presence
of bile so viscous that it is Ullpossible to document
mobility. In such cases, a follow-up s can in several
weeks can be useful, SUlce sludge may resolve, regress,
or change in some other way.

Front 61

Lon gitudinal color Doppler views of the left scrotu m . (See color plates) .
1 . What was the patient asked to do when the second color Doppler image was taken?
2 . What is the etiology of tllis condition?
3. What is the significance of this lesion?
4. Are these lesions typically unilateral or bilateral?

Back 61

Varicocele
1 . Flow is augmented and becomes detectable when
the patient performs a Valsalva maneuver.
2 . Incompetent valves in the spermatic vein cause
varicoceles.
3. Varicoceles can potentially contribute to infertility.
When large, they can cause pain.
4. Typically, 85% are unilateral on the left; 10% to 1 5%
are bilateral. Unilateral right varicoceles are rare.
Reference
Feld R, Middleton WD: Recent advances in sonography
of the testis and scrotum. Radiol Clin Nortb Am
1 992;30: 1 033- 1 05 1 .
Cross-Reference
Ultmsound: THE REQUISITES, pp 446-449.
COffilllent
The veins of the pampiniform plexus enter the spermatic
cord and drain into the internal spermatic veins.
The left spermatic vein empties into the left renal vein,
and the right empties into the inferior vena cava. Varicoceles
are dilated veins of the pampiniform plexus. They
are almost always caused by incompetent valves within
the internal spermatic vein. Incompetent valves allow
increased hydrostatic pressure when the patient is upright,
which results in gradual enlargement of the veins.
Varicoceles predominate on the left, because compression
of the left renal vein as it passes between the
superior mesenteric artery and the aorta causes higher
pressure on the left side. In rare instances, varicoceles
can be due to obstruction of the spermatic veins secondary
to processes such as masses, retroperitoneal
fibrosis, or venous tlm10r invasion.
Although controversial, most investigators believe
that even small, subclinical varicoceles may contribute
to abnormal semen analysis results, and that treatment
of varicoceles may improve fertility. Therefore, the diagnosis
of a varicocele is important, especially in the
investigation of male infertility.
Varicoceles appear as an increased size, number, and
tortuosity of the veins around the testis. When small,
they are usually seen most prominently at the superior
or lateral aspect of the testis. Large varicoceles extend
to the posterior and inferior aspect of the scrotum.
Reports indicate that normal peritesticular veins should
be less than 2 or 3 mm in diameter. In my experience,
they seldom exceed 2 nun. On color Doppler scanning,
venous flow in varicoceles is generally too slow to be
detected with the patient at rest. Sometimes, this slow
flow is apparent on grey-scale imaging. With a Valsalva
maneuver, there is augmented retrograde flow in the
varicocele that is readily detectable on color Doppler
68
imaging. This augmented flow usually lasts longer than
one second. In a patient with infertility, if augmented
flow is not seen when the patient is in the supine
pOSition, the patient should perform a Valsalva maneuver
while being sCaJUled in an upright position.

Front 62

Two color Doppler i mages of the same vessel . (See color plates) .
1 . What is the direction of blood flow in the two images?
2. What is the significance of a positive Doppler frequency shift?
3. Would you usually expect it to be easier to determine flow direction at a Doppler angle of 5 degrees
or of 85 degrees?
4. Under what circumstance would your answer to the preceding question be different?

Back 62

Beam Steering and Color Assig nment
1 . Blood flow is from the right to the left.
2 . A positive Doppler frequency shift indicates that
the flow is toward the origin of the Doppler pulse.
3. Flow direction should be easiest to determine at a
Doppler angle closest to 0 degrees aJ1d hardest to
determine at an angle close to 90 degrees.
4. The preceding answer chaJ1ges if there is extensive
Doppler aliasing at the lower Doppler angles.
Reference
Middleton WD: Color Doppler image optimization and
interpretation. Ultrasound Q 1 998; 1 4 : 1 94- 208.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-470.
COlnment
The most basic aspect of color Doppler unage interpretation
is the determination of flow direction. Blood flow
going toward the origin of the Doppler pulse produces
a positive frequency shift, while flow away from the
Doppler pulse p roduces a negative frequency shift .
Once the sign of the Doppler frequency shift i s known,
it is possible to determine which direction blood is
flowing in a given vessel.
A color Doppler scale always indicates what color is
assigned to different frequency shifts. This scale displays
positive shifts on the top and negative shifts on the
bottom. In general , red is assigned to positive shifts and
blue to negative shifts. However, it is conunon to adjust
the color assignment so that arterial flow is displayed in
red even though it is directed away from the Doppler
pulse. When the color assigmnent is inverted, the color
scale displays red on the bottom and blue on the top.
Another method of changu1g the color assignment in a
vessel is to change the direction of the Doppler pulse.
With iU1ear array transducers, this can be done by electronically
steering the beam, as was done in this case.
With phased array sector or curved array probes, the
Doppler pulse can be redirected by repositionll1g or
reangling the probe. When a vessel is curved or tortuous,
different segments may have different color assignments
owing to variation in the dU'ection of blood flow
with respect to the transmitted Doppler pulse.

Front 63

Lon g itud i n a l g rey-scale view and pulsed Doppler waveform of the g roin.
1 . How does the waveform shown in this case differ from the normal triphasic waveform of extremity
arteries?
2. What is the Significance of this type of waveform?
3. How is the abnormality shown here treated?
4. What is the success of this treatment?

Back 63

Post-Catheterization Pseudoa neurysm
1 . The waveform exhibits pandiastolic flow reversal.
The normal triphasic pattern has only a short
period of flow reversal in early diastole.
2. It comes from the neck of a pseudoaneurysm and
reflects flow into the aneurysm during systole and
flow out of the aneurysm during diastole.
3. Treatment is with ultrasound-guided injection of
thrombin or with compression repair.
4. The success rate of treatment with thrombin
injection is 90% and is somewhat less with
compression.
Reference
Paulson EK, Sheafor DH, Nelson RC, et al: Treatment of
iatrogenic femoral arterial pseudoaneurysms: Comparison
of US-guided thrombin injection with compression
repair. Radiology 2000;2 1 5 : 403 -408.
Cross-Reference
Ultrasound: THE REQUISITES, pp 479-48 1 .
Comment
The frequency of post-catheterization pseudoaneurysm
cPA) increased in the 1 990s owing to the increased use
of large-gauge catheters for vascular interventions as
well as to the increased use of anticoagulation during
and after these procedures. PA typically manifests with
swelling and ecchymosis in the first day or two following
the procedure. In tlus setting, a PA basically is a
hematoma that maintains an internal area of extravascular
blood flow via a patent neck that communicates
with the femoral artery. With time, a fibrous capsule
may develop around the PA.
On sonography, a PA appears as a collection of fluid
adjacent to the injured artery. With grey-scale imaging,
it is often possible to see the collection expand during
systole and contract during diastole. Otherwise, it is not
possible to distinguish a PA from a simple hematoma. A
PA may or may not have a significant amount of clotted
blood at the periphery. It is not unconunon to see
several adjacent PAs connected to each other via thin
tracts.
With color Doppler, it is possible to detect flowing
blood in the lumen of a PA. Typically, blood flow into
the PA concentrates along one wall, and flow out of the
PA concentrates along the opposite wall. This produces
the typical swirling, or "yin-yang," appearance, where
one half of the lumen appears red and the other half
appears blue. There are many variations on tlus pattern
depending on the direction of the inflow jet into the
aneurysm lumen. The key point is not the pattern of
luminal flow but simply the presence of flow. Another
frequently described characteristic of PAs is the "to and
fro" pattern of flow in the neck. This refers to systolic
70
flow (into the PA) appearing on one side of the pulsed
Doppler base line and diastolic flow (out of the PA and
back into the artery) appearing on the other side of the
baseline.
Itutial attempts at nonsurgical treatment of PAs concentrated
on ultrasound-guided compression. Although
this approach is reasonably effective, it is time-consuming,
painful for the patient, and fatiguing for the doctor.
Thrombin injection under ultrasound guidance is much
faster, almost painless, and easy for the doctor. Also,
thrombin injection is more successful and, unlike compression,
does not require termination of anticoagulation.

Front 64

Views of the spleen i n two patients.
1 . Describe the abnormality seen in these patients.
2. Is tilis likely to be acute or chronic?
3. Would other tests be valuable in further characterization of tills abnormality?
4. What are the common causes of tilis abnormality?

Back 64

Splenic I nfarction
1. These lesions are peripherally located, hypoechoic,
and wedge-shaped.
2. Tlus is probably fairly acute, since infarcts tend to
become more hyperechoic with age.
3. Contrast enhanced CT may be helpful, since the
wedge shape may be more apparent and other
infarcts may be seen.
4. COllUnon causes of SplelUC infarction include
emboli of cardiac or atherosclerotic origin,
lymphoproliferative disease, arteritis, pancreatitis,
sepsis, and sickle cell anemia.
Reference
Goerg C. Schwerk WB. Splenic infarction: Sonographic
patterns, diagnosis, follow-up, and complications. Radiology
1 990; 1 74 : 803-807.
Cross-Reference
Ult1'asound: THE REQUISITES, pp 1 47- 1 48.
Comment
Infarcts are one of the most common causes of focal
splenic lesions. When they are small, they usually pro- .
duce no clinical symptoms or only minor symptoms.
Therefore, it is not unusual to see them as incidental
findings. Pain, fever, and diaphragmatic irritation can
occur with large infarcts.
Classically, SplelUC infarctions appear as multiple or
solitary wedge-shaped, peripherally located lesions, as
shown in this case. They are usually hypoechoic but
have also been reported as anechoic. They can also
appear as spherical masses that are impossible to distinguish
from neoplastic processes. In most cases, the
clinical history will suggest the correct diagnosis. I n
some patients, imaging with C T may help i n further
characterization. If there is a contraindication to iodinated
contrast, then MRI is an alternative approach.

Front 65

Transverse g rey-scale and color Doppler view of the portal vein (pv) and
inferior vena cava (ivc) .
1 . What type of Doppler signal would you expect from the vessel running between the PV and the IVC?
2. From where does this vessel usually arise?
3. How often is this vessel located in this location?
4. What is the normal course of this vessel?
Views

Back 65

Replaced Right Hepatic Artery
1 . A Doppler waveform would show an arterial signal
with flow toward the liver.
2. Most of the time, an artery running between the PV
and the IVC is an anomalous right hepatic artery
coming from the superior mesenteric artery.
Occasionally, a hepatic artery may arise normally
from the celiac axis and then travel anomalously
behind the PV prior to entering the liver.
3. Replaced or accessory right hepatic arteries occur
in approximately 20% of the population.
4. Normally the hepatic artery runs anterior to the PV
Reference
Lafortune M , Patriquin H: The hepatic artery: Studies
using Doppler sonography. Ultrasound Q 1 999;
1 5( 1 ) :9-26.
Comment
Normally, the celiac axis divides into the splenic artery,
the left gastric artery, and the common hepatic artery.
The first branch of the common hepatic artery is the
gastroduodenal artery. Beyond the gastroduodenal, the
name of the hepatic artery changes to proper hepatic
artery. The proper hepatic artery then divides into the
right and left hepatic artery. Some variation of this
standard anatomy is present in just under half of the
population.
An artery is called a replaced artery if the entire
artery arises from an anomalous source. An artery is
called an accessory artery if one of its portions originates
from its usual origin and another branch arises
from some other vessel. Replaced or accessory right
hepatic arteries arising from the superior mesenteric
artery are present in approximately 20% of patients.
Unlike the normal hepatic artery, they travel behind the
PV and then ascend to the liver in the hepatoduodenal
ligament. After the replaced hepatic artery passes to the
right behind the PV; it then wraps around the right side
of the PV and eventually is located anterior to the PV
and lateral to the common duct. This can produce a
situation where there are three round structures anterior
to the PV on transverse views, with the common
duct placed between the normal left hepatic artery and
the replaced right hepatic artery.

Front 66

Views of the gal lbladder in two patients.
1 . What is unusual about both of these patients?
2 . Is it possible to predict the composition of stones in these patients?
3. Is this a common finding?
4. Under what circumstance does this occur?

Back 66

Floating G a l lstones
1. In both cases, stones are seen layering in the
dependent portion of the gallbladder, but a stone is
also seen floating in the mid cUe of the gallbladder.
2. Under most circumstances, it is not possible to
predict gallstone composition. However, only
cholesterol stones float, so in tilis case prediction is
possible.
3. This is a very lllcommon finding.
4. Gallstones float only when the specific gravity of
the bile is greater than the specific gravity of the
stone.
Reference
Yeh HC, Goodman ], Rabinowitz JG: Floating gallstones
in bile without added contrast material. AIR Am ]
Roentgenol 1 986; 1 46:49-50.
Cross-Reference
Ultrasound: THE REQUISITES, pp 39-4 1 .
Comment
In the age of oral cholecystography, it was not uncommon
to see gallstones floating in the nondependent
portion of the gallbladder. Tllis was because the opacification
of the bile caused by the medication also caused
an increase in the specific gravity of the bile . If the
specific gravity of the stones is less than that of the bile,
then the stones will float.
Today, oral cholecystography is no longer performed,
so it is very lillcommon for the specific gravity of bile
to exceed that of gallstones. One exception is when
there is some degree of vicarious biliary excretion of
iodinated intravenous contrast material. One of the patients
shown in this case had a contrast enhanced CT
prior to the ultrasound.
Regardless of the reason, when stones are seen to
float in the nondependent portion of the gallbladder, it
is safe to say that they are unusually buoyant, and therefore
to predict that they are composed of cholesterol

Front 67

Transverse views of the gallbl adder.
1 . What two conditions are most likely to produce this sonographic appearance?
2 . Does the nature of the shadowing help in favoring one of the two possibilities?
3. What other imaging examination could be used to confirm the diagnosis?
4. How can you exclude a gallbladder full of stones as a possible diagnosis?

Back 67

Porcelain G a l l bl adder
1. The primary considerations are a porcelain
gallbladder and emphysematous cholecystitis.
2 . A clean shadow favors porcelain gallbladder, and a
dirty shadow favors emphysematous cholecystitis.
3. An abdominal radiograph or a cr scan could help to
distinguish gallbladder wall calcification from gas.
4. It would not be possible to see the back wall of the
gallbladder if the lumen were full of stones.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & WiIkillS,
1 993, pp 1 1 6- 142.
Cross Reference
Ultrasound: THE REQUISITES, pp 50- 5 2 .
Comment
A porcelain gallbladder refers to calcification of the
gallbladder wall. This occurs as a result of chronic inflammation
and is almost always associated with gallstones.
Patients with gallbladder wall calcification are at
increased risk of gallbladder cancer. Although the exact
risk is not uniformly agreed upon , most authorities
agree that patients should undergo a prophylactic cholecystectomy
unless there are contraindications to surgery.
The sonographic appearance of porcelain gallbladder
depends on the distribution and thickness of the calcification.
When the calcification is diffuse and thick, the
superficial wall of the gallbladder is seen as a bright,
curvilinear reflector with an associated shadow. Because
of extensive attenuation of the sound pulse, the back
wall is not visible when the calcification is thick. If the
calcification is thin, enough sound may penetrate the
superficial wall in order to image part of, or even the
entire back wall. Such is the case in this patient. Ability
to see the back wall is important because that excludes
a gallbladder full of stones from the differential diagnosis.
The other consideration in this case is emphysematous
cholecystitis. Both conditions can appear as a
bright, curvilinear line with posterior shadowing. In
general, gas appears brighter than calcification, and the
shadowing from gas appears dirtier than shadowing
from calcification. However, in an individual case these
differences may be hard to rely on. Ring-down artifact,
which appears as a bright line trailing deep to the
gas, is only seen with gas and does not occur with
calcification. In addition, if gas is confined to the lumen
of the gallbladder, it is mobile. If there is difficulty
in distinguishing gas from calcification based on the
sonogram, an abdominal radiograph should be obtained.
If it remains unclear after the abdominal radiograph, a
CT scan should be obtained.

Front 68

Long axis views of the rotator cuff in two patients.
1 . What would you expect to see on these patients' shoulder radiographs?
2. What would you expect to see on these patients' MRI?
3. How good is ultrasound at malting this diagnosis?
4. What type of transducer is used to scan the shoulder?

Back 68

Calcific Tendinitis of the Rotator Cuff
1 . Radiographs may show a focal area of soft tissue
calcification in the region of the rotator cuff. The
calcification may be difficult to see if it is projected
over bone on aLI views.
2. MR! would show a signal void on all sequences. For
this reason, calcific tendinitis is often missed on
MR!.
3. Ultrasound is the best way to identify, quantitate,
and localize calcific tendinitis of the rotator cuff.
4. As with other musculoskeletal examinations,
shoulders should be scanned with a linear array
transducer with a center frequency of 7 to 1 2 MHz.
Reference
Middleton WD, Teefey SA, Yamaguchi K: Sonography of
the shoulder. Sel1'lin Musculoskeletal Radiol 1 998;
2 : 2 1 1 -22 l .
Cross Reference
Ultrasound: THE REQUISITES, pp 455-457.
Comment
Patients with chronic rotator cuff tendinitis may develop
areas of calcification within the substance of the cuff.
When the calcification is dense and well profiled, it can
be seen on shoulder radiographs. However, it is much
easier to see with sonography. In fact, sonography is
the most accurate means of identifying, localizing, and
quantifying rotator cuff calcification. In some centers,
ultrasound guidance is used to aspirate soft areas of
calcification. MRI is excellent at detecting most soft
tissue abnormalities in the shoulder, but, as elsewhere
in the body, it is poor at detecting calcification.
The sonographic appearance of calcific tendinitis is
easy to understand. Like other forms of calcium deposition,
calcium in the rotator cuff produces an area of
increased echogenicity and in most cases an associated
acoustic shadow. Extensive spur formation from the
greater or lesser tuberosity rarely simulates calcium in
the rotator cuff. However, with multiple views, it is
usually possible to make this distinction.

Front 69

Views of the g a l l bladder in two patients.
1 . What is the differential diagnosis?
2 . How does color Doppler assist in the differential diagnosis?
3. What else helps in narrowing the differential diagnosis?
4. What is the treatment of this lesion?

Back 69

Ad enomatous Polyps of the G a l l bladder
1 . The differential diagnosis includes polyp,
tumefactive sludge, clotted blood, cancer.
2 . Color Doppler may indicate that the lesion is
vascularized and thus exclude the possibility of
sludge and clotted blood.
3. Demonstration of mobility excludes the diagnosis of
polyp or cancer.
4. Due to the possibility of malignancy, lesions of this
size are usually treated with cholecystectomy.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Wtrasound. Baltimore, Williams & Wilkins,
1 993 , pp 1 1 6- 1 42 .
Cross Reference
Wtrasound: THE REQUISITES, pp 46-48.
COllll1lent
Large polypoid-appearing lesions of the gallbladder may
be true polyps or intraluminal material that simulates
a polyp, such as tumefactive sludge. Sludge can be
distinguished from a true polyp by noting mobility of
the lesion. Clotted blood and pus behave like sludge
and may simulate polyps but are much less common
than sludge.
True gallbladder polyps, regardless of their histology,
are all composed of viable soft tissue. Therefore, they
all have internal blood flow. With current-generation
scanners, it is often possible to detect this blood flow
with color or power Doppler. Demonstration of flow
eliminates sludge or clotted blood from the differential
diagnOSiS. Inability to detect blood flow with Doppler
does not help much with the differential diagnosis because
some polyps may not have enough flow for it to
be detectable.
Polypoid gallbladder neoplasms can arise from any of
the elements of the gallbladder wall. Of the benign
twnors, adenomatous polyps predominate, but leiomyomas,
lipomas, neuromas, and fibromas have all been
reported. Gallbladder cancer may also appear as an
intraluminal polyp, but these lesions are very rarely seen
when they are less than 1 cm in size. In general, the
larger the size of the polyp, the more likely it is to be
malignant. Polyps that are 5 mm or less in size can be
ignored. Polyps between 5 and 10 nun in size can be
followed to ensure stability. It is not clear when the risk
of cancer exceeds the risk of cholecystectomy in patients
with polyps. However, it is probably reasonable
to remove polyps that are larger than 10 mm, unless
there are contraindications to surgery. One should realize,
however, that an 1 1 -mm polyp is much less likely
to be a cancer than is a 30-mm polyp

Front 70

Views of the g a l l bladder in two patients.
1 . Are these lesions typically sessile or pedunculated?
2 . Is a cholecystectomy indicated?
3. Are these lesions usually solitary or multiple?
4. Is this abnormality associated with gallstones?

Back 70

Cho lesterol Polyps of the G a l l bladder
l. Cholesterol polyps are usually pedunculated.
2. These polyps are benign and do not cause
symptoms, so a cholecystectomy is not indicated.
3. Polyps are usually multiple. However, it is not
uncommon to see only the largest polyp on
sonography.
4. There is no association between cholesterol polyps
and gallstones.
Reference
Collett ]A, Allan RB, Chisholm R], et al: Gallbladder
polyps: A prospective study. ] Wtrasound Med
1 998; 1 7: 207-2 1 l .
Cross Reference
Wtrasound: THE REQUISITES, pp 46-48.
COllll1lent
Nonshadowing, nomnobile, intraluminal defects are typical
of gallbladder polyps. Small nonshadowing stones
that are adherent to the gallbladder wall rarely produce
a similar appearance . Tumefactive sludge can also occasionally
be confused with a polyp.
The most conunon type of gallbladder polyp is a
cholesterol polyp. These polyps are not true neoplasms
but rather enlarged papillary fronds filled with lipidladen
macrophages. Cholesterol polyps represent one
form of cholesterolosis of the gallbladder. The more
common form is the planar variety, where there are
smaller but more diffuse accumulations of triglycerides,
cholest

Front 71

longitudinal view of the l iver and longitu dinal view of the testis i n
d ifferent patients.
1 . What artifact is demonstrated in the two ilnages shown in this case?
2. What causes this artifact?
3. Where else is this type of artifact commonly seen?
4. Does this artifact produce lesions of silnilar size and shape?

Back 71

Mirror I mage Artifact
1 . These images demonstrate mirror image artifact.
2. Air in the lung base and air around the scrotum acts
as an acoustic mirror.
3 . Tlus artifact may be seen anywhere there is a large,
smooth gas interface.
4 . Usually lesions created as mirror images are similar
in size and shape to the original lesion. However, if
the mirror is curved, the mirror image may have a
different size and shape.
Reference
Middleton WD: Ultrasound artifacts. In Siegel M], (ed):
Pediatric Sonography, 2nd ed. New York, Raven
Press, 1 994, pp 1 3- 28.
Comment
Acoustic mirrors can be compared to optical nlin'ors.
With optical mirrors, a smooth, flat surface that reflects
a large amount of light causes a visual duplication of
structures. Surfaces that reflect more light (like a silvered
piece of glass) act as better mirrors than surfaces
that reflect less light (like a sheet of metal). Flat surfaces
produce a mirror image that is identical in size and
shape to the original object, but curved surfaces (like
mirrors at the carnival) produce a distorted mirror image.
Since gas reflects almost 100% of the sound that luts
it, gas is the best acoustic nlirror in the body. This
is particularly true where there are large, smooth gas
interfaces-such as in the lung. Therefore, mirror im,
ages are very common on sonograms that include the
interface between lung and adjacent soft tissues.
The base of the right lung serves as a mirror on right
upper quadrant scans and produces a number of wellrecogluzed
mirror images. Although not always appreciated,
the liver itself is duplicated above the diaplu'agm,
and this accounts for the supradiaphragmatic echogenicity
seen on right upper quadrant scans. The diaphragm
is also commonly duplicated, and this becomes apparent
in areas where the diaphragm is tluck enough to be
resolved sonograplucally. Focal hepatic lesions that contrast
markedly with the normal liver parenchyma are
also fi'equently duplicated above the diaphragm. However,
because the diaplu'agm is curved, the mirror unage
may not be an exact reproduction of the actual lesion.
In addition, the nurror image may arise from a lesion
that is not in the plane of the ilnage. This can produce
an apparently isolated supradiaplu-agmatic lesion. The
trachea is another structure with a large, smooth gas
U1terface. It is therefore capable of acting as a nlirror
on scans of the neck.

Front 72

Views of the g a l l bladder in two patients.
1 . Which image is more typical of this condition?
2. Is this abnormality more common in women or in men?
3. What predisposes to this condition?
4. Is this condition more commonly seen in elderly or ill young patients?

Back 72

G a l l bladder Cancer
1 . The second in1age, wluch shows a hypo echoic mass
encasing a gallstone and u1Vading the liver, is most
typical of gallbladder cancer.
2. Gallbladder cancer is more common in women.
3. Gallstones, chronic wall inflammation, and
gallbladder wall calcification predispose to
gallbladder cancer.
4. Gallbladder cancer is a disease of the elderly.
Reference
Rooholamu1i SA, Tehrant NS, Razavi MK, et al: Imaging
of gallbladder carCU10ma. Radiographies 1 994;
1 4: 2 9 1 -306.
Cross-Reference
Ultrasound: THE REQUISITES, pp 45-47.
Comment
Gallbladder cancer is strongly associated with gallstones
and is likely related to clu-onic u1flammation caused by
the stones. It is usually extensive at the tune of diagno,
sis, so the prognosis is very poor. Metastases are com,
monly present in regional lymph nodes, and direct U1Vasion
of the liver is also commo n . S p read to the
peritoneum and direct u1Vasion of adjacent bowel may
also occur. Because of the association with gallstones,
gallbladder cancer is more conunon U1 women than
U1 men.
The most COl1Unon sonograpluc appearance for gallbladder
cancer is a large, soft-tissue mass that is centered
in the gallbladder fossa. In many cases the mass
completely obliterates the gallbladder so that there is
no recognizable normal gallbladder. Because of t h i s
obliteration, i t can be difficult t o deternune the origu1
of the mass. In such cases, identification of engulfed
gallstones is very helpful because their presence makes
it much more likely that the mass arose from the gallbladder.
Gallbladder cancer can also appear as diffuse or focal
wall tluckenu1g. The wall thickening is usuaUy u-regular,
eccentriC, and solid in appearance. It is very unusual
for gallbladder cancer to produce concentric, uniform
thickelung of the gallbladder wall.
The least common form of gallbladder cancer is a
polypoid intraluminal mass. Polypoid cancers are usually
much larger than belugn gallbladder polyps and are
attached to the wall of the gallbladder by a broad base
rather than by a narrow stalk.

Front 73

Pulsed Doppler waveforms o btai ned from the i nternal carotid a rtery.
(See color plates.)
1 . What different parameters are used to grade carotid artery stenosis?
2. How severe is the stenosis shown in the figures in this case?
3. Which waveform and corresponding velocity is more indicative of the severity of this stenosis?
4. Can a severe stenosis ever be associated with a normal velocity?

Back 73

High-Grade Carotid Stenosis
1. Peak systolic velocity, end-diastolic velocity, the
ratio of internal carotid artery (lCA) to common
carotid artery (CCA) peak systolic velocity, and the
ratio of ICA to CCA end-diastolic velocity are used
to grade carotid artery stenosis.
2. This is a greater than 80% diameter stenosis.
3. The second waveform, which shows a velocity of
greater than 400 cmls, is more indicative of the
high-grade stenosis.
4. A very tight stenosis may rarely be associated with
normal velocities if the flow volume has dropped
almost to zero.
Reference
Cardoso T, Middleton WD: Duplex sonography and
color Doppler of carotid artery disease. Semin Interv
Radiol 1 990;7: 1 -8 .
Cross-Reference
Ultmsound: THE REQUISITES, pp 470-474.
Comment
When an ICA stenosis reaches a value of approxin1ately
50% diameter narrowing, velocities increase . The narrowing
can be estimated based on the velocity. The
easiest parameter to use is the peak systolic velocity.
The end-diastolic velOCity is also useful. Both are obtained
at the site of the stenosis or in the region of the
flow jet just slightly beyond the stenosis. As in tlus case,
when the stenosis is long, the peak velocity may be
isolated to a very small segment of the vessel, and it
may not be detected with color Doppler. Tlus can result
in imprecise placement of the sample volume and velocities
that are normal or only minimally elevated. Without
careful sampling all along the course of the stenosis,
the peak velocity may be n1issed.
A theoretical lin1itation of isolated velocity parameters
occurs when base line velocities are lugher or
lower than normal. Low base line velocities may occur
in the setting of decreased cardiac output, or if there is
a second stenosis in the more proximal vessel or in the
aortic valve. In such a situation, even if the velocity at
the stenosis is increased compared with the base line
values, the velocity may still underestimate the stenosis.
High base line velocities may occur in the setting of a
contralateral internal or common carotid artery occlusion
when all of the flow to the head is through a
single carotid artery. In such a case the velocity may
overestimate the degree of stenosis.
To account for differences in base line velOCity, one
can compare the ICA velocity at the stenotic site to the
velocity in a normal segment of the ipsilateral CCA.
DOing this establishes the CCA velocity as a base line
for each individual patient. Unfortunately, any velocity
82
measurement has a moderate amolmt of variability, and
when two measurements are combined in a ratio, the
variability is multiplied. In addition, the CCA velocity
varies along the length of the vessel, resulting in a range
of ICA to CCA ratios for an individual patient. Therefore,
despite the theoretical advantages, there is usually little
additional accuracy gained by using the ICA to CCA ratio.

Front 74

Long itud i n a l views of the carotid a rtery and the jugula r vei n . (See color
plates.)
1 . What different techniques were used to generate these two images?
2. What is the advantage of the technique shown on the left?
3. What is the advantage of the technique shown on the right?
4. Which technique is capable of determining the maximum flow velocity?

Back 74

Comparison of Color Doppler with Power
Doppler
1. The first image is color Doppler, and the second
image is power Doppler.
2. The advantage of color Doppler is its capability to
determine flow direction and its relative lack of
sensitivity to tissue and transducer motion.
3. The advantage of power Doppler is its increased
sensitivity to slow flow and decreased dependance
on the Doppler angle.
4. Neither can determine maximum flow velOCity.
Pulsed Doppler waveforms are required to do tlus.
Reference
Desser TS, ]edrzejewicz T, Haller MI: Color and power
Doppler sonography: Teclmiques, clinical applications,
and trade-offs for image optinuzation. Ultrasound
Q 1 998; 1 4(3) : 1 28- 1 49.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-470.
Comment
Power Doppler encodes the retun1ing Doppler signal
based on the power of the signal rather than on the
frequency sl1ift. TIus is advantageous because there is
less noise contained in the power information and therefore
a better signal-to-noise ratio . TIus allows for higher
gain settings without superimposed noise. Thus, power
Doppler is somewhat more sensitive to low-velOCity
blood flow than is color Doppler. In addition, power
Doppler is less dependent on the Doppler angle and is
therefore slightly better at detecting flow when the
vessel is close to perpendicular to the direction of the
Doppler sound pulse.
The disadvantage of power Doppler is that it is very
sensitive to tissue motion and therefore is prone to
artifacts. In addition, power Doppler gives no directional
information nor velocity information. Although
power Doppler was initially met with great enthUSiasm,
with most modern equipment, its advantages are usually
outweighed by its disadvantages.

Front 75

Transverse views of the a bdominal wall i n two patients.
1 . Where is this lesion located?
2. Why do the two lesions appear different?
3. What is the most common cause for this abnormality?
4. Do these lesions cross the midline?

Back 75

Rectus Sheath Hematoma
1. The lenticular configuration suggests that this lesion
is in the rectus muscle or sheath.
2. They appear different because the hematomas are
of diffe rent ages. The more solid-appearing
hematoma is more acute, and the more complex
but liquefied hematoma is older.
3. Most rectus sheath hematomas are due to
anticoagulation or to severe contraction of the
rectus muscles from coughing, sneezing, defecation,
and other activities.
4. \X'hen they extend below the arcuate line (located
between the umbilicus and the pubis), they can
cross the midline.
Reference
Fakuda T, Sakamoto I, Ko hzaki S, et al: Spontaneous
rectus sheath hematomas: Clinical and radiologic fe atures
. Abdom Imaging 1996; 21:58-61.
Comment
In addition to anticoagulation, rectus sheath hematomas
can also be caused by blunt or penetrating trauma or
severe rectus muscle contraction. The hemorrhage can
be either in the muscle itself or within the rectus sheath,
but it is usually limited to one side by the linea alba.
When large , rectus sheath hematomas may dissect inferior
to the arcuate line, cross the midline, extend into
the prevesicle space, and put significant mass effect on
the bladder.
The sonographic appearance of a rectus sheath hematoma
depends on when it is imaged. Like other hematomas,
rectus hemato mas are echogenic and solid-appearing
in the acute phase. This is due to clotted blood
in the hematoma. Over a matter of days, the clot begins
to lyse, and the hematoma becomes complex, with
cystic and solid components. With more time, the hematoma
becomes progressively liquefactive and appears as
a simple fluid collection. In some cases, a fluid level can
be seen owing to a hematocrit effect.
Occasionally it can be difficult to tell whether a
lesion is in the abdominal wall or within the peritoneal
cavity. One maneuver that can help is to ask the patient
to take deep breaths and observe the movement of the
intraperitoneal contents (bowel and fa t). Usually this
localizes the depth of the parietal peritoneum and helps
to determine whether the lesion is truly superficial to
this level.

Front 76

Two views of the liver.
1 . What type of transducer was used to scan the liver in the first image?
2. What type of transducer was used to scan the liver in the second image?
3. What is the advantage of the first transducer?
4. What is the advantage of the second transducer?

Back 76

Com parison of Phased Array and Curved
Array Transducers
1. The first itnage was obtained with a phased array
transducer that has a frequency range of 4 to 2
MHz.
2. The second image was obtained with a curved array
transducer that has a fre quency range of 5 to 2
MHz.
3. Phased array transducers provide a large field of
view of deeper structures. They are also small and
can be easily used to scan between ribs and in
other areas where acoustic access is limited.
4. Curved array transducers generally provide better
resolution than phased array transducers, especially
in the near field.
Reference
Kremkau FW: Multiple element transducers . Radiographies
1993;13:1163-1176.
Comment
Because of their ease of use, speed, and flexibility, most
manufac turers have concentrated on multielement electronic
array transducers and have abandoned mechanically
driven transducers. The electronic probes consist
of multiple small crystal elements arranged in an array
at the surface of the probe. By adjusting the timing of
activation of the different elements, an ultrasound pulse
can be created that is steered in various directions and
is fo cused at various depths. By changing the geometry
of the probe, different advantages can be obtaitled.
Phased array transducers have a small, flat head and
create a sound pulse from a composite of multiple
pulses generated by all of the elements in the array.
Curved array transducers have a broad, curved head
and activate only a limited number of adjacent crystal
elements to create a sound pulse. Phased arrays steer
the beam electronically by adjusting the timing of activation
of the different elements. Curved arrays steer the
beam based on the shape of the probe. Most manufacturers
identify a probe based on its type, frequency, and
sometimes size. In the images shown in this case, the
phased array is a P4 -2. The curved array is a C5-2.
Phased arrays can also be identified because the sectorshaped
image comes to a poitlted apex, whereas the
image of a curved array has a curved apex that corresponds
to the shape of the probe.

Front 77

longitudina l/coronal view of the left upper quadrant and p u lsed
Doppler waveform . (See color plates.)
1 . What is the normal structure indicated by the cursors?
2. What is the normal relationship between this structure and the spleen?
3. What is the relationship of this structure and the splenic vein?
4. What is the relationship of tllis structure and the left kidney?

Back 77

Normal Relationship of Pan creatic Ta il and
Spleen
1. The cursors are placed on the tail of the pancreas.
2. The tail of the pancreas extends fr om the body of
the pancreas toward the splenic hilum.
3. The pancreatic tail is positioned below the splenic
vein as the splenic vein exits the splenic hilum.
4. The pancreatic tail is usually immediately anterior
to the upper pole of the left kidney.
Reference
Paivansalo M, Suramo I: Ultrasonography of the pancreatic
tail tlu-ough the spleen and tlu·ough the fluidfilled
stomach. Eur I RadioI 1986;6: 113- 115 .
Cross-Reference
Ultr asound: THE REQUISITES, pp 124- 125.
Comment
Visualization of the pancreatic tail is a challenge with
sonography. The challenge arises fro m its location high
and deep in the left upper quadrant. When the standard
anterior approach is used, shadowing from the gasfilled
stomach and from the splenic flexure of the colon
fre quently obscures much, if not all, of the tail. Filling
the stomach with fluid can displace the colon out of
the left upper quadrant and can provide a suitable window
for visualization of the pancreatic tail. However,
results Witll this technique are variable, and in some
patients visualization is actually diminished.
An alternative technique is to scan from a superior
left lateral approach using the spleen as a window. The
tail of the pancreas extends to the splenic hilum and is
usually located immediately anterior to the upper pole
of the kidney. To find it, start with a coronal, transsplenic
view of the left renal upper pole. The transducer
should then be angled anteriorly until the kidney is no
longer in view. The pancreas then appears as a band of
tissue usually oriented directly at the transducer. In the
splenic hilum, the splenic vein is located superior to
the pancreatic tail and can thus serve as another landmark
fo r identifying the tail. Even in situations where
the tail of the pancreas cannot be seen as a discrete
structure, the trans-splenic view often allows visualization
of abnormalities related to the pancreatic tail, such
as pseudocysts and tumors, that could not be seen from
an anterior approach.

Front 78

Views of the l eft u p per q u a d ra nt i n two patients.
1 . Describe the abnormality.
2 . What is the differential diagnosis?
3. Could these lesions be biopsied percutaneously with ultrasound guidance?
4. Would other imaging tests help in the workup of these patients?

Back 78

Focal Splenic lesions
1. Both images show multifocal, solid, hypoechoic
splenic lesions.
2. The differential diagnosis primarily includes
metastasis, lymphoma, sarcoidosis, and abscess.
Infarcts can also produce an appearance similar to
this.
3. In general, it is preferable to avo id the spleen
because it is very vascul ar. In most patients, other
sites exist that can be biopsied with less risk of
bleeding. However, when necessary, splenic lesions
can be biopsied with ultrasoWld guidance. With the
use of fine-needle aspiration (22- to 25·gauge
needles) and cytologic analysis, the risk is very low.
4. CT could help to define a primary tumor or
ly mphadenopathy elsewhere in the chest or
abdomen. With contrast enhancement, it might
help to further characterize the splenic lesions.
Reference
Goerg C, Schwerk \VB , Goerg K: Sonography of fo cal
lesions in the spleen. AIR Am I Roentgenol 1991;
156:949 -9 53.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 144- 145.
Comment
The sonographic appearance of these splenic lesions
indicates that they are not simple cysts, but it is otherwise
relatively nonspecific. In situations such as this, it
is ve ry important to survey the rest of the abdomen fo r
clues to the correct diagnosis. In some situations, either
a primary abdominal tumor or adenopathy may be seen.
If the adenopathy is extensive, then lymphoma and
metastatic disease are the most likely possibilities. The
first patient had extensive adenopathy, and subsequent
biopsies showed lymphoma. If minimal adenopathy is
seen, sarcoidosis should also be considered. If a primary
tumor is identified elsewhere in the abdomen, then
metastatic disease almost certainly explains the splenic
lesions. In addition, clinical history will usually point in
one direction or the other. The second patient had a
history of lung cancer, and the splenic lesions were
metastases. With the proper clinical hiStory, splenic abscesses
and infarcts should also be considered. If no
other abnormalities are seen sonographically and the
clinical history is not helpful, then CT should be considered
fo r fu rther evaluat ion.

Front 79

I mages of the scrotum in a patient with right scrotal pai n . The two
images of the right testis shown h e re were taken approxi mately 3
m i n utes apart. (See color plates.)
1 . Describe the abnormalities .
2 . What congenital anomaly i s this patient likely t o have?
3. Is it likely that this patient has been symptomatic for less than 24 hours?
4. Explain the difference in appearance of the right testis in the lower left unage compared with the
lower right image .

Back 79

Testicular Torsion
1. The grey-scale view shows testes that are symmetric
in echogenicity and normal in appearance. The
power Doppler view of the left testis shows normal
distribution of flow in multiple intratesticular
vessels. The first power Doppler view of the right
testis shows no detectable blood flow. The second
power Doppler view shows normal intratesticular
flow. The fu'st three views are typical of acute right
testicular torsion. The lower right image was taken
after manual detorsion.
2. The congenital anomaly that predisposes to
testicular torsion is a "bell clapper" deformity.
3. The grey-scale appearance of the right testis is
normal. This is very good evidence that the testis is
still viable. Therefore, it is very likely that the
patient has been symptomatic for less than 24
hours.
4. The patient was manually detorsed between the
first and second power Doppler views of the right
testis. The repeat view of the testis confirmed the
success of the maneuver.
References
Cannon ML, Finger MJ, Bulas DI: Case Report: Manual
testicular detorsion aided by color Doppler ultrasonography.
] Ultrasound Med 1 995 ; 1 4 :407-409.
Middleton WD, Siegel BA, Melson GL, et al: Prospective
comparison of color Doppler ultrasonography and
testicular scintigraphy in the evaluation of the acute
scrotum. Radiology 1 990; 1 77: 1 77- 1 8 l .
Middleton WD, Middleton MA , Dierks M , e t al: Sonographic
prediction of viability in testicular torsion. ]
Ultrasound Med 1 997; 1 6 : 23-27.
Cross-Reference
Ultrasound: THE REQUISITES, pp 443-446.
Comment
Normally, the testis is anchored to the wall of the scrotum
by a broad posterior attachment. This prevents the
testis from significant degrees of rotation. The "bell
clapper" deformity is a congenital anomaly in which
tItis normal attachment is absent, so that the testis is
suspended in the scrotal sac via its vascular pedicle, like
a clapper in a bell. Patients with a bell clapper deformity
are at significantly increased risk for torsion. It is believed
that forceful contraction of the cremasteric muscles
results in elevation and rotation of the testis and
can be the precipitating event in testicular torsion.
Testicular torsion is a condition that most often affects
boys in the peripubertal period or men during the
88
young adult years. Patients often have previous episodes
of torsion that spontaneously detorse before they arrive
at their doctor's office or the emergency room with an
episode of persistent torsion. Typical symptoms include
pain and swelling of the scrotum. The pain may radiate
into the groin and lower abdomen and is often associated
with nausea and vomiting. On physical examination
there is often marked tenderness, and the testis may be
oriented in a transverse lie.
With prompt diagnosis and surgical detorsion, there
is a good chance that the testis can be salvaged . In fact,
if treated within 6 hours of onset, the majority of testes
will maintain their viability. If surgery is delayed beyond
24 hours, ischemia causes permanent necrosis of the
testis in the large majority of cases. Between 6 and
24 hours after onset, the chance of testicular salvage
progressively diminishes.
The diagnosis of torsion is quite difficult to make
based on grey-scale imaging alone. In some patients, the
twisted cord can be seen as a heterogeneous mass
superior to the testis. This is called the torsion knot.
Unfortunately, it is possible to confuse the torsion knot
with an enlarged epididymal head. In the early stages of
torsion, the grey-scale appearance of the testis is normal.
In fact, in the setting of torsion, it is possible to
predict that the testis is still viable if it has a normal
homogeneous echogenicity on grey-scale. On the other
hand, if the testis appears heterogeneous or hypo echoic
on grey-scale, then it is almost certainly nonviable. In
addition to the changes in the testis, torsion also is
frequently associated with a small reactive hydrocele
and thickening of the scrotal skin.
The sonographic diagnosis of testicular torsion depends
on detecting absent or, in some cases, diminished
blood flow to the affected testis with color Doppler.
It is important not to mistake color noise with true
intrat esticular blood flow. Color noise appears as very
small, randomly positioned spots of red and blue color
assignment that have no pulsed Doppler signal. True
vessels appear as larger, better-formed areas of color
assignment that can usually be elongated by various
degrees of transducer rotation. In addition, true vessels
should have a detectable pulsed Doppler signal. With
prolonged torsion, an inflammatory reaction develops
in the scrotal wall, and hyperemia can be detected in
the tissues around the testis.

Front 80

Pulsed Doppler waveforms of the left vertebral a rtery. Please n ote that
both waveforms a re i nverted, with negative frequency sh ifts displayed
a bove the base line.
1 . What i s the cause o f this abnormality?
2. What was done to cause the difference in the two waveforms?
3. Is color Doppler alone adequate to make the diagnosis?
4. Is this abnormality more common on the right or on the left?
Tra nsverse

Back 80

Subcl avia n Steal
1. Tltis abnormality is caused by stenosis of the
subclavian artery prior to the origin of the vertebral
artery.
2 . The first waveform was obtained at rest when there
was a partial steal and retrograde flow only during
peak systole. The second itnage was obtained after
left arm exercise when there was complete steal
and retrograde flow throughout the cardiac cycle.
3. A vertebral vein can be confused with an artery on
color Doppler. Pulsed Doppler waveforms are
needed to show that flow is arterial and not
venous.
4. Subclavian steal is more common on the left.
Reference
Kliewer MA, Hertzberg BS, Kim DH, et al: Vertebral
artery Doppler waveform changes indicating subclavian
steal physiology. A]R Am ] Roentgenol
2000; 174:8 1 5-819.
Cross-Reference
Ultrasound: THE REQUISITES, pp 477-478.
Comment
The left subclavian artery arises in the superior mediastinum
and is difficult to visualize with ultrasound. Therefore,
abnormalities at its origin are typically diagnosed
based on secondary criteria. Since the left vertebral
artery arises from the left subclavian artery, the vertebral
artery can potentially provide collateral flow to the
arm when the subclavian artery is stenosed or occluded
at its origin. When tltis occurs, flow itl the left vertebral
artery is at least partially directed toward the subclavian
artery in a retrograde direction. Sitlce the retrograde
flow is being stolen from the internal carotid arteries
and the right vertebral artery by crossover at the circle
of Willis and the basilar artery, this is referred to as the
subclavian steal phenomenon.
In most instances, the diagnosis is readily made by
notitlg that flow in the left vertebral artery is going
down toward the arm instead of up toward the head.
When the subclavian artery is totally occluded, it makes
sense that there is no way to establish effective antegrade
vertebral flow, so all the flow that is seen itl the
vertebral artery is retrograde. In actuality, elastic recoil
of the upper extremity arteries may result in some
backflow from the arm and into the vertebral artery.
Tltis may be detected as a short phase of minimal antegrade
diastolic vertebral flow despite the presence of
complete subclavian artery occlusion.
When the subclavian artery is patent but stenosed, it
is possible to have significant components of antegrade
90
flow in the vertebral artery. Since the arm is a highresistance
vascular bed, diastolic flow to the arm is
ordinarily litruted. Therefore, diastolic flow may proceed
up the vertebral artery in an antegrade fashion, while
systolic flow itl the vertebral is reversed and sUpplyitlg
the arm. With less amounts of steal, ante grade systolic
flow in the vertebral artery may be only partially affected.
This can produce a dip i n the systolic peak
without resulting in actual flow reversal. Exercisitlg the
arm accentuates changes in the vertebral artery waveform
and makes the diagnosis more certain.

Front 81

Tra nsverse views of the second and third web space of the toes.
1. From what anatomic structure do these lesions arise?
2. What is the most common location of these lesions?
3. Are these lesions more common in men or in women?
4. Are they benign or malignant?

Back 81

Morton's Neu roma
l. Morton'S neuromas arise from the plantar branch of
the digital nerves.
2. They are most often located itl the second and third
web spaces of the foot at the level of the
metacarpal heads.
3. They are more common in women.
4. They are benign.
Reference
Quinn TJ, Jacobson JA, Craig JG, van Holsbeeck MT:
Sonography of Morton's neuromas. AJR A m ] RoentgenoI
2000 ; 1 74 : 1 72 3 - 1 728.
Cross-Reference
Musculoskeletal Radiology: THE REQUISITES, P 455.
Comment
Morton's neuromas are benign masses of the plantar
digital nerves of the foot. They are composed of perineural
fibrosis and are likely due to repetitive trauma.
The strong female predomitlance (80% occur in women)
suggests a relationship with h igh-heeled s h o e s . The
common symptoms are pain and paresthesias with walking
and marked tenderness to direct palpation.
The interdigital nerves course itl the space between
the metatarsal heads. Under normal conditions, they are
too small to be seen sonographically. Neuromas, on the
other hand, can be seen with a reported sensitivity of
approximately 95%. They appear as hypoechoic masses
located in the interspaces of the toes, usually at or just
proxitnal to the metatarsal heads. They may be associated
with slight itlCreased through translrussion and occasionally
are seen connecting to a swollen digital
nerve . They occur most commonly i n the third interspace
and next most commonly in the second interspace.
They may be multiple in approximately 25% of
patients and bilateral in approxitnately 1 0% of patients

Front 82

Views of the liver i n two patients.
1 . What are potential causes of shadowing in the liver?
2 . Is the shadowing in the first case clean or dirty?
3. A liver tumor with calcification is most likely to be what?
4. Are calcifications frequently seen in focal nodular hyperplasia (FNH)?

Back 82

Partia l ly Calcified liver Metastases
1. Shadowing in the liver is most often due to
calcification, air, stones, and fat-containing lesions.
2. The shadowi.ng in the first unage is clean. TI1is
makes air an unlikely cause.
3. Metastases are the most common cause of a
calcified liver tumor.
4. Focal nodular hyperplasia only rarely has
calcification.
Reference
Stoupis C, Taylor HM, Paley MR, et al: The rocky liver:
Radiologic-pathologic correlation of calcified hepatic
masses. Radiographies 1 998; 1 8 :675-68 5 .
Cross Reference
Ultrasound: THE REQUISITES, pp 7-9.
Comment
Hepatic calcifications typically occur in inflammatory
and neoplastic lesions . Inflammatory causes include
granulomatous diseases, such as histoplasmosis and tuberculosis
(small punctate calcifications) and echinococcus
(peripheral curvilinear calcifications), or healed pyogel1ic
or amebic abscesses (coarse calcification).
The most common cause of a calcified l iver tumor is
metastatic disease. Almost any metastatic tumor can
potentially calcify, particularly during treatment. However,
colorectal carcinoma is the most common primary
to produce calcified liver metastases. Others that are
also common are ovarian carcinoma, gastric carcinoma,
and renal cell carcinoma. It is very uncommon for hemangioma,
hepatocellular carCinoma, adenoma, or focal
nodular hyperplasia to contain calcification. Fibrolamellar
hepatocellular carcinoma more commonly contains
calcification U1 the central scar.
On sonography, calcification is hyperechoic and is
usually associated with shadowing. Gas is also hyperechoic
and usually associated with shadowing. Typically,
the shadow seen with gas contains medium- or lowlevel
echoes and has fuzzy borders. This is referred to as
dirty shadowing. The shadow associated with calcium
contains fewer echoes and has sharper borders and is
referred to as clean shadowing. Overlap exists between
shadowing from calcification and from gas, and it is
not always possible to distinguish between the two
sonograpl1ically. When in doubt, radiographs or CT can
help.
Fat attenuates sound more than normal liver parenchyma
and can occasionally produce faint shadowing.
This is sometimes seen in fat-containing tumors or in
focal fatty infiltration.

Front 83

Views of renal transp la nts i n two patients.
1 . What is the abnormal finding?
2. What is the differential diagnosis?
3. How good is ultrasound at diagnosing transplant rejection?
4. Where do posttransplant urinomas usually occur?

Back 83

Rena l Transplant Lym phocele
1 . Both in1ages show a fluid collection adjacent to the
renal transplant.
2 . The differential diagnosis u1cludes lymphocele,
hematoma, seroma, urinoma, and abscess.
3. Like all other itnaging tests, ultrasound is not good
enough at diagnosing rejection to guide patient
management. That is why biopsies are still
necessary.
4. The leak usually occurs at the anastomosis of the
ureter to the bladder. Therefore, the fluid collection
usually is between the lower pole of the transplant
and the bladder.
Reference
Brown ED, Chen MYM, Wolfman NT, et al: Complications
of renal transplantation: Evaluation with US and
radionuclide itnaging. Radiographies 2000;20:607-
622.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 1 6- 1 1 8.
Comment
Peritransplant fluid collections are common following
renal transplantation. In the in1mediate posttransplant
period, hematomas are very common. They typically
appear as complex collections adjacent to the transplant.
Lymphoceles usually occur 1 to 2 months following
transplant and are present in up to 1 5% of patients.
They occur because of disruption of the renal lymphatics.
Both hematomas and lymphoceles are usually
asymptomatic. They may produce symptoms when they
become large enough to compress the ureter or the
renal parenchyma. The latter problem is particularly an
issue with subcapsular hematomas. Urillomas are much
less common and usually occur at the ureteroveside
anastomosis. They can also occur at other sites of the
collecting system owing to ischemia. Abscesses can be
a primary abnormality, or they can occur due to infection
of another preexisting fluid collection.
The sonograpl1ic appearances of these various fluid
collections overlap, so that it is usually necessary to rely
on the clinical l1istory, laboratory studies, and other
imaging tests, such as radionuclide renography, to distinguish
one from the other. In many instances, ultrasound
guided aspiration is required to make a final diagnosis.

Front 84

Tra nsverse color Doppler view of the hepatic vei n s and long itud i n a l view
of the internal mammary a rtery. (See color plates.)
1 . What is unusual about both of these images?
2 . Is this artifact more common on grey-scale linages or on color Doppler images?
3. Where else is this type of Doppler artifact commonly seen?
4 . How can pulsed Doppler help in confirming this artifact?

Back 84

Doppler M i rror I mage Artifact
1 . The first image shows what appears to be a vessel
above the diaphragm, and the second shows a
vessel deep to the internal mammary artery.
2 . Mirror image artifacts are more common on color
Doppler scans than on grey-scale scans.
3. Doppler mirror images can be seen anywhere that
vessels course over the surface of the lung or other
smooth gas interfaces. They are also seen deep to
the common carotid artery and next to large,
smooth, strong reflectors such as bone.
4. Pulsed Doppler can help by confirming that the
signal arising from the artifact is similar to the
signal in the real vessel .
Reference
Middleton WD: Ultrasound artifacts. In Siegel MJ (ed):
Pediatric Sonography, 2nd ed. New York, Raven
Press, 1 994.
Comment
Because color Doppler creates images with marked contrast
between vascular structures and soft tissues (Le.,
color vs. grey scale), mirror image artifacts are partiClllady
common on color Doppler scans. As with greyscale
imaging, color Doppler mirror images occur most
frequently around the lung. However, the increased contrast
also allows weaker acoustic interfaces to act as
mirrors for color Doppler. For instance, bone can reflect
enough sound to produce color Doppler mirror images.
In fact, the back wall of the normal common carotid
artery can act as a mirror and produce artifactual Doppler
signals deep to these vessels. The artifactual arterial
signal deep to the common carotid artery is referred to
as the carotid ghost, and it can be detected on both
color Doppler images and pulsed Doppler waveforms.
In some cases the etiology of the artifactual Doppler
signal can be quite confusing. One helpful technique is
to compare the Doppler waveform of the true vessel
with the waveform of the mirror image. Since the art ifactual
signal is generated by blood flow in the real
vessel (but is sinlply inappropriately localized), it should
have the same size and shape as the signal from the
true vessel. On the other hand, the intensity of the
waveforms may differ. The Doppler signal from the true
vessel arises from the strong, original sound pulse and
appears as a strong signal. The artifactual signal arises
from a sound pulse after it has reflected off the mirror.
If 1 00% of the sound is reflected (as with a gas interface),
then the mirror image signal will be almost as
strong as the original signal. If some of the sound is
transmitted through the mirror and only a portion of it
is reflected, then the mirror image signal will be much
94
weaker than the original signal. To decrease mirror
itnage artifacts both on grey-scale and Doppler images,
the power output and gain settings should be decreased.
This produces a sound pulse that is too weak to reflect
off the mirror and travel back to the transducer.

Front 85

Lon gitudinal g rey-scale image and color Doppler i mage of the posterior
ti bial tendon. (See color plates .)
1 . What are the abnormal findings?
2 . What is the most common cause of this condition?
3. Does the tendon appear intact?
4. Would you expect to see fluid in the tendon sheath?

Back 85

Ten osynovitis
1 . The inlages show thickenitlg and increased
vascularity of the tendon sheath around the tendon.
2. Tenosynovitis has many causes, but the most
common is repetitive micro trauma from overuse.
3. The fibers of the tendon are well seen, and there
are no defects identified. There is no evidence of
tendon tear.
4. Usually tenosynovitis is associated with a tendon
sheath effusion. Other itnages from this patient did
show an effusion.
Reference
Martitloli C, Bianchi S, Derchi LE: Tendon and nerve
sonography. Radiol Clin North Am 1 999;37:69 1 -7 1 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 455-456.
Comment
Sonography is particularly useful in evaluating disorders
of the tendons. Tenosynovitis refers to inflammation of
the tendon sheath and can be due to multiple etiologies.
These include pritnary inflan1111atory processes (rheumatoid
arthritis and other synovial-based arthritides), infection
(either from penetratitlg trauma or blood borne),
crystal-itlduced (gout), trauma (usually repetitive microtrauma),
amyloidosis (chronic hemodialysis), or foreign
bodies. Complications include tendon involvement and
rupture, cellulitiS, compressive neuropathies, abscess
formation, and osteomyelitis.
Tenosynovitis can be diagnosed so no graphically
when there is fluid distending the tendon sheath and/
or thickening of the tendon sheath. The fluid is usually
anechOiC, although complicated tenosynovitis (infectious
or hemorrhagic) may have fluid with low-level
echoes. Tendon sheath thickening may be diffuse and
smooth or eccentric and nodular. With active inflammation,
there is usually a detectable hypervascularity on
color and power Doppler. In most cases, it is possible
to determine the cause of the tenosynovitis based on
the clinical history and associated laboratory finditlgs.
When necessary, ultrasOlmd guided aspiration and biopsy
can also be performed to establish the diagnosis.

Front 86

Transverse and longitud i n a l views of the thyroid i n two patients.
1 . What is the most important finding in the itnages shown here?
2. What is the echogenicity of most thyroid cancers?
3. What is the echogenicity of most benign thyroid lesions?
4. How often is thyroid cancer multifocal?

Back 86

Papilla ry Thyroid Cancer
1. Microcalcifications in a focal, solid, hypoechoic
nodule are the most important finding here.
2. Most cancers are hypoechoic.
3. Echogenicity of benign nodules is variable.
4. Papillary cancer is multifocal in 20% of cases.
Reference
Ahuja AT, Metreweli C: Ultrasound of thyroid nodules.
Ultrasound Q 2000; 1 6: 1 1 1 - 1 2 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 448-4 5 2 .
Conunent
Papillary cancer is the most common thyroid maLignancy.
It tends to occur in younger patients and is more
common in women. As seen in this case, psammoma
bodies (microcalcifications) are conunon. The prognosis
is excellent, even when there are local lymph node
metastases in the neck. Patients typically present with a
painless palpable mass in the thyroid. It is not uncommon
for these patients to present with palpable lymph
node metastases and a nonpalpable tumor in the thyroid.
Mortality at 20 years is approximately 5%. Papillary
cancer often contains some follicular elements and is
then referred to as mixed papillary/follicular or follicular
variant. Mixed cancers behave like pure papillary cancers.
Follicular cancers account for approximately 1 0% of
all thyroid malignancies. They may be minimally invasive
or widely invasive. They metastasize via the hematogenous
route rather than via the lymphatics. Conunon
sites of metastases are lung, bone, liver, and brain. Mortality
at 20 to 30 years is approximately 25%.
Medullary cancer accounts for 5% of thyroid cancers.
These cancers arise from the parafollicular cells and
frequently secrete calcitonin. Approximately 2 0% of
these tumors are seen in patients with multiple endocrine
neoplaSia, type II (MEN-II) syndrome. The prognosis
is slightly worse than for follicular cancer.
Thyroid lymphoma represents less than 5% of thyroid
malignancies and can occur as either a manifestation of
generalized lymphoma or as a primary abnormality. It is
usually of the non-Hodgkin's variety. Women are affected
more than men, and it tends to occur in the
elderly. It generally manifests as a rapidly growing mass.
On sonography, it is usually a large, hypoechoic mass
that infiltrates much, if not all, of the thyroid.
Anaplastic cancer is the least common of the thyroid
cancers. It occurs primarily in elderly patients. It is an
extremely aggressive tumor, with a 5-year survival of
only 5%. These tumors are locally invasive of the adja-
96
cent muscles, vessels, and nerves and are often not
resectable at the tin1e of diagnosis.
Distinguishing benign from malignant thyroid nodules
is not possible with sonography. However, certain
appearances should raise the suspicion for a malignancy.
The most troublesome finding is microcalcifications.
These typically appear as tiny, nonshadowing reflectors
within the nodule. They are most often associated with
papillary cancer but can also be seen with medullary
cancer. Nodules that are entirely solid and hypoechoic
are also more worrisome for cancer. If enlarged lymph
nodes are seen in the neck, especially if they contain
microcalcifications or areas of cystic degeneration, the
chance of malignancy increases greatly.

Front 87

Transverse g rey-scale and power Doppler views of the g ro i n .
1 . What i s the most likely etiology for the lesion shown it1 this case?
2. Can ultrasound distinguish between a solid lesion and a complex cystic lesion?
3. Could this be due to a neoplastic process?
4. Could this be due to an itlfl.ammatory process?

Back 87

I nguinal Adenopathy
1 . Adenopathy.
2 . There can be overlap in the grey-scale appearance
of solid and complex cystic lesions. However, the
vascularity shown on power Doppler would not be
seen in a cystiC lesion.
3. TillS could represent malignant lymphadenopathy.
4 . TillS could also represent reactive
lymphadenopathy.
Reference
Bruneton ]N, Rubaltelli L, Solbiati L: Lymph nodes. In
Solbiati L, Rizzatto G (eds): Ultmsound of Superficial
Structures. Edinburgh, Churchill Livingstone, 1 995,
pp 279-302.
Comment
The differential diagnOSis of a mass in the groin includes
primarily hernia, enlarged lymph nodes, abscess, hematoma,
and pseudoaneurysms. In most patients, the clinical
history will point you in the right direction.
The images supplied show two adjacent hypoechoic
masses with relatively intense hypervascularity. The vessels
fan out into the periphery of the mass from a single
site along the deep aspect of the mass. TillS pattern is
typical of a lymph node. Inflanunatory conditions with
reactive lymphadenopathy can produce tlllS degree of
hypervascularity with a normal branching pattern, and,
if the history were appropriate, that would be a consideration
in tillS case. Neoplastic adenopathy can also
produce hypervascularity. In metastatic disease, the normal
vascular branching pattern is often disturbed and
chaotic-appearing, and vessels are often predon1inantly
peripheral. In lymphoma, the normal pattern is typically
maintained. The diagnOSis in this case was lymphoma,
emphasizing that active lymphoma can be very vascular.

Front 88

Transverse views of the pancreatic h ead i n two patients.
1 . What are the most common causes for focal areas of decreased pancreatic echogenicity?
2. What is the histologic explanation for this finding?
3. How can this condition be distinguished from the other possibilities?
4. How often is this seen?

Back 88

Normal Va riant Pancreatic Head
1 . Pancreatitis and pancreatic tumors are p robably the
most widely described causes of decreased
pancreatic echogenicity. However, the normal
variant shown in these images is also a common
cause.
2. Decreased fat in the posterior pancreatic head and
lU1cinate process causes the difference in
echogenicity.
3 . The normal variant has a straight anterior border,
produces no mass effect, and does not cause
pancreatic or biliary ductal obstruction.
4. This is seen in 50% of autopsy specin1ens but in
much less than 50% of cases seen in clinical
practice.
References
Atri M, Nazarnia S, Mehio A, et al: Hypoechoic embryologic
ventral aspect of the head and uncinate process
of the pancreas: In vitro correlation of US with histopathologic
findings. Radiology 1 994; 1 90:441 -444.
Donald ]], Shorvon P], Lees WR: Hypoechoic area within
the head of the pancreas-A normal variant. Clin RadioI
1 990;4 1 :337.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 24- 1 2 5 .
Comment
The pancreas originates as two embryologic anlagen.
The dorsal bud ultimately rotates into an anterior location
and gives rise to the anterior aspect of the pancreatic
head and to the pancreatic body and tail. The
ventral bud rotates to a posterior location and gives rise
to the posterior aspect of the pancreatic head and the
uncinate process. Normally, the echogenicity of the pancreas
is homogeneous throughout. However, in some
patients an area of decreased echogenicity is seen in
the portion of the pancreas corresponding in location to
the ventral anlage. Studies have shown that this normal
variant is due to decreased fatty deposition in the hypoechoic
region.
This normal variant can be seen in approximately
20% of patients. It is seen more commonly in older
patients and in patients in whom it is possible to get
an unusually good look at the pancreatic head. Unlike
pancreatic cancer and focal pancreatitis, this normal
variant is well demarcated from the more echogenic
pancreas, and the interface between the two areas is
relatively straight. There is no mass effect on adjacent
structures, and there is no obstruction of either the
common bile duct or the pancreatic duct

Front 89

Views of the testis in two patients.
1 . Is this lesion typically palpable?
2. How good is ultrasound at detecting this abnormality?
3. What is the typical size of this lesion?
4. How do these patients usually present?

Back 89

Tu n ica Al buginea Cyst
1 . Unlike intratesticular cysts, tunica albuginea cysts
are usually very [lrm and easily palpated.
2. Usually ultrasound is very good at detecting these
cysts. However, the area of the palpable mass must
be carefully scanned to avoid overlooking tlU1ica
albuginea cysts .
3 . Cysts in the tunica albuginea are usually very small.
4. Patients usually present with a painless mass on
physical examination.
Reference
Martinez-Berganza MT, Sarria L, Cozcolluela R: Cysts of
the tunica albuginea: Sonographic appearance. A]R
Am ] RoentgenoI 1 998 ; 170 : 183- 185.
Cross-Reference
Ultrasound: THE REQUISITES, pp 435-439.
Comment
Cysts of the tunica albuginea are entities distinct from
intratesticular cysts. Typically they are very firm on
physical examination and often are first recognized by
the patient himself. Since they arise from the tunica
albuginea, they are always located at the periphery of
the testis. Although they occur in a range of sizes, they
are most often less than 5 111m in diameter. A fibrous
plaque of the tunica albuginea is another lesion that can
present as a firm, palpable nodule in the periphery of
the testis. This lesion is usually the result of postinflammatory
or posttraumatic scarring and is solid rather
than cystic. Fibrous plaques of the tunica albuginea
may calcify.
Because they are so small and they are not sm-rounded
by testicular parenchyma, cysts of the tunica
albuginea are occasionally difficult to find sonographically.
This is true of other small peripheral masses as
well. One technique that is useful is to place a finger
over the lesion and then rotate the testis so that the
palpable lesion is posterior. Then the transducer can be
placed on the anterior aspect of the testis so that the
palpating finger can be seen along the deep surface of
the testis. Once the finger is located, the nature of the
underlying palpable abnormality can usually be determined.
In many cases, cysts of the tunica albuginea will
satisfy all criteria for a simple cyst. However, the smaller
lesions may contain artifactual internal echoes and may
not demonstrate increased through transmission.

Front 90

G rey-scale views of the kid n ey in fou r patients.
1 . Describe the abnormalities shown in these images.
2 . What is the differential diagnosis?
3. What is the role of percutaneous biopsy in lesions such as these?
4. Will CT or MRI assist in the differential diagnosis of these lesions?

Back 90

Renal Cell Carcinoma
1. The first unage shows an entirely solid-appearing
mass in the upper pole of the kidney that is slightly
hyperechoic to the renal parenchyma and produces
a bulge in the external renal contour. The second
image shows a predominantly solid mass Ul the
lower pole of the kidney that is slightly
hyperechoic and has several small, cystic
components. The third image shows a small,
homogeneous, hyperechoic mass. The fourth image
shows a homogeneous, hypo echoic mass.
2. Cortical-based renal tumors such as renal cell
cancer, angiomyolipoma, oncocytoma, lymphoma,
or metastasis can all appear as a solid or
predominantly solid mass.
3. The role of percutaneous biopsy is limited. Most
lesions such as these will be resected regardless of
the results of a biopsy. If there is a prior history of
lymphoma or of another primary tumor likely to
metastasize to the kidney, then biopsy would be
useful, SUlCe a diagnosis of renal lymphoma or
metastatic disease would not require surgery.
Biopsy may also be necessary when it is not
possible to distinguish neoplasm from infection on
clinical and radiologic grounds.
4. CT or MRI would be helpful in evaluating the small,
hyperechoic lesion because it could be an
angiomyolipoma. It is unlikely that CT or MRI
would help Ul further evaluating the other tlu'ee
solid renal lesions. However, CT and MRI provide
valuable staging uuormation, and one or the other
should be performed prior to surgery.
Reference
Forman HP, Middleton WD, Melson GL, McClennan Bi:
Hyperechoic renal cell carcinomas: Increase in detection
at US. Radiology 1993 ; 1 88:43 1 -434.
Cross-Reference
Ultrasound: THE REQUISITES, pp 89-93 .
Comment
Renal cell carcinoma (RCC) is the most common solid
renal neoplasm Ul the adult patient population. RCC is
an adenocarcinoma arising from tubular cells. The most
common histologic subtype is the clear cell type. Other
types ulClude papillary, granular cell, and sarcomatoid.
In the past, the majority of RCCs were detected in
patients with symptoms such as hematuria. Currently,
approximately 50% of RCCs are discovered incidentally
during sonograms or CTs done for other reasons. For
this reason, RCCs are now being discovered at smaller
1 00
sizes. Because surgical resection is the only effective
treatment for RCC, detecting tumors when they are
smaller and of lower stage has been one of the factors
leading to improved survival.
The majority of renal cell cancers are solid neoplasms.
They vary in echogenicity, but the majority are
slightly hyperechoic to the adjacent renal parenchyma
(first image). This is not hard to understand because the
normal renal parenchyma is the most hypoechoic tissue
Ul the upper abdomen. Approximately 1 0% of all RCCs
are markeclly hyperechoic compared to renal parenchyma
and approximate the echogenicity of renal sinus
fat (third unage). Small renal cancers are even more
likely to have this appearance. These are the types that
can simulate an angiomyolipoma. A minority of RCCs
appear either isoechoic or hypoechoic to the renal cortex
(fourth i mage). Isoechoic RCC is detected only
when it is large enough to distort the renal contour.
Small cystic components or areas of hemorrhage or
necrosis are common (second image). Color Doppler
typically will identify internal vascularity in RCC, but
RCC is usually less vascular than the adjacent renal
parenchyma. Small tumors and hypovascular tumors
may have no detectable flow on color Doppler.
The differential diagnosis of solid renal neoplasms
includes other malignant tumors such as transitional cell
cancer, medullary cancer, renal sarcoma, metastases,
and lymphoma. Patients with metastases and lymphoma
almost always have a history of prior lymphoma or
extrarenal malignancy or have imaging evidence that
suggests lymphoma or metastatic disease . M edullary
cancer occurs in patients with sickle cell trait. Transitional
cell cancer is typically based in the central aspect
of the kidney, as opposed to the cortex, and is associated
with typical abnormalities on an intravenous pyelogram.
Benign tumors are also a consideration and ulclude
renal adenoma and oncocytoma. It is not clear if there
is a true distinction between renal adenoma and small,
well-differentiated RCC. Oncocytoma is a variety of adenoma
that has large cells with small, round nuclei and
abundant eosinophilic cytoplasm and numerous mitochondria.
In general, it is not possible to distinguish
RCC from benign renal tumors with imaging tests. The
exception is angiomyolipoma, which can be diagnosed
by CT or MRI when fat is detected.

Front 91

Two views of the l iver.
1 . What types of transducers have been used?
2. Which transducer shows the abnormality best?
3. What is the differential diagnosis?
4. Is there a role for Doppler sonography in establishing this diagnosis?

Back 91

Cirrh osis
1 . The first image was obtained with a 3 . 5 MHz
curved array transducer. The second was obtained
with a 7.5 MHz phased linear transducer.
2 . The second image shows a coarsened and nodularappearing
liver parenchyma better than does the
first image.
3. Cirrhosis is the most likely diagnosis. Metastatic
disease, lymphoma, extensive hepatocellular cancer,
and patchy fatty infiltration can also produce diffuse
liver heterogeneity.
4. Doppler sonography can help in patients with
suspected cirrhosis by finding portal systemic
collaterals or other evidence of portal hypertension.
This confirms the diagnosis of liver disease and
helps to assess disease severity.
Reference
Mergo PJ, Ros PR, Buetow PC, Buck JL: Diffuse disease
of the liver: Radiologic-pathologic correlation. Radiograpbies
1 994; 1 4 : 1 29 1 - 1 307.
Cross-Reference
Ultrasound: THE REQUISITES, pp 18-20.
Comment
Cirrhosis is a diffuse hepatic parenchymal process consisting
of hepatocellular death, cellular regeneration,
and fibrosis. It is divided into a micro nodular form,
when the regenerating nodules are less than 1 cm in
size, and a macronodular form, when the nodules are
greater than 1 cm in size. Sonographic signs of cirrhosis
u

Front 92

Pulsed Doppler waveforms from the left and right su bclavia n veins.
1 . Which subclavian vein waveform is abnormal?
2 . What does the abnormality indicate?
3. Is the superior vena cava likely to be normal in this patient?
4. What is the Significance of reversed flow in the right and left internal mammary veins?

Back 92

S u bclavian Vei n Obstruction
1 . The left subclavian vein is normal. The right
subclavian veU1 is abnormal.
2. The abnormality indicates some type of venous
obstruction between the place where the sample
was taken and the right atrium.
3. SU1ce there is normal pulsatility in the left
subclavian vein, the superior vena cava must be
patent.
4. Reversed flow U1 the u1ternal mammary veins
indicates collateral flow owu1g to central venous
obstruction, usually of the superior vena cava.
Reference
Patel MC, Berman LH, Moss HA, McPherson SJ: Subclavian
and u1ternal. jugular veins at Doppler US: Abnormal
cardiac pulsatility and respiratory phasicity as a
predictor of complete central occlUSion. Radiology
1 999; 2 1 1 : 579- 583 .
Cross-Reference
Ult1-asound: THE REQUISITES, pp 486-487.
Comment
Doppler detection of subclavian ve in t h rombosis i s
more complicated than detection o f lower extremity
deep vein thrombosis because the thrombus frequently
occurs Ul the central aspect of the vein, where the
overlying bones (especially the clavicle) make compression
unpossible, and where visualization is U1 any case
difficult or unpossible. Therefore, the diagnosis often
relies on secondary signs of obstruction. Since the subclavian
vein is relatively close to the right atrium, the
pressure fluctuations in the atrium are readily transmitted
U1tO the vein and produce a pulsatile waveform.
When there is a venous obstruction between the heart
and the site where the Doppler waveform is obtained,
the normal pulsatility is blunted. The asymmetry U1 the
right and left subclavian waveforms is well demonstrated
Ul this case. It is also unportant to realize that
many cases of subclavian vein thrombosis are associated
with jugular veUl tlu-ombosis. Since the jugular vein is
easy to evaluate with sonography, it should be a routule
part of an upper extremity venous Doppler examination.
Although venous thrombosis is the most common
cause of asymmetriC waveforms, it should be realized
that any obstructing process, such as venous stenosis or
extrulsic compression, is a potential cause.

Front 93

Transverse and longitudinal views of the left lobe of the l iver.
1 . What is the abnormality shown in this case?
2. In what direction is the blood flowing?
3 . Where does this abnormality communicate with the portal venous system?
4. How does this blood flow return to the heart?

Back 93

U m b i l ical Vein Collateral
1 . A vascular structure is seen in the ligamentum
teres. This represents a recanalized umbilical vein.
2 . Because the recanalized umbilical vein functions as
a portosystemic shunt, blood flow is directed away
from the liver (hepatofugal).
3. The umbilical vein communicates with the portal
system at the anterior aspect of the terminal
segment of the left portal vein. The ductus venosus
communicates with the posterior aspect of this
portion of the left portal vein. Therefore, in the
fetus, this segment of the portal vein contains
umbilical venous flow. That is why this segment of
the left portal vein is called the umbilical segment.
4 . The umbilical vein travels inferior to the liver along
the deep aspect of the abdominal wall toward the
umbilicus. It eventually connects to the inferior
epigastric veins, which then drain into the femoraliliac
system. In some cases the umbilical vein turns
superiorly to communicate with the superior
epigastric veins and the internal mammary veins.
Reference
Gibson RN, Gibson PR, Donlan ]D, Clunie DA: Identification
of a patent paraumbilical vein by using Doppler
sonography: importance in the diagnosis of portal
hypertension. AIR Am I Roentgenol 1 989; 1 53 :
5 1 3 - 5 1 6.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 9- 2 2 .
Comment
The umbilical vein is the portosystemic collateral that is
the easiest to visualize sonographically. It has a constant
relationship with the portal venous system; it always
commlllicates with the umbilical segment of the left
portal vein. Therefore, it can be seen between the medial
and lateral segments of the left lobe within the
ligamentum teres. In some normal individuals, the fibrous
remnant of the obliterated umbilical vein can be
seen as a hypoechoic band. However, this band should
not exceed 3 mm and should not contain blood flow.
The umbilical vein normally exits the liver and travels
along the anterior abdominal wall toward the umbilicus.
The caput medusa sign refers to prominent visible superficial
collaterals in the periumbilical region and represents
an uncommon manifestation of umbilical vein
collaterals. In patients with suspected portal hypertension,
this is one of the potential collaterals that should
be investigated to help confirm the diagnosis.

Front 94

Longitudinal views of the l eft upper quadra nt. (See color pl ates.)
1 . Describe the abnormality that is being measured.
2. How common is this abnormality?
3. From where does the blood supply come?
4. What further evaluation is necessary?

Back 94

Splenule
1 . The lesion being measured is a solid mass that is
isoechoic to the spleen with detectable internal
vascularity. This appearance is typical of a splenule.
2. Splenules are seen in up to 30% of autopsies.
3. Blood supply to splenules is from the splenic artery.
4 . This is a common finding that requires no further
evaluation.
Reference
Subramanyam BR, Balthazar E], Horti Sc. Sonography of
the accessory spleen. AIR Am I Roentgenol 1 984;
1 43 :47-49.
Cross-Reference
Ultrasound: THE REQUISITES, P 1 42 .
Comment
Splenules are also referred to as splenunculi, accessory
spleens, and supernumerary spleens. As indicated in the
answer to question 2, they are very common and are
frequently seen as incidental findings on imaging studies
of the left upper quadrant. They are typically small
leSions, measuring less than 3 cm in size. Small splenules
may enlarge and become m ore readily evident
when the spleen itself enlarges, or following a splenectomy.
Although typically solitary, approximately 1 0% of
splenules are multiple. In addition to the splenic hilum,
accessory spleens can occur in the tail of the pancreas
or in the suspensory ligaments of the spleen.
Under unusual cirCllllstances, it may be necessary to
confirm that a mass in the left upper quadrant with
sonographic findings typical for a splenule is in fact
functioning splenic tissue. For instance, in a patient
with a suspected islet cell tumor of the pancreas, a
splenule may cause diagnostic confusion. The best way
to document that a lesion is a splenule is to perform
either a sulfur colloid scan or a heat-damaged tagged
recl blood cell scan.

Front 95

Lon gitudinal view and extended field of view scan of the neck i n a
patient with recu rrent hyperpa rathyroidism followi ng prior neck
exploration.
1. Is imaging useful in patients such as this one?
2 . Is a nodule lateral to the carotid artery more likely to be a lymph node or a parathyroid adenoma?
3. What is the sensitivity of ultrasound in detecting this abnormality in patients who have had prior
neck dissection for hyperparathyroidism?
4. What is the incidence of this lesion?

Back 95

Ectopic Parathyroid Adenoma
1. Imaging is most useful in localizing parathyroid
adenoma following prior neck exploration.
2. Parathyroid adenomas are almost always medial to
the carotid artery. A nodule seen lateral to the
carotid is much more likely to be a lymph node.
3. The sensitivity is 60% to 80%.
4. The incidence of ectopic parathyroid nodules is
approximately 1 0%.
Reference
DeFeo ML, Colagrande S, Bianini C, et al: Parathyroid
glands: Combination of 99m Tc MIBI scintigraphy
and US for demonstration of parathyroid glands and
nodules. Radiology 2000; 2 1 4:393-402 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 452-454.
Comment
One of the important reasons for a failed parathyroid
operation is the presence of an ectopic adenoma. There
are a number of potential ectopic locations. Behind the
trachea or in the tracheoesophageal groove is a common
ectopic location. These lesions can best be visualized
by scalU1ing from a lateral approach and having the
patient turn his or her head away from the side being
scanned. Other ectopic sites are low in the neck (as in
this case) or in the mediastinum. Lesions in these sites
can be a challenge to see, especially with a linear array
transducer, which is usually used to scan the neck.
Switching to a sector or cmved array transducer can
allow for better flexibility in the suprasternal area. In
fact, a transvaginal probe is an excellent choice for
looking into the superior mediastinum because it has a
very small footprint. Intrathyroidal adenomas are rare
but do occm. They have a sinular appearance and orientation
to other parathyroid adenomas and usually occur
in the posterior aspect of the thyroid. Finally, ectopiC
adenomas can occur within the carotid sheath as lugh
as the bifurcation.
Preoperative inlaging of patients at their initial presentation
with hyperparathyroidism is controversial. Experienced
surgeons have a high success rate and a low
complication rate without any preoperative localization.
Less experienced surgeons can often benefit from preoperative
imaging, since unilateral exp lo rations can
then be performed, and operative time can be diminished.
On the other hand, even experienced neck surgeons
benefit from the information provided by preoperative
imaging in patients who have recurrent or
persistent hyperparathyroidism after a previous neck
exploration.
Other modalities used to identify parathyroid adenomas
include scintigraphy, MR!, CT, angiography, and
1 06
venous sampling. At my own institution, the combination
of ultrasound and scintigraphy with technetium-
99m sestamibi is the standard procedure for imaging
patients with recurrent or persistent hyperparathyroidism.

Front 96

Sag ittal grey-scale view of the lateral prostate and transverse color
Doppler view of the right prostate i n two patients.
1 . Describe the abnormalities.
2 . What is the most common location for prostate cancer?
3. Where is benign prostatic hypertrophy (BPH) located?
4. Is prostate cancer more often hypoechoic or hyperechoic?

Back 96

Prostate Cancer
1 . The abnormality on the grey-scale view is a
hypoechoic nodule in the peripheral zone of the
prostate. The abnormality on the color Doppler
view is a hypervascular nodule in the peripheral
zone. Although these findings are nonspecific, they
are very typical of prostate cancer.
2. Seventy percent of prostate cancers occur in the
peripheral zone.
3. Benign hypertrophy occurs in the central gland.
4. Prostate cancer is usually hypoechoic.
Reference
Choyke PL: Imaging of prostate cancer. Abdom Imaging
1 995 ; 20:505 - 5 1 5 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 458-460.
Comment
Prostate cancer is the most common malignancy in
men. Ten percent of American men will be diagnosed
with prostate cancer. Autopsy studies show that 20% of
men between the ages of 40 and 60 and 60% older than
age 80 have prostate cancer. Therefore, as screening for
prostate cancer becomes more universal, the number of
newly diagnosed patients will increase. Although the
risk of dying from prostate cancer is only 2% to 3%, the
tumor is so common that it is still the second leading
cause of cancer death in men.
Men are screened for prostate cancer using digital
rectal examination (DRE) and prostate-specific antigen
(PSA) screel1ing. Transrectal ultrasonography (TRUS) is
used primarily to guide the biopsy of lesions felt on
DRE, of lesions that are visible on TRUS, or of random
areas of the prostate . TRUS is also used to measure the
prostate so that volume-adjusted PSA (pSA density or
PSAD) can be determined. TRUS is no longer used to
screen for cancer.
Most prostate cancers are hypoechoic, but only 20%
of hypoechoic lesions are cancer. Isoechoic cancer is
also common, so ultrasound guided biopsies should be
directed at random sites (usually the upper, nud, and
lower third of the gland bilaterally) as well as at any
visible lesion.

Front 97

Lon g itudinal color Doppler views and pulsed Doppler waveforms from
the carotid bifurcation. (See color plates.)
1 . Identify the internal and external carotid arteries.
2 . Do both vessels appear normal?
3. If this patient had a history of transient ischemic attacks, would he benefit from a carotid
endarterectomy?
4. What is the most common site for carotid plaque formation?

Back 97

Low-Grade I nterna l Carotid Stenosis
1 . In these images, the deep vessel is the internal and
the superficial vessel is the external carotid artery.
The internal waveform has a broader systolic peak
with a more gradual deceleration into diastole. The
external waveform has less diastolic flow.
2 . The external carotid artery appears normal.
Hypoechoic plaque is present at the origin of the
internal carotid artery.
3 . The peak flow velocity in the internal carotid artery
is 1 54 cm/sec. This is elevated and would predict a
stenosis of 40% to 60% of the arterial diameter.
Endarterectomy is indicated for symptomatic
patients when the stenosis exceeds 70%.
4. The location of plaque in this patient is the most
common site, at the junction of the carotid bulb
and the internal artery origin opposite the flow
divider.
Reference
North American Symptomatic Carotid Endarterectomy
Trial Collaborators: Beneficial effect of carotid endarterectomy
in symptomatic patients with high-grade
stenosis. N Engl] Med 1 99 1 ;3 2 5 : 445-453.
Cross-Reference
Ultrasound: THE REQUISITES, pp 470-477.
Comment
Carotid Doppler imaging is used as a noninvasive way
to detect atherosclerotic plaque and to estimate the
degree of stenosis caused by the plaque. Early plaque
formation is detected on grey-scale imaging as minimal
thickening of the vessel wall. With progressive changes,
the resulting luminal narrowing can be seen with both
grey-scale and color Doppler imaging. Velocity increases
begin to occur when the stenosis exceeds 40% to 50%
of the diameter of the artery. Based on the results of
the North American SymptomatiC Carotid Endarterectomy
Trial study, patients with neurologic symptoms
benefit from carotid endarterectomy if the diameter
stenosis (determined from a carotid arteriogram) is 70%
or greater. In measuring the lesion, it is inlportant to
calculate the percentage of stenosis based on comparison
of the lumen diameter at the stenotic site with that
at a distal site where the diameter is normal.
The criteria for categorizing carotid stenosis are not
uniformly agreed upon. In general, the higher the velocity,
the greater the stenosis. Color Doppler is usually
very useful in identifying the site of peak velOcity, so
placement of the pulsed Doppler sample volume can
be precise. In this case, an area of aliaSing is seen in the
internal carotid origin indicating the site of the high
velOCity flow jet. The angle corrected pulsed Doppler
1 08
waveform from this site shows that the peak systolic
velOCity is 1 54 cm/sec. The cutoff velocity used to
indicate a stenosis of greater than 70% diameter narrowing
is usually 200 cm/sec or higher.

Front 98

Long itudinal color Doppler views of the left hepatic vei n . (See color plates .)
1 . Why is blood flow seen better on the second image?
2. Why does the liver appear brighter on the second image?
3. Besides the technical control responsible for improved Doppler sensitivity in the second image, what
two other controls are most important in increasing Doppler sensitivity?
4. If all other things are equal, what technical parameter should be adjusted first when attempting to
improve Doppler sensitivity?

Back 98

Effect of Power Output on Color Doppler
I mages
1 . The power output was increased in the second
image.
2. For the same reason. The power output affects both
the color unage and the grey-scale image.
3. Doppler gaul and Doppler scale are two basic
controls that affect color sensitivity.
4. Doppler gaul, because this does not affect patient
exposure and does not increase the chance of
aliaSing.
Reference
Middleton WD: Color Doppler image optin1ization and
interpretation. Ultrasound Q 1 998; 1 4 : 1 94 -208.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-470.
Comment
Power output is one of several controls that will affect
the color image. Power output refers to the strength
of the transmitted ultrasound pulse. Stronger or more
powerful sound pulses will produce stronger reflections
that are more easily detected. Power output affects both
the grey-scale and color Doppler image. In general,
increasing the power output unproves color Doppler
sensitivity. This can be very important in deep abdominal
applications, where tissue attenuation Significantly
weakens the Doppler signal. However, increasulg the
power output also causes increased patient exposure
and can lead to a number of artifacts. Therefore, power
levels should be kept as low as is reasonably achievable
in order to obtaul the desu-ed information.
The two other basic controls that affect Doppler
sensitivity are the Doppler gaUl and the Doppler scale.
The Doppler gain electronically amplifies the Doppler
signals received by the transducer. It also amplifies electronic
noise. Therefore, it can be increased until imagedegrading
color-noise artifact is produced. Color Doppler
sensitivity can also be improved by decreaSing the
color Doppler scale. The sacrifice is that aliasulg artifacts
may develop at low scales. With power, color
gain, and color Doppler scale, it is worth realizing that
attempts at improving sensitivity can have a paradoxical
effect when they are adjusted to extreme levels.

Front 99

Transverse and longitu d i n a l views of the l iver.
1 . Describe the abnormality.
2 . What is the differential diagnosis?
3. Given the compression of the liver, where is this lesion likely located?
4. What would the diagnosis be if this lesion contained bright reflectors with ring-down artifacts?

Back 99

Hepatic S u bcapsular Hematoma
1 . The lesion is a complex fluid collection with lowlevel
echoes and multiple internal septations.
2. The most likely diagnosis is hematoma. Other
considerations include abscess and biloma.
3. Compression of the liver parenchyma suggests that
tllis hematoma is subcapsular.
4. Distinguishing an abscess or an infected hematoma
from a simple hematoma is very difficult. Ringdown
artifacts usually indicate gas, and the
presence of gas is a clue that there are gas-forming
organisms present and thus allows for a diagnosis of
infection. In the absence of gas, aspiration of the
fluid is necessary if there is clinical concern about
infection.
Reference
VanSonnenberg E, Simeone ]F, Mueller PR, et al: Sonographic
appearance of hematoma in liver, spleen and
kidney: A clillical, pathologic and allimal study. Radiology
1 983 ; 1 47: 507- 5 1 0 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 06- 1 09 .
Comment
Hematomas have a range of sonographic appearances
depending primarily on tlleir age. In the acute stage,
they usually appear as a complex collection with solid
and cystic components. If the proportion of clot predominates
over the proportion of serum, then a hematoma
may sinlUlate a solid mass. With time, the clotted
portion of the hematoma lyses, and the collection becomes
more liquefactive. In this stage, s o nography
shows a complex fluid collection, usually with some
combination of septations, i nternal fibrinous membranes,
and fluid/fluid levels. Eventually, most hematomas
liquefy completely and appear entirely cystiC on
sonography. The time of evolution of these sonograpllic
changes varies greatly from one patient to the next. It
typically takes a matter of weeks. In this case, the
hematoma was in the subcapsular space and was caused
by a liver biopsy. Trauma is the other most common
cause of subcapsular hematoma.
Hematomas should always be considered when a
complex fluid collection is identified sonographically.
An abscess should also be included in the differential
diagnosis. Other fluid collections should be conSidered,
depending on the organ involved. In the case of the
liver, a biloma is another consideration. If this collection
were adjacent to the kidney, a urinoma would be a
possibility.

Front 100

long itud i n a l views of the patellar tendon.
1 . Which view shows a normal patellar tendon?
2. What is the differential diagnosis for a hypoechoic tendon?
3. Are nerves more or less echogenic than tendons?
4. Does ultrasound demonstrate the internal fibers of tendons as well as MRI?

Back 100

Normal Tendon Anisotropy
1 . The patellar tendon is normal in both views. In
fact, it is the same tendon imaged once with the
long axis parallel to the transducer and again with
the long axis at an angle to the transducer.
2. Decreased echogenicity in a tendon may indicate
tendinitis or a partial tear, or it may be due to
anisotropy.
3 . When imaged at 90 degrees, tendons are more
echogellic than nerves.
4. Ultrasound displays the internal fibers of tendons
better than MRI.
Reference
Martinoli C, Bianclli S, Derclli LE: Tendon and nerve
sonography. Radiol Clin North Am 1 999;37:69 1 -7 1 1 .
Cross-Reference
Ultrasound: THE REQUISITES, P 455.
Comment
Sonography displays the internal architecture of tendons
better than any other modality. When imaged so that
the sound reflects off the tendon at 90 degrees, the
interfaces between tendon collagen and internal endotendineum
septa produce strong specular reflections.
Tllis results in an appearance of bright, closely spaced,
parallel, linear reflections within the substance of the
tendon. When tendons are imaged at less than 90 degrees,
the internal reflectors no longer act as specular
reflectors, and the tendon becomes hypoechoic, and
the internal fibrillar pattern is no longer seen. Tllis
effect (variable echogellicity depending on the relative
orientation of the transducer and the tendon) is referred
to as allisotropy. A1lisotropy is present in many parts of
the body but is particularly prominent in tendons.
Under most circumstances, tendons should be imaged
at 90 degrees so that the internal fibrillar pattern
is visible. However, when tendons are surrounded by
echogenic tissue such as fat, it may be helpful to purposely
angle the transducer so that the tendon appears
hypoechoic and the contrast between tendon and peritendinous
tissues is increased. In addition, echogenic
lesions and abnormal intratendinous interfaces are occasionally
best seen when the tendon itself is purposely
made to appear hypoechoic by imaging at less than
90 degrees.

Front 101

Two views of the l iver.
1 . Describe the abnormality.
2 . What is the most common cause of this abnormality?
3. What would you consider if this finding were associated with dilated loops of small bowel?
4. Is this abnormality seen most often in the right or left lobe?

Back 101

I ntrabiliary Air
1. Both images show very bright, linear, branching
structures in the liver. The second image shows a
faint ring-clown artifact arising from one of these
structures.
2. Biliary air is most often caused by stents and
surgical anastomosis between bile duct and bowel.
3. Biliary air and a small-bowel obstruction should
raise the possibility of gallstone ileus.
4. Biliary air tencls to move to the nondependent areas
of the liver. Therefore, it is seen in the left lobe
when patients are supine and in the right lobe
when patients are in a left lateral decubitus
pOSition. This rule is frequently broken because free
movement of the air is limited.
Reference
Middleton WD: The bile ducts. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1 993, pp 1 46- 1 72.
Cross-Reference
Ultrasound: THE REQUISITES, pp 6 1 -63.
Conunent
Biliary gas is a common finding following various manipulations
of the bile ducts. Biliary enteric anastomoses
and biliary stents are probably the most common source
of biliary gas. Endoscopic sphincterotomy is another
common cause. Biliary enteric fistulas can also cause
biliary gas but are much less common. Erosion of a
gallstone through the gallbladder (or, less often, through
the bile duct) into the bowel (usually the duodenum) is
the most common cause for a biliary enteric fistula.
Erosion of a duodenal or pyloric ulcer into the bile duct
or gallbladder is another cause of a fistula.
On sonography, biliary air appears as a bright reflection
in the lumen of the bile ducts. As with gas elsewhere,
it often causes a ring-down artifact. It is generally
most prominent in the nondependent portions of the
biliary tree. Gas can be seen in the common duct, but
this phenomenon is less common than in the intrahepatic
ducts.
The differential diagnosis of pneumobilia includes
intrallepatic bile duct stones, portal venous gas, and
calcified hepatic arteries. Intrahepatic stones are usually
less echogenic than air and do not produce ring-down
artifacts. In addition, intrahepatic ductal stones are generally
nonmobile and do not predominate in the nondependent
portion of the liver. Portal venous gas call be
confused with biliary air when it is confined to the
peripheral intrahepatic portal veins. In such cases, careful
grey-scale scanning of the more central portal veins
1 1 2
often shows mobile bubbles flowing in the venous lumen.
Pulse Doppler waveform analysis may also show
characteristic spikes in tlle venous waveform that are
indicative of portal vein gas. Hepatic arterial calcification
can be as bright as air but is not mobile, does not
produce ring-down artifacts, and does not predominate
in the nondependent portion of the liver. When there
is still confusion, abdontinal radiographs can assist in
differentiating biliary gas from the other entities mentioned
here.

Front 102

Long itudinal view of the pla ntar fascia of both feet.
1 . Which side is abnormal?
2. What symptoms is this patient likely to have?
3. Is imaging required to make this diagnosis?
4. What is the etiology?

Back 102

Plantar Fasciitis
1. The second image, showing the thicker plantar
fascia, is abnormal.
2. The common symptoms are inferior heel pain and
tenderness that worsens with prolonged activity.
3 . Generally the diagnosis is made based on clinical
evaluation, and imaging is not required.
4. The etiology is repetitive microtrauma.
Reference
Cardinal E, Chhem RK, Beauregard CG, et al: Plantar
fasciitis: Sonographic evaluation. Radiology 1 996;
20 1 : 257-259.
Cross-Reference
Ultrasound: THE REQUISITES, pp 455 -456.
Conunent
Plantar fasciitis is the most common cause of inferior
heel pain. It occurs most commonly as a result of repetitive
nticrotrauma in athletes engaged in activities such
as running, danCing, tennis, and basketball. It may affect
up to 1 0% of running athletes but can also occur in
nonath1etes . It can be exacerbated by prolonged weightbearing
and obeSity. Rheumatologic conditions such as
rheumatoid arthritis, systentic lupus erythematosus, Reiter's
disease, and ankylosing spondylitis may also cause
plantar fasciitis.
In most cases the diagnosis can be made based on
the cllitical ltistory and physical examination. In atypical
cases, sonography can be very helpful. The sonograpltic
findings are tltickening and, in some cases, decreased
echogenicity of the fascia. In almost all instances, the
fascia is tltickest proximally at the site of attachment to
the calcaneus. When the symptoms are unilateral, the
asymptomatic side should be used as a base line for
comparison of the thickness and echogenicity of the
plantar fascia. When symptoms are bilateral, studies
have shown that 4 mm is a reasonable upper llillit of
normal for plantar fascia thickness.

Front 103

Grey-scale views of the right ki dney, inferior ve na cava, and right re nal
vein, and power Doppler view of the right re nal vein.
1. Describe the abnormalities.
2. What is the most likely etiology of the abnormalities?
3. How common is this?
4. Is ultrasound a good way of evaluating this condition?

Back 103

Tumor Thrombus of the Renal Vei n and
I nferior Vena Cava
1 . A soft tissue mass is replacing the entire upper pole
of the right kidney. Soft tissue extends from the
right kidney into the markedly distended renal vein
and inferior vena cava (lYC). Detection of internal
vascularity on Doppler confirms that tins is tumor
thrombus.
2. Renal cell carcinoma CRCC) is almost always the
cause of renal vein tumor thrombus.
3. Traditional estimates indicate that renal vein
invasion occurs in up to 20% of patients with RCC,
and IVC invasion occurs in up to 1 0% of patients.
However, most renal cell cancers are now detected
as incidental masses in patients undergoing CT or
ultrasound for other reasons, and venous invasion is
much less common in tins group of patients.
4. Ultrasound is probably similar to CT and MRJ in
detecting clinically significant tumor thrombus and
determining the extent in patients with RCe.
References
Bechtold RE, Zagoria RJ: Imaging approach to staging
of renal cell carcinoma. Urol Clin Nort/:J A m
1 997; 24: 507 - 5 2 2 .
Schwerk WB, Schwerk WN, Rodeck G: Venous renal
tumor extension: A prospective US evaluation. Radiology
1 985; 1 56:49 1 -495.
Cross-Reference
Ultrasound: THE REQUISITES, P 92.
Comment
RCC is the most common renal neoplasm. Survival is
directly related to the stage and grade of the tumor.
Chemotherapy and radiation therapy have little effect
on RCC, so surgery is the only effective therapy at
present. Imaging is critical in the preoperative evaluation
of patients with RCC because it determines the
surgical approach and the prognosis for patients who
are not surgical candidates. The most common staging
system used for RCC is the Robson system. In this
system, stage I disease is tumor confined to the renal
capsule. Stage II is tumor that has invaded the perineplu"
ic fat . Invasion of the renal vein or IVC indicates
stage IlIA disease. Stage IIIB disease includes regional
lymph node metastases. Stage IIIC disease has combined
nodal and venous metastases. Direct invasion of adjacent
organs indicates stage IVA, and distant metastases
are stage IVB.
Tins case demonstrates stage IlIA disease, with invasion
of the renal vein and the IVe. It is very uncommon
1 1 4
for tumors smaller than 4 cm to invade the veins . In the
majority of cases, tumor simply grows into the lumen
of the vessel but does not invade the wall of the vessel.
Interestingly, the prognosis is similar for stage IlIA disease
and for tumor confined to the kidney. In fact, the
prognosis is largely independent of the extent of IVC
involvement. However, it is very important to detect
and quantitate venous involvement because this dictates
the surgical approach. If tumor extends into the supradiaplu"agmatic
cava, then a combined thoracoabdominal
approach is necessary, and cardiopulmonary bypass
should be available. The relationship of (he tumor to
the hepatic veins is also important because the IVC can
be clamped below the level of the hepatic veins, provided
there is no tumor thrombus at that level.
In most patients, ultrasound is very good at detecting
thrombus in the IVC and at identifying the superior
extent. Detection of renal vein involvement is also usually
possible, with the sensitivity depending on the extent
of venous involvement. CT or MRJ are almost always
used to stage patients with RCC, and both tests are
complementary to ultrasound in evaluating the status of
the renal veins and IVe. In some patients, flow-related
artifacts and other problems can make interpretation of
venous and IVC invasion difficult on CT or MRJ. In
these Situations, ultrasound is an excellent problemsolving
tool.
In many cases, including the one shown here, the
vascularity of the tumor thrombus can be documented
with color or power Doppler. This distinguishes tumor
thrombus from bland thrombus. Realize that the inability
to detect intratumoral flow does not exclude the
possibility of tumor thrombus. Also realize that venous
thrombus in the setting of RCC is almost always tumor
thrombus.

Front 104

Tran sverse color Doppler views of the portosplenic confl uence a n d the
superior mesenteric a rtery. (See col o r plates.)
1 . Why is blood flow not demonstrated in the vessels in the first image?
2. What does PRF stand for?
3. Is the PRF dependent on the Doppler gain?
4. Is the PRF dependent on the inlage depth?

Back 104

Effect of Doppler Scale on Doppler
Sensitivity
1 . Blood flow is poorly seen on the first image
because the Doppler scale is too high ( ± 74 cm/
sec). The scale has been readjusted in the second
image to a more appropriate level ( ± 2 1 cm/sec).
2. PRF stands for pulse repetition frequency. The PRF
determines the Doppler scale.
3. The PRF is independent of the Doppler gain.
4. Deeper fields of view require a longer tinle delay
between sound pulses because each pulse must
travel farther. Therefore the PRF drops as the field
of view deepens.
Reference
Middleton WD: Color Doppler image optimization and
interpretation. Ultrasound Q 1 998; 1 4: 1 94-208.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-470.
Comment
A number of user-adjustable parameters are available to
optimize color Doppler images. The most basic is the
color gain. This is simply a receiver end amplification
of the color signal. In most situations, the color gain
should be increased to a maximum value just prior to
the point where random color noise begins to appear
in nonvascular spaces. The color gain affects only the
color portion of the image and does not affect the greyscale
background or the pulsed Doppler waveform.
The PRF refers to the number of sound pulses transmitted
per second. The PRF determines the magnitude
of the Doppler scale. Higher scales are produced by
higher PRFs, wIllie lower scales are produced by lower
PRFs. The advantage of a low PRF (low scale) is improved
sensitivity to low-velocity blood flow. The advantage
of a high PRF (l1igh scale) is display of high-velocity
flow without aliasing. On most equipment there is a
control labeled Doppler scale that varies the PRF and
thus adjusts the Doppler scale. The PRF is usually displayed
with the rest of the technical information on the
unage . On these unages, the PRF is 6944 and 1 994
pulses per second.
Another means of ilnproving the sensitivity is to increase
the number of sound pulses used to generate
each individual line of color Doppler information. This
control has been referred to as the "dwell time" or the
"ensemble length" or "color senSitivity." If more pulses
are used for each lUle in the color Doppler unage, then
it will take longer to generate each uldividual color
Doppler frame. Thus, the trade-off is a lowered frame
rate. In some situations where background motion is
limited (such as neck or extremity examinations), a low
1 1 6
frame rate is acceptable. However, Ul other Situations,
background motion requires a higher frame rate (car(
liac, abdominal, and obstetrical scans) and thus there
is a practical limit to the number of pulses that can be
used to generate each color Doppler line.

Front 105

Color Doppler i m age and pu lsed Doppler waveform obtained i n the
region of anastomosis of a hemodialysis a rteriove nous fistula. (See color
pl ates.)
1 . Describe the abnormality shown on the color Doppler image .
2 . Describe the abnormality shown on the Doppler waveform.
3 . What is the explanation for these findings?
4. What pathologic processes can produce these findings?

Back 105

Tissue Vibration
1 . The color Doppler unage shows focal, random
color assignment in the tissues around the vessel.
2. The Doppler waveform shows strong but lowfrequency
Doppler signal symmetrically clisplayed
above and below the base line.
3. Both findulgs are typical of soft tissue vibration.
4. Vibration of the soft tissues is caused by turbulent
flow in the vessels. Usually it is associated with a
stenosis, aneurysm, or arteriovenous fistula.
Reference
Middleton WD, Erickson S, Melson GL: Perivascular
color artifact: Pathologic Significance and appearance
on color Doppler US unagulg. Radiology 1 989;
1 7 1 :647 -65 2 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 64-65 .
Comment
In situations where flow velOCity is extremely high or
where flow is extremely disordered, turbulence may
occur. Turbulence causes pressure fluctuations in the
lumen of the vessel. The pressure fluctuations cause the
vessel wall to vibrate. If the vessel wall vibration is
strong enough, the vibrations are transmitted into the
adjacent soft tissue. TIlis perivascular soft tissue vibration
may be auscultated with a stethoscope as a bruit.
When it is severe, it can be palpated as a thrill.
Tissue vibrations can also be detected on Doppler
scans. Since motion produces a Doppler frequency shift,
the back-and-forth vibratory motion of soft tissue reflectors
is recognized as a Doppler signal and displayed as
random scattered red and blue color assignment centered
around the abnormal vessel. The peak effect is
during systole, when the velocities are the greatest.
During diastole, the perivascular artifact recedes significantly.
On a pulsed Doppler waveform, the signal
from vibratulg soft tissues is symmetric above and below
the base line because the soft tissue reflections are
going back and forth. In addition, the signal is strong
because reflections from soft tissue interfaces are
stronger than the reflections from red blood cells. On
the other hand, since the speed of the vibrational motion
is slow, the size of the pulsed Doppler signal is low.

Front 106

Transverse views of two g a l l b ladders.
1 . Describe the abnormal finding on these images.
2 . What is the diagnosis?
3. How likely is this to be detected with CT?
4. How likely is this to be detected on an abdominal radiograph?

Back 106

Wal l- Echo-Shadow Complex
1 . The finding is a bright curvilinear reflector with a
dense posterior shadow (the echo and shadow) and
a more superficial hypoechoic layer (the wall).
2. This finding indicates a gallbladder that is
contracted and filled with stones.
3. The sensitivity of CT in detecting gallstones is less
than 80%.
4. The sensitivity of radiography in detecting
gallstones is 1 5%.
Reference
Ryubicki FJ: The WES sign. Radiology 2000; 2 1 4:88 1 -
882 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 38-40.
COllllllent
Ultrasound i s used i n many situations because i t i s
cheaper, more readily available, o r safer than alternative
imaging modalities. When it comes to gallstone detection,
ultrasound is used simply because it is better than
alternative modalities. However, in order to maintain a
high sensitivity it is important to detect stones other
than those that appear as the classic mobile, shadowing,
echo genic structure in the lumen of a bile-filled gallbladder.
One situation where stones do not have the classic
appearance is when they completely fill the gallbladder
lumen. In tlus situation, the gallbladder no longer appears
as a fluid-filled (Le . , bile-filled) structure, and thus
it is much more difficult to identify. Instead, a stonefilled
gallbladder appears as an echogenic structure with
posterior shadowing. The problem then becomes distillguishing
the echogeluc, shadowing, stone-filled gallbladder
from the multiple echogeluc, shadowing, gas-filled
loops of bowel.
One means of distmguishing these entities is the wallecho-
shadow (WES) complex that is demonstrated in
this case. The WES sign consists of a hypoechoic layer
(the gallbladder wall), a hyperechoic layer (the leading
edge of the stones), and a shadow. The WES complex
is seen in many, but not all, gallbladders that are filled
with stones. However, it is very unusual to see a WES
complex ill gas-filled bowel loops. Another factor that
aids in this distinction is the nature of the shadow.
Stones typically produce a well-defined, clean shadow.
Gas, on the other hand, produces a less well-defined,
dirty shadow. Finally, the location is also helpful, because
the gallbladder is almost always located adjacent
to the interlobar fissure, between the left and right lobe
of the liver.

Front 107

Views of the l iver i n two patients.
1 . Describe the abnormality in these two patients.
2 . What should be included in the differential diagnosis?
3. Is this lesion easier to diagnose with CT or with ultrasound?
4. What fluid-filled hepatic lesion often looks solid on sonography?

Back 107

Hepatic Abscess
1 . Both images show hypoechoic lesions with
posterior acoustic enhancement.
2. The differential diagnosis is broad. The posterior
enhancement suggests that the lesions are fluidfilled,
and tlus makes abscess and hematoma
possibilities. Solid lesions can also be associated
with some degree of posterior enhancement, so
metastatic disease and hepatocellular cancer are
also considerations.
3. Liver abscesses often appear more characteristic on
CT than on ultrasound.
4. Abscesses can appear solid on ultrasound.
Reference
Singh, Y, Willic A.B, Tabbara SO: Residents' teaching
files: Multiloculated cystic liver lesions: Radiologicpathologic
differential diagnosis. Radiographics 1 997; 1 7 :
2 1 9-224.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 4- 1 6.
COllllllent
The lesions shown ill this case are heterogeneous but
predominantly hypoechoic . The increased through
transn1.ission suggests that the lesion is composed of
fluid. Its sonograpluc appearance is most consistent
with a complex fluid collection such as a hematoma o r
a n abscess. It is not possible to distillguish these two
abnormalities with ultrasound. In a case like this, the
clilucal history is critical. These patients had fever and
leukocytosis, and both were subsequently proven to
have an abscess when the fluid was dramed percutaneously.
Gram-negative bacilli are the most common cause of
pyogenic hepatic abscesses. Escherichia coli is cultured
most often. Up to 50% of abscesses are anaerobic or
mixed aerobic and anaerobic. They usually occur in
the setting of illfectious or illfIammatory disease of the
intestines, biliary tract, or adjacent organs, or are due
to truma or septicenua.
Liver metastases usually appear as solid masses and
typically have a target appearance or are hypoechoic.
Some metastases can have cystic components and could
therefore simulate a hematoma or an abscess. If patients
ill tlus case had a Ius tory of a prior malignancy, then
metastatic disease to the liver would be a consideration.
Hepatocellular cancer is usually entirely solid, but it may
demonstrate increased through transnussion and ill the
proper clinical setting would also be a consideration

Front 108

Views of the right lobe of the liver and of the porta hepatis
in two patients.
1 . Describe the abnormal findings .
2. What is the normal blood flow velocity in the portal vein?
3 . What is the sensitivity of color Doppler in detecting the abnormality shown in this case?
4. What sorts of conditions predispose patients to this abnormality?

Back 108

Portal Vei n Thrombosis
I . Both images show localized material in the lumen
of the portal vein that is typical of nonobstructive
thrombosis.
2. Normal portal vein flow velocity is approximately
20 cm/sec.
3. Ultrasound with color Doppler is very sensitive to
portal vein thrombosis and is an appropriate initial
study in patients suspected of having this diagnosis.
4. Hypercoagulable states of any sort, metastatic
disease, abdominal infections or inflammatory
conditions, trauma, and pregnancy predispose
patients to portal vein thrombosis.
Reference
Tessler FN, Gehring B], Gomes AS, et al: Diagnosis of
portal vein thrombosis: Value of color Doppler imaging.
AJR A m ] Roentgenol I 99 1 ; 1 57: 293-296.
Cross-Reference
Ultrasound: THE REQUISITES, pp 2 3 - 2 5 .
Comment
Portal vein thrombosis may appear hyperechoic, isoechoic,
hypoechoic, or anechoic. When the thrombus
is clearly seen on grey-scale sonography, the diagnosis
is easy. However, hypoechoic or anechoic thrombus
can be difficult to distinguish from low-level artifactual
echoes that are often seen in the portal vein. In such
cases, color Doppler is important in establishing the
diagnosis. With occlusive thrombus, no flow is detectable
in the affected segment of the portal vein. With
nonocclusive thrombus, a flow void is present in the
affected segment.
One limitation of color Doppler is that a patent portal
vein may have very slow flow that calUl0t be detected
with color Doppler. Therefore, whenever the diagnosis
of portal vein thrombosis is being entertained based on
lack of detectable flow, but thrombus is not confinned
on grey-scale imaging, the possibility of slow flow
should also be considered. Careful attention should be
paid to technical parameters that affect Doppler sensitivity
so that detection of slow flow is maximized. Because
portal vein flow increases after eating, postprandial
scans can also help in detecting slow portal venous flow.
If flow remains undetectable despite these maneuvers,
portal vein thrombosis is probably present. However,
slow flow remains a possibility, and other tests should
be obtained to help make this distinction. Contrast enhanced
Doppler should also help with this distinction.
Another pitfall of color Doppler is that it can obscure
focal nonobstructive thrombus that may be easy to see
on grey-scale imaging alone.

Front 109

Transverse view and longitudinal extended-field-of-view scan
of the mid abdomen.
1. What abnormality is demonstrated in this patient?
2. What two conditions are most likely?
3. If you were performing a biopsy on this patient, in what should the specimen be stored?
4. Would the presence of central liquefaction affect your interpretation?

Back 109

Lym phoma
1. Both images show multiple hypoechoic solid
masses around the mesenteric vessels and the aorta
and cava. This is typical of lymphadenopathy.
2. Lymphoma and metastatic disease are the primary
considerations for this degree of lymphadenopathy.
3 . Whenever lymphoma is a conSideration, biopsy
specimens should be placed in saline (rather than
formalin) so that flow cytometry can be performed.
This is necessary to subcategorize the type of
lymphoma.
4. Although it occurs, it is unusual to see liquefied
areas in lymphoma.
References
Fisher AJ, Paulson EK, Sheafor DH, et al: Small lymph
nodes of the abdomen, pelvis and retroperitonelllll:
Usefulness of sonographically guided biopsy. Radiology
1 997; 205 : 1 85- 1 90.
Jing BS: Diagnostic inuging of abdominal and pelvic
lymph nodes in lymphoma. Radiol Clin North A m
1 990;28:80 1 -83 1 .
Cross-Reference
Genitourinary Radiology: THE REQUISITES, P 1 8 1 .
Comment
The differential diagnosis of abdominal adenopathy is
similar to that of adenopathy elsewhere in the body.
Inflammatory and infectious conditions should be considered
because they are the most cornmon cause. Sarcoidosis
is a frequently forgotten cause of abdominal
adenopathy. Lymphoma and metastatic disease also must
be conSidered, especially when nodes are as large as the
ones shown in this case. Retroperitoneal and periportal
adenopathy is very nonspecific, but bulky adenopathy
in the mesentery is usually due to non-Hodgkin's lymphoma.
Abdominal adenopathy is often overlooked on sonography.
This is probably because enlarged nodes are usually
close to isoechoic when compared to the organs in
the abdomen. They must be recognized as rounded or
ovoid masses separate from the solid organs and the
bowel. In the retroperitoneum and mesentery, nodes are
best seen when the overlying structures are compressed
with transducer pressure. Compression is also critical
in performing ultrasound guided biopsies, which allows
for biopsy of even small nodes.

Front 110

lon g itudi n a l and tran sverse views of the right kidney. The left kidney
had a similar appearance.
1 . Describe the abnormality.
2. Is this a mild or severe form of the disease?
3. What are the three most common etiologies of this condition?
4. What would you expect to see on an abdominal radiograph?

Back 110

Stones I m pacted i n the G allbladder N eck
1 . Both patients have stones and/or sludge layering
into the dependent aspect of the gallbladder (GB).
In addition, they both have impacted stones at the
junction of the GB neck and cystic duct.
2. Contracted GB, extensive right upper quadrant
bowel gas, very small stones, obesity, patient
immobility and stones in the gallbladder neck can
cause false-negative results on an ultrasound scan.
3. Almost nothing can simulate a gallstone. Therefore,
the positive predictive value is close to 1 00%.
4. Cholescintigraphy is useful when the sonographic
findings are confUSing or indeterminant. It is
unlikely that cholescintigraphy would be useful in
these patients because an impacted stone is clearly
present in both.
Reference
Middleton WD: Right upper quadrant pain. In Bluth
EI, Benson C, Arger P, et al (eds): Tbe Practice of
Ultrasonography. New York, Thieme, 1 999, pp 3 - 1 6.
Cross-Reference
Ultrasound: THE REQUISITES, pp 38-40.
Comment
A gallstone is usually quite easy to identify as an echogeniC
focus contrasted in the anechoic background of
the intraluminal bile. However, when a stone is located
in the GB neck or the cystic duct, it is not surrounded
by bile and is not as obvious. In most individuals, the
neck is the most posterior portion of the GB, so it is
not uncommon for stones to rest in the neck in supine
patients. In most cases, stones can be moved out of the
neck by positioning the patient so that the neck is not
the most dependent aspect of the GB. This can be
accomplished in most patients by rolling the patient
into a left lateral decubitus or a prone pOSition. The left
lateral decubitus pOSition is especially beneficial because
the GB is generally easiest seen with patients in
this pOSition, while it can be difficult to see well with
patients in the prone position. Even when the GB is not
well seen in the prone pOSition, it is still useful to have
patients roll into that position and then roll back to a
left lateral decubitus position because stones may be
seen rolling from the fundus back into the GB body
with this maneuver. Another maneuver that may help is
to have the patient stand upright and, if necessary, bend
forward at the waist.
Despite these maneuvers, some stones in the GB
neck will not move. As might be expected, nonmobile
stones in the GB neck are one of the causes of a falsenegative
ultrasound. This situation occurs with obstructing
stones that are impacted in the neck or with stones
1 22
that are transiently trapped behind prominent junctional
folds between the GB neck and the cystic duct. To avoid
overlooking this variety of stone, it is inlportant to
care1i.llly look at the region of the gallbladder neck. A
variety of approaches can be used to image the GB
neck. Scanning from a subcostal approach through the
1i.mdus of the GB is often very use1i.il. Another approach
is to scan from a lateral intercostal space using the liver
as a window.

Front 111

lon g itudi n a l and tran sverse views of the right kidney. The left kidney
had a similar appearance.
1 . Describe the abnormality.
2. Is this a mild or severe form of the disease?
3. What are the three most common etiologies of this condition?
4. What would you expect to see on an abdominal radiograph?

Back 111

Medul lary N ephrocalci nosis
1 . Both views show increased echogenicity of the
medullary pyramids.
2. This is a mild case because the pyramids produce
no shadowing. The absence of shadowing indicates
that the extent of calcification is minimal.
3. MedulJary sponge kidney, hyperparathyroidism, and
distal renal tubular acidosis are the common causes
of medullary nephrocalcinosis.
4. Radiographs are normal with mild nephrocalcinosis.
In more advanced cases, radiographs show small
calcifications in the expected regions of the renal
pyramids.
Reference
Glazer GM, Callen PW; Filly RA: Medullary nephrocalcinosis:
Sonographic evaluation. AJR Am J RoentgenoI
1 982 ; 1 38:SS-S7.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 04- 1 OS.
Comment
Nephrocalcinosis refers to renal calcification outside of
the collecting system . Most commonly it occurs in the
medullary pyramids and is caused by hyperparathyroidism,
renal tubular acidosis, or medullary sponge disease.
Other, less common causes include milk alkali syndrome,
sarcoidosis, and hypervitaminosis D.
On sonography, the pyramids appear hyperechoic.
As the calcification progresses, shadowing is detected
in some of the pyramids. Continued progression results
in more pronounced shadowing from all of the pyramids.
Sonography appears to be unusually sensitive in
detection of medullary nephrocalcinosis. Sonographic
findings clearly precede radiographic changes and are
often more dramatic than the findings on CT. The best
way to detect medullary neplu'ocalcinosis is to get a
longitudinal view of the kidney just lateral to the renal
sinus. In this view, the echogenic pyramids can be seen
and are easier to distinguish from the echogenic renal
sinus fat.

Front 112

Pu lsed Doppler waveforms from two veins.
1 . Which waveform i s from a normal hepatic vein, and which i s from a peripheral systemic vein?
2. Why do the waveforms have a different appearance?
3. Identify ventricular systole, ventricular diastole, and atrial contraction on the first waveform.
4. What effect does a deep inspiration have on the hepatic vein waveform?

Back 112

Normal Hepatic Venous Waveform
1 . The triphasic pattern in the first waveform is
typical of a normal hepatic vein waveform. The
slow respiratory phasicity of the second waveform
is typical of a peripheral vein.
2. The hepatic veins are very close to the right atrium,
and the pulsatility of the right atrium is readily
transmitted into the hepatic veins. The peripheral
extremity veins are more remote from the right
atrium, and the pressure fluctuations are much
more blunted or are absent.
3. Ventricular systole is the larger, first pulse below
the base line. Ventricular diastole is the smaller,
second pulse below the base line. Atrial contraction
is the short pulse above the base line.
4. Deep inspiration causes some blunting of the
normal triphasic pattern. In some cases, it
eliminates all of the pulsatility.
Reference
Abu-Yousef MM: Normal and respiratory variation of the
hepatic and portal venous duplex Doppler waveforms
with simultaneous electrocardiographic correlation.
] Ultrasound Med 1 992; 1 1 : 263-268.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 9-2 1 .
Comment
Because the hepatic veins are so close to the right
atrium, the pressure fluctuations in the atrium are transmitted
back into the hepatic veins. This effect can be
seen in the hepatic venous waveform. During right atrial
contraction there is a short period where the blood
flow in the hepatic vein actually reverses and heads
back into the liver. This is seen as the short phase of
flow above the base line. As the right atrium relaxes
(corresponding to ventricular systole), blood flow rapidly
exits the liver and enters the atrium, producing
flow below the base line. As the atrium starts to fill up,
the flow out of the liver slows, and the waveform starts
to approach the base line. Then the tricuspid valve
opens (at the beginning of ventricular diastole), and the
right atrium starts to decompress into the right ventricle.
This leads to another period of rapid outflow from
the liver into the right atrium, resulting in a second
pulse of flow below the base line. Finally, the right
atrium starts to contract again, and the process repeats
itself. The end result is a triphasic pattern with one
retrograde pulse above the base line (during atrial contraction)
and two antegrade pulses below the base line.
The first antegrade pulse is usually the largest and occurs
during ventricular systole. The second antegrade
1 24
pulse is usually smaller and occurs during ventricular diastole.
The second waveform in this case Gune from a superficial
femoral vein. Because it is so far away from the
right atrium, the pulsatility related to the heart is lost. In
its place is mild phasicity related to respiratory changes.

Front 113

Transverse and longitudinal views of the pancreas.
1 . Is this a typical location for this lesion?
2. Is this lesion benign or malignant?
3. Would you consider another diagnosis if this patient were a man?
4. At what age is this lesion most frequently seen?

Back 113

M ucinous Macrocystic Pancreatic Neoplasm
1. Mucinous macro cystic neoplasms are usually
located in the body and tail of the pancreas. It is
unusual to see them in the head of the pancreas.
2. This lesion is malignant or potentially malignant.
3. Yes. Mucinous macrocystic neoplasms are seen
almost exclusively in women.
4. This lesion is most frequently seen in middle age.
Reference
Buetow PC, Rao P, Thompson LDR: From the archives of
the AFIP: Mucinous cystic neoplasms of the pancreas:
Radiologic-pathologic correlation. Radiograpbics 1 998;
1 8: 433-449.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 37- 1 39.
Comment
The macrocystic mucinous pancreatic neoplasm is seen
much more commonly in women than in men. They
are usually located in the body or more often in the tail
of the pancreas. The majority manifest in middle age.
Although some of these tumors have benign histologic
features, they should all be considered potentially malignant.
Some experts believe that this tumor is a variety
of mucin-producing pancreatic neoplasm where the abnormal
ductal epithelium originated in a peripheral side
branch and lost its communication with the main pancreatic
duct. Even when these tumors are malignant,
the prognosis is much better than it is for ductal adenocarcinoma
of the pancreas. In fact, complete surgical
resection results in up to 90% long-term survival.
Mucinous macrocystic tumors tend to be very large
and may be either unilocular or multilocular. Solid mural
nodules can occur and make the chance of frankly
malignant histology more likely. When the lesion is
multiloculated, the individual locules are usually larger
than 2 cm. Focal areas of calcification are seen in the
wall of the mass in less than 1 0% of patients. Unlike the
micro cystic pancreatic neoplasm, central calcification
is rare.

Front 114

Transverse grey-scale and power Doppler views of the testis.
1 . What are the major findings in this case?
2. Are these abnormalities most likely due to a neoplastic or nonneoplastic etiology?
3. Does the ag

Back 114

Testicular Abscess
1. The images show an avascular intra testicular mass,
a hydrocele, and increased testicular vascularity.
2. These abnormalities are most likely nonneoplastic.
Tumors would be expected to have some
detectable internal flow and would not produce
increased flow to the rest of the testis.
3. Tumors are less common in older men.
4. The most inlportant clinical information is whether
the lesion is palpable. Intratesticular lesions that
can be palpated are much more likely to be tumors.
Reference
Horstman WG: Scrotal imaging. Urol Clin North Am
1 997; 24:653-67 1 .
Cross-Reference
mtrasound: THE REQUISITES, pp 445 -446
Comment
A testicular tumor (especially maHgnant tumors bu t also
benign tumors) should always be considered when an
intratesticular lesion is seen on sonography. However,
there are many nonneoplastic conditions that can also
appear as an intra testicular mass and simulate a tumor.
Included in tllis list are hematomas, abscesses, infarctions,
contusions, necroSiS, inflammatory lesions, and
granulomatous diseases. There is so much overlap in
the grey-scale appearance of these conditions and tumors
that it is not possible to rely much on the greyscale
features.
On the other hand, Doppler findings can be useful
to a certain extent. Provided that appropriate transducers
are used and appropriate technical adjustments are
made to optimize detection of low blood flow, most
tumors have at least some detectable flow, and many
are hypervascular. Inflammatory lesions may also be
vascular, but most other nonneoplastic lesions are avascular.
This is true of fluid collections, such as hematomas
and abscesses, and also of infarctions, contusions,
and necrosis.
Findings on physical examination and other clinical
features can be very valuable in further defining the
etiology of intratesticular lesions. The most important
clinical information is whether the lesion is palpable or
not. Most nonneoplastic lesions are nonpalpable, and
most tumors are palpable. Clinical evidence of infection
or inflammation is clearly helpful in patients with orchitis
or an abscess. A history of trauma certainly would
lead one toward a diagnosis of hematoma or contusion,
whereas a llistory of tuberculosis or sarcoid would suggest
that an intra testicular abnormality was a granulomatous
lesion.
1 26
In the final management of intratesticular lesions,
surgery is usually performed if either the clinical or the
sonographic findings suggest a tumor. If the sonograpllic,
Doppler and clinical findings all suggest a nonneoplastic
condition, surgery can usually be avoided
and replaced with a series of follow-up sonograms to
determine whether the lesion responds to conservative
therapy in the expected manner.

Front 115

lon g itudinal g rey-scale view and transverse color Doppler view of the
left lobe of the liver.
1 . Is the structure indicated by the arrows normal?
2. Would a Doppler waveform demonstrate arterial or venous flow?
3. Is this seen commonly on ultrasound?
4. From where does this structure originate?

Back 115

Replaced Left Hepatic Artery
1 . The arrows indicate a replaced or accessory left
hepatic artery. This is a normal variant.
2. A Doppler waveform would show an arterial signal
with the flow directed into the liver.
3. Because the left lobe of the liver provides such a
convetlient window, it is usually very easy to see
the fissure for the ligamentum venOStilll. Because of
thiS, replaced left hepatic arteries are also very easy
to see. Careful evaluation of tIlis region will reveal
tIlis variant in approximately 1 5 % of patients.
4. Replaced/accessory left hepatic arteries arise from
the left gastric artery.
Reference
Lafortune M, Patriquin H: The hepatic artery: Studies
using Doppler sonography. mtrasound Q 1 999;
15( 1):9-26.
Cross-Reference
mtrasound: THE REQUISITES, pp 3 - 5 .
Comment
A number of common vascular variants may be found
in the upper abdomen. Variations in the arterial supply
to the liver are among the most common. Normally, the
conunon hepatic artery arises as a branch of the celiac
axis. After the takeoff of the gastroduodenal artery, the
conunon hepatic artery is referred to as the proper
hepatic artery. The proper hepatic artery supplies the
arterial flow to the liver via its right and left branches.
However, both the right and left hepatic artery may
arise from sites other than the proper hepatic artery.
The left hepatic artery occasionally arises from the
left gastric artery. In such cases, it enters the liver
tlu'ough the fissure for the ligamentum venosum. It then
travels to the origin of the umbilical segment of the left
portal vein and enters the left lobe adjacent to this vein.
It is rare to see any other vascular structures in the
fissure for the liganlentum venosum, but it is common
to see tllis arterial variant.

Front 116

longitudinal color Doppler view of the carotid bifurcatio n a n d a
transj ugular i ntrahepatic porto-systemic shunt. (See color pl ates.)
1 . Where is the artifact located in the first image?
2 . Where is the artifact located in the second image?
3. How can this artifact be distinguished from true flow reversal?
4. How can this artifact be eliminated?

Back 116

Aliasing
1 . The first image shows aliasing in the center of the
internal carotid artery.
2 . The second image shows severe aliasing throughout
the lumen of the stent.
3. With aliasing, the color conversion occurs from the
high frequency shifts on one side of the scale to
the high frequency shifts on the other side of the
scale. Tllis is shown on the first inlage as
conversion from light red to light blue. True flow
reversal occurs from the low frequency shifts. This
is shown on the first image at the periphery of the
internal carotid origin.
4. Aliasing can be eliminated or decreased by
increasing the Doppler angle, increasing the
Doppler scale, or decreasing the transmitted
frequency.
Reference
Middleton WD: Color Doppler unage optimization and
interpretation. Ultrasound Q 1 998 ; 1 4 : 1 94-208 .
Cross-Reference
Ultrasound: THE REQUISITES, P 474 .
Comment
Aliasing is a well-known artifact that occurs when the
Doppler sampliIlg rate (Le . , the pulse repetition frequency
or PRF) is less than twice the Doppler frequency
sllift. When aliaSing occurs on color Doppler inlages,
there is a wrap-around effect so that the color representing
the llighest positive frequency shift changes to the
color representing the highest negative frequency sllift,
or vice versa. This change in color assignment can be
distulguished from true flow reversal because the
change is between light color shades rather than between
dark color shades. When aliasing is severe, there
can be multiple wrap-arounds of the color assignment,
and tIlis can produce an appearance of random color
assignment that sinlulates noise or severe flow turbulence
(as seen in the TIPS shunt). Although aliasulg is
artifactual, when properly recognized, it can be useful
because it dramatically identifies areas of high frequency
sllifts, and these areas of high frequency shifts often
correspond to areas of high flow velOCity.
Aliasing can be dinlinished or elimiIlated by increasing
the PRE In most ulstances, the maximum PRF is
liInited by the depth of the vessel, because it takes a
finite amount of time to deliver the Doppler pulse to
the vessel and wait for the echo to return to the transducer
before the next pulse is transmitted. Another
means of decreasing or eliIninatulg aliasing is to decrease
the observed frequency sllift. This can be done
by manipulatulg the transducer so that the vessel is
scanned at a Doppler angle closer to 90 degrees or by
switching to a lower frequency transducer.

Front 117

Mag n ified color Doppler view and p u l sed Doppler waveform of the right
l obe of the l iver in two patients. (See color plates.)
1 . What is the abnormality common to both of these patients?
2 . Is it normal to see any pulsations in the portal vein?
3. Does the abnormality shown in this case occur most often in the right 01' in the left portal vein?
4. Is this abnormality seen early 01' late in the underlying disease process?

Back 117

Portal Vein F low Reversal
1 . The color Doppler view shows parallel vessels. The
only vessels that travel in a parallel fashion are the
hepatic arteries and portal veins. The different
color assigmnents indicate that flow in the artery
and vein are Ul opposite directions. The waveform
shows simultaneous arterial flow and venous flow
on different sides of the base liIle. Tllis also
indicates that flow is in different directions. In the
liver, flow Ul both vessels should be in the same
direction, that is, U1tO the liver. In tllis case the
portal venous flow is reversed.
2 . There are mild pulsations in the portal venous
signal . This is withul normal linlits. Severe portal
veUl pulsations uldicate right heart dysfunction.
3. A conunon portal systemic collateral in patients
with portal hypertension is the recanalized
umbilical vein, which is supplied by the left portal
veul. A conunon finding in these patients is
reversed right portal flow that crosses the portal
bifurcation and contributes to antegrade left portal
flow and ultimately to flow into the umbilical vein.
4. Reversal of portal venous flow is a late sign of
portal hypertension.
Reference
Ralls PW: Color Doppler sonography of the hepatic
artery and portal venous system. AJR Am J Roentgenol
1 990 ; 1 5 5 : 5 1 7 - 5 2 5 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 9 - 2 3 .
Comment
Under normal circumstances, portal venous blood flow
travels UltO the liver. With diffuse liver disease such as
cu-rhosis, the resistance to portal veUl flow increases.
Increased portal pressures then develop in an attempt
to mau1taul constant portal perfusion of the liver. As the
portal pressure rises, portal-systemic collaterals start to
develop. As the liver disease progresses, resistance to
flow U1Creases to the pOUlt that hepatic arterial flow
cannot effectively cross the sinusoidal bed of the liver.
At this pOUlt, hepatic artery flow is shunted into the
portal veUl system, and the portal vein flow reverses. In
essence, the portal vein becomes an outflow tract for
the liver. With advanced portal hypertension, portal
veUl flow reversal initially starts in the peripheral portal
veU1S. If the process progresses, flow reversal may start
to effect the central portal veins and even the main
portal vein.

Front 118

Standard and mag n ified tra n sverse views of the right lobe of the l iver.
1 . What is the abnormality?
2 . What is the differential diagnosis?
3 . What underlying abnormality would you suspect if tIlis patient were Asian?
4. Which test would be most useful in further management of tWs patient, CT, ultrasound guided biopsy,
or endoscopic retrograde cholangiopancreatography (ERCP)?

Back 118

I ntrahepatic Bile Duct Stones
1 . The first image shows a branching, hyperechoic
linear structure in the periphery of the right lobe.
The magnified unage shows a dilated intrahepatic
duct and three adjacent stones with slight
shadowing.
2. The differential diagnosis includes intrahepatic duct
stone, biliary air, and calcified intrahepatic arteries.
3. Oriental cholangiohepatitis (also known as
recurrent pyogenic cholangitis) would be
suspected.
4. ERCP would be the most helpful next test.
Reference
Kirby, CL, Horrow MM, Rosenberg HK, Oleaga ]A: US
case of the day: Oriental cholangiohepatitis. RadiogmjJhics
1 995; 1 5 : 1 503-1 506.
Cross-Reference
Ultrasound: THE REQUISITES, pp 6 1 -63.
Comment
Intrahepatic duct stones usuaUy occur Ul the setting of
abnormal bile ducts. The classic condition associated
with intrahepatic duct stones is recurrent pyogenic cholangitis,
also lmown as Oriental cholangiohepatitis. In
this disease, bile stasis is believed to cause infection,
which results in deconjugation of bile and precipitation
of calcium bilirubulate crystals that ultimately form multiple
intrallepatic pigmented stones. These stones are
soft (muddy) and may form a cast of the bile duct
lumen. When they shadow, the diagnosis is usually evident.
However, they may not produce enough acoustic
attenuation to cause shadowing, and thus they may be
confused with blood clots or tumors of the duct. Other
conditions that cause biliary stasis can result Ul stones
that form primarily in the ducts. Sclerosing cholangitis
and Caroli's disease are two examples.
One of the conditions easiest to mistake for intrahepatic
stones is biliary air. Both can appear as shadowing
echogenic material in the bile ducts. However, au· is
usuaUy more echogenic, more mobile, casts a dirtier
shadow, or produces a ring-down artifact. Intrahepatic
stones rarely are mobile and never cause a ring-down
artifact. It is important to realize that patients can have
both au· and stones in the bile ducts. If there is a
significant amount of pneumobilia, it may be impossible
to determine whether the intrahepatic ducts are dilated
and also if there are stones present. Calcified arteries
can also cause confusion. Visualization of more central
arterial calcification in the larger vessels can point to
the correct diagnosis.

Front 119

Views of the left mid abdome n .
1 . Describe the abnormality shown on these images.
2. What is the differential diagnosis?
3 . Is this abnormality more common in children or in adults?
4. Does color Doppler have a role in evaluating patients with this abnormality?

Back 119

I ntussusception
1 . A target-like lesion with multiple concentric rings.
This is a typical appearance for an intussusception.
2. The differential diagnOSis ulcludes bowel wall
thickening from any cause, feces in the colon,
U1tramural hematoma, or, potentially, a volvulus.
3. Intussusception is much more common in early
childhood than in adults.
4. Color Doppler can help because lack of detectable
blood flow predicts the need for surgery and
increases the likelihood of bowel wall necrosis.
Reference
Del-Pozo G, Albillos ]C, Tejodor D : Intussusception: US
findings with pathologic correlation: The crescent Ul
douglullIt sign. Radiology 1 996; 1 99:688-692.
Cross-Reference
Gastrointestinal Radiology: THE REQUISITES, pp 1 32 -
1 33 .
Comment
Intussusception represents the invagination of one loop
of bowel into another loop of bowel. The proxi.n1al
segment that enters the intussusception is called the
intussusceptum, and the distal segment that receives
the intussusceptum is called the intussuscipiens. A variety
of causes give rise to intussusception. In children,
they are most often idiopathic and located at the ileocolic
jlll1ction. In adults, they are often associated with
a lead mass (polyps, lipomas, metastases, lymphomas,
cancer), Meckel's diverticulum, or celiac disease. However,
the increased use of ultrasound and CT has led to
increased detection of transient idiopathic intussusceptions
in adults. In this case, a small bowel series was
performed two hours after the ultrasound, and the intussusception
was resolved and no mass was seen.
The sonographic appearance of an intussusception is
predictable. Three concentric layers of bowel wall result
in multiple concentric, hypoechoic, and echogenic
rUlgs. In many cases, the ultussuscepted mesentery can
be seen in the proxi.n1al aspect of the intussusception
as a slightly eccentric echogenic structure. The appearance
of an intussusception has been variously compared
to a target, a bull's eye, a doughnut, a pseudokidney,
and a sandwich.

Front 120

Tra nsverse tra nsabdomina l view of the bladder and sag ittal endorecta l
view of the prostate.
1 . Describe the abnormality.
2 . What is the differential diagnosis?
3. What type of cyst in this area is associated with congenital anomalies of the genitourinary system?
4. How often does prostate cancer have cystic components?

Back 120

Prostatic Cyst
1 . The transabdominal image shows a simpleappearing
cyst posterior to the bladder. The
endorectal view shows that the cyst is located in
the midline, has a teardrop shape, and arises from
the prostate.
2. The most likely diagnosis is a prostatic utricle cyst
or a mullerian duct cyst. An ejaculatory cyst is also
a consideration, although that type of cyst tends to
deviate more from the midline.
3. Seminal vesicle cysts are believed to arise from an
embryologic abnormality of the mesonephric duct
that can also lead to ipsilateral agenesis of the
kidney and vas deferens and ectopic ureteral
insertion. Utricle cysts can also be associated with
hypospadias, cryptorchidism, and renal agenesis.
4. Prostate cancer only rarely has significant cystic
components.
Reference
Ngheim HT, Kellman GM , Sandberg SA, Craig BM: Cystic
lesions of the prostate. Radiograpbics 1 990; 1 0:635-
650.
Cross-Reference
Ultrasound: THE REQUISITES, pp 461 -462.
Comment
A variety of cysts can occur within or adjacent to the
prostate. Utricle cysts and milllerian duct cysts appear
in the midline and originate within the prostate. Utricle
cysts are typically fairly small. Miillerian duct cysts may
become larger and extend above the prostate. It is
difficult to distinguish these cysts sonographically. Utricle
cysts communicate with the uretlu'a and can cause
postvoid dribbling.
Ejaculatory cysts occur near the midline along the
course of the ejaculatory duct. They may be congenital
or due to obstruction of the ejaculatory duct. They are
typically asymptomatic, although when they enlarge,
they can cause perineal pain, pain with ejaculation,
dysuria, and hematospermia. They contain spermatozoa,
so aspiration can help to distinguish them from other
prostatic cysts.
Cysts of the seminal vesicles are distinguishable from
prostatic cysts because they are located superior to the
prostate and are lateral to the midline. As mentioned
previously, they are associated with other genitourinary
anomalies. They are also associated with autosomal
dominant polycystic kidney disease. Dilatation of the
seminal vesicle can be confused with a seminal vesicle
cyst. Seminal vesicle dilatation can occur as a result of
obstruction of the seminal vesicle or ejaculatory duct
and can be due to benign prostatic hypertrophy or may
follow prostatic surgery.

Front 121

Views of the scrotum in two patients with the same a bnorm a l ity.
1 . What is the differential diagnosis?
2. What is the most likely diagnosis if these were boys with precocious puberty?
3. if these lesions are tumors, are they likely to be palpable?
4. if these lesions are inflammatory, are they likely to be palpable?

Back 121

Leyd ig Cell Tu mor
1 . Intratesticular lesions that are hypoechoic, round,
and well defined are usually tumors. Germ cell
tumors are most common. In the proper clinical
setting, lymphoma and metastases are
considerations. Primary benign stromal tumors are
much less common but should also be considered.
NOlmeoplastic lesions such as abscess, hematoma,
focal orchitiS, and granulomatous disease are also
possibilities that should be considered if the history
is appropriate.
2. Leydig cell tumors can manifest with precocious
puberty.
3 . Most testicular tumors are palpable. In tIlis case,
the smaller lesion was too small to feel.
4. Inflammatory conditions that cause focal testicular
lesions are usually not palpable.
Reference
Horstman WG, Haluszka MM, Burkhard TB: Management
of testicular masses incidentally discovered by ultrasound
. ] UmI 1 994; 1 5 1 : 1 263- 1 265.
Cross-Reference
Ultmsound: THE REQUISITES, pp 439-440.
Comment
Stromal cell tumors of the testis account for approximately
5% of testicular neoplasms. They may contain
Leydig, granulosa, thecal, or lutein cells. Ninety percent
of stromal cell tumors are histologically benign. The
majority of stromal cell neoplasms are Leydig cell tumors.
These occur most often between the ages of 20
and 50 years. Androgens, estrogens, or combinations of
both may be secreted by these tumors. Therefore, patients
may present with gynecomastia, precocious puberty,
impotence, and loss of libido.
Sonograpllically, stromal cell tumors are indistinguishable
from germ cell tumors. They tend to be homogeneous,
solid, and hypoechoic. Cystic areas and calciiications
are uncommon unless the tumor is large and has
undergone hemorrhage and/or necrosis. Like other testicular
tumors, they usually have detectable internal
blood flow and they are usually palpable unless they are
quite small. Interestingly, small stromal cell tumors are
the most common inCidental, nonpalpable lesion discovered
in patients being scanned for other reasons.

Front 122

Longitudinal views of the rig ht and l eft testes.
1 . What is the most likely explanation for the difference in appearance of the two testes in this patient?
2. What are two important complications of this condition?
3. How often is the condition bilateral?
4. Under what circumstances is this a surgical condition?

Back 122

U ndescended Testis
1 . The smaller testis with more overlying soft tissue is
tmdescended and located in the inguinal canal.
Obviously, making this diagnosis is much easier
when scanning the patient yourself, when you can
observe that the abnormal testis is not located in
the scrotum.
2. Infertility and development of malignant germ cell
tumors are two important complications.
3. Approximately 1 0% are bilateral .
4 . Surgery is usually performed if the condition
persists after 1 year of age or if a testicular tumor is
identified.
Reference
Horstman WG: Scrotal imaging. Urol Clin North Am
1 997; 24:653-67 1 .
Cross-Reference
Genitourinary Radiology: THE REQUISITES, pp 3 1 9-
320.
Comment
Undescended testes, also referred to as cryptorchid testes,
occur in approximately 4% of term infants and 30%
of premature infants. In premature babies, the testis will
usually descend into the scrotum by 3 months of age.
At 1 year of age, the incidence is about 1 % . Approximately
80% of undescended testes are located in the
inguinal region. Most of these are just distal to the
external inguinal ring, and the rest are in the inguinal
canal. Intra-abdominal testes are located in the retroperitoneum
anywhere along the path of testicular descent,
from the lower pole of the kidney to the more common
location near the internal inguinal ring.
Many undescended testes are histologically abnormal
and demonstrate altered spermatogenesis. This leads to
a high rate of infertility. They are also predisposed to
germ cell tumors of the testis, especially seminoma. The
risk of germ cell tumors in the cryptorchid testis is as
much as 40 times higher than in the normal testiS, and
intra-abdominal testes have an even higher risk of cancer
than intrainguinal testes. Additional complications
of tmdescended testes include torsion and inguinal hernias.
Given the likeWlood of eventual descent i.nto the
scrotLUll, undescended testes are usually not treated
until 1 year of age. Between ages 1 and 5, the risk of
cancer can be eliminated by performing orchiopexy.
Between the ages of 5 and 1 0 , the impact of orchiopexy
on the risk of cancer diminishes, so complete orchiectomy
is usually considered.
The tissue covering an undescended testis is almost
always thicker than normal scrotal tissue. This finding
can be a clue to the diagnosis even when the anatomic
1 34
location of the scans is tlknown. Intra-abdominal testes
are often located immediately adjacent to the external
iliac vessels, and this is another clue to the diagnosis.
In some cases, the echogenicity of an undescended
testis is heterogeneous, but a discrete mass is not seen.
In other cases, the depth of the testes and the small
size of the testis precludes adequate evaluation with
sonography. In both these situations, MlU may be helpful
for further evaluation.

Front 123

Longitudi nal g rey-sca le and color Doppler view of the right kidney.
1 . What is the sonographic abnormality seen in these images?
2 . If this patient had pyuria, what would be the most likely diagnosis?
3. If this patient had hematuria, what would be the most likely diagnosis?
4. If this patient had a history of trauma, what would be the most likely diagnosis?

Back 123

Renal Abscess
1 . A complex cystic lesion in the kidney.
2. Renal abscess.
3. Renal tumor, especially renal cell cancer.
4. Renal hematoma.
Reference
Baumgarten DA, Baumgarten BR: Imaging and radiologic
management of upper urinary tract infections. Urol
Clin North Am 1 997; 24: 545-569.
Cross-Reference
Ultrasound: THE REQUISITES, pp 99- 1 00.
Comment
This case illustrates the differential diagnosis of complex
fluid collections in the kidney. Given the nonspecific
appearance on ultrasound, lesions such as this require
careful correlation with the clinical history.
Renal abscesses occur most often as the result of
inadequate treatment of pyelonephritis. The typical situation
in which inlaging is requested is a patient with
pyeloneplu·itis who has not responded after 72 hours
of antibiotic treatment. Patients at increased risk for
abscess formation include those with obstructed collecting
systems, stones, diabetes, and a history of intravenous
drug abuse.
Sonographically, renal abscesses are usually solitary,
round, complex collections. They may have a visible,
thick wall. Depending on the amount of fluid and the
composition of the fluid, there may be detectable posterior
acoustic enhancement. When an abscess is well
walled off, low-level echoes may be seen diffusely
throughout the lesion or may settle to the dependent
portion of the lesion and form a fluid level. Occasionally
gas bubbles form and produce typical bright reflectors,
sometimes with ring-down artifacts. Although ultrasound
can detect most significant renal abscesses, contrast
enhanced CT is clearly superior and should be
considered when the ultrasound is negative and clinical
suspicion remains high.

Front 124

Color Doppler views of the co mmon carotid a rtery and the vertebral
a rtery. (See color plates.)
1 . On what is color coding based?
2. Why is the color in the periphery of the common carotid artery different than in the center of the
vessel?
3 . Why is the color in the normal vertebral artery different in the proximal and distal segments?
4. On what is the Doppler frequency shift: dependent?

Back 124

Changes in Color Shading
1. Color coding is based on the mean Doppler
fre quency shift.
2. The color variations in the common carotid artery
are due to differences in the flow velocity along the
wall of the vessel and in the center of the vessel.
3. The color changes in the vertebral artery are due to
changes in the direction of the vessel and resulting
changes in the Doppler angle.
4. The Doppler frequency is dependent on the
velocity, Doppler angle, transmitted frequency, and
speed of sound.
Reference
Middleton WD: Color Doppler image optimization and
interpretation. Ultrasound Q 1998; 14:194-208
Cross-Reference
Ultrasound: THE REQ UISITES, pp 464-470.
Comment
The Doppler equation, which fo llows, indicates that the
Doppler frequency shift is proportional to the blood
flow velOCity:
Fd = Ft X V X cos8 X 11C X 2
where, Fd = Doppler fre quency shift, Ft = transmitted
Doppler fre quency, V = velocity of blood flow, 8 =
angle between the transmitted Doppler pulse and the
direction of blood flow, and C = speed of sound.
Therefore , higher flow velocities produce higher frequency
shifts and are assigned lighter color shades. In
situations where the blood vessel is straight and the
orientation of the Doppler pulse is constant, the primary
color assignment is usually constant tlu'oughout
the vessel, and any variation in color shading indicates
a change in velocity.
The Doppler equation also indicates that the £i'equency
shift is proportional to the cosine of 8. Because
of this, the Doppler fre quency shift is maximal for a
given velocity when the direction of the Doppler pulse
is parallel to the direction of the flow velocity (8 = 0°)
because the cosine of 0 degrees is 1. When the Doppler
pulse and the flow velocity are oriented perpendicular
to each other (8 = 90°), the cosine of 90° is 0, and
there is Httle, if any, detectable Doppler shift. Because
of tlus angle effect, vessels that have a m1iform flow
ve locity may vary in their color shading owing to
changes in the Doppler angle. Tlus situation arises fr equently
with curving vessels. Likewise, the color assignment
and color shade may change when the direction
of the Doppler pulse changes, as with sector or curvilinear
probes.

Front 125

Long itu d i nal color Doppler views of the left hepatic lobe a n d left hepatic
vei n . (See color plates.)
1 . What causes the extravascular color assignment on the first image?
2 . How has the extravascular color assignment been eliminated on the second image?
3. What is another way to eliminate artifactual color assignment that obscures background tissues?
4. Is it possible to suppress Doppler signals from flowing blood?

Back 125

Use of the Wa ll Filter to Suppress
Tissue Motion
1. The extravascular color assignment is caused by
tissue motion related to cardiac pulsations.
2. The wall filter has been increased. Tlus is shown on
the display of teclulical parameters as F-VLow
(filter very low) and F-High (filter hlgh).
3. Adjust the color priority.
4. Improper adjustment of both the wall filter and the
color priority can suppress Doppler signals from
intravascular blood flow as well as from moving soft
tissues.
Reference
Middleton WD: Color Doppler image optimization and
interpretation. Ultraso und Q 1998; 14: 194-208.
Cross-Reference
Ultras ound: THE REQUISITES, pp 464-470.
Comment
Doppler techniques are intended to detect moving
blood cells in the vascular system. Since moving reflectors
produce a Doppler sllift, blood that is flowing in a
sufficient quantity and at a sufficient velocity can be
detected with Doppler tecluuques. Unfortunately, tissues
in the body other than blood also move to some
degree. In this case, cardiac contractions have resulted
in movement of the left hepatic lobe. This movement
has produced enough of a Doppler sllift to be detected
by the ultrasound equipment, and thus, color has been
assigned to nonvascular portions of the left lobe. Respiratory
motion, bowel peristalsis, fe tal movement, and
muscular contraction are other examples of nonvascular
motion that can produce unwanted Doppler signals. In
the vascular system, movement of the vessel wall can
also produce a Doppler signal.
In situations such as those just described, eliminating
unwanted signals or artifactual signals is more important
than detecting low-volume or low-velocity flow. One
control that is intended to filter out fre quency sllifts
arising from pulsating vessel walls or moving soft tissues
is called the wall filter, a high pass filter that allows
fre quency shifts above a certain level to be displayed
wl1ile fr equency shifts below that level are not displayed.
Use of tlus filter can produce the desired effect
of reducing or eliminating tissue motion. It is important
to recogluze however, that if the wall filter is adjusted
improp erly, it can also filter out true low-level blood
flow. Therefore, in situations where there is little tissue
motion and not much background noise, the wall filter
can be lowered to ensure that low-velocity or lowvolume
flow is detected.

Front 126

Transverse view of the pa ncreatic body and longitudinal view
of the pancreatic head in two patients.
1 . What are the two tumors that should be considered first in your diff erential diagnosis?
2. Which of these tumors is more likely to contain calcifications?
3 . Which of these tumors is hypovascular?
4. Which of these tumors most often obstructs the pancreatic duct?

Back 126

Islet Cell Tu mor of the Pancreas
1 . Adenocarcinoma and islet cell tumors are the most
likely possibilities.
2. Islet cell tumor is more likely to contain
calcifications.
3. Adenocarcinoma is hypovascular.
4. Adenocarcinoma more commonly obstructs the
duct.
Reference
Beutow PC, Miller DL, Parrino Tv, Buck JL: Islet cell
tumors of the pancreas: Clinical radiologic and pathologic
correlation in diagnosis and localization. Radiographies
1 997; 17:453-47 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 36- 1 38 .
Conunent
Islet cell tumors are much less common than ductal
adenocarcinoma of the pancreas. The most common
type of islet cell tumor is the insulinoma. In approximately
90% of cases this occurs as a solitary lesion.
Approximately 1 0% of cases are multiple, and 1 0% are
malignant. Owing to hypersecretion of insulin, patients
usually present at an early stage, when the tlUnor is
small (typically 1 . 5 cm or less), with symptoms of hypoglycemia
such as headaches, fainting, fatigue, drowsiness,
seizures, and personality changes.
Gastrinomas are the next most common type of islet
cell tumor. They differ from insulinomas in that they
are most often malignant, they are frequently multiple,
and they occur most often in the head of the pancreas
and the wall of the duodenum. They are the most
common islet cell tumor in patients with multiple endorine
neoplasia (MEN) type I syndrome. Other rare
islet cell tumors include glucagonomas, vipomas, somatostatinomas,
and nonfunctioning tumors. Nonfunctioning
tumors manifest later and are therefore more
likely to be large and often contain cystic areas of
necrosis as well as calcification.
On sonography, functioning islet cell tumors usually
appear as small, well-marginated, homogeneous, hypoechoic
lesions. Central calcification or cystic changes
can occur and increase the likelihood of malignancy.
The lesions are usuaUy hypervascular on contrast enhal1Ced
CT or angiography, but this vascularity is usually
not detectable on transabdominal Doppler. Although
the imaging features overlap with those of ductal adenocarcinoma,
islet cell tumors are usually smaller and better
defined and lack the tendency to encase adjacent
arteries and obstruct the pancreatic and bile ducts.
Liver metastases from islet ceU cancers are sometimes
hyperechoic, and this is unusual for metastases from
adenocarcinoma of the pancreas.

Front 127

Pulsed Doppler waveform with two s pectral measurements.
1 . What is being measured in the first unage?
2 . Is this measurement dependent on the Doppler angle?
3 . What is being measured in the second image?
4 . Is this measurement dependent on the Doppler angle?

Back 127

Spectral Doppler Measurements
1 . The first measmement is the resistive index (RI).
2. The RI is independent of the Doppler angle.
3. The second measurement is the systolic
acceleration.
4 . The acceleration is dependent on the Doppler
angle.
Reference
Nelson TR, Pretorius DH: The Doppler Signal: Where
does it come from and what does it mean? AJR A m
J Roentgenol I 988; 1 5 1 :439-447.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-470.
Conunent
A number of measurements are used to analyze arterial
waveforms. The most common is the resistive index
(RI), defined as:
RI = 1 - (DIS) = (S - D)/S
where S is the peak systolic velocity (or frequency shift)
and D is the end diastolic velOCity (or frequency shift).
The RI goes up when resistance to flow goes up. When
there is no diastolic flow, the RI is 1 . Because the
calculation depends only on the ratio of systolic to
diastolic flow, it is independent of Doppler angle. Parenchymal
organs should normally have a resistive index of
less than 0.7.
Another common measurement is the pulsatility index,
defined as:
PI = (S - D)/M
where M is the mean flow velOCity throughout the
cardiac cycle. The pulsatility index is probably a truer
indication of vascular resistance than the resistive index,
but because it is harder to measure, it has not gained
widespread use. Like the RI, pulsatility index is independent
of Doppler angle.
In addition to these measurements of vascular resistance,
measurements of systolic upstroke are also becoming
more widely used as a means of detecting proximal
arterial stenosis. The early systolic acceleration is
one such parameter. It is obtained by measuring the
slope (change in velocity divided by change in time) of
the early systolic upstroke. Unlike the RI and the pulsatility
index, systolic acceleration requires determination
of an absolute difference in velocities and thus must be
calculated from an angle-con-ected velOCity waveform.

Front 128

longitudinal and transverse views of the shoulder.
1 . Is the abnormality shown in these images a common or uncommon cause of shoulder pain?
2 . Is this patient likely to be younger than 40 years old?
3. What tendon(s) is/are involved?
4. What is the sensitivity of ultrasound in establishing this diagnosis?

Back 128

Full Thickness Rotator Cuff Tear
1. Rotator cuff disorders are the most common cause
of shoulder pain and dysfunction.
2. Full thickness rotator cuff tears are uncommon in
patients younger than 40 years old, unless there is a
history of unusual athletic activity.
3 . The transverse view shows that the tear is located
1 2 mm from the biceps tendon. This is in the
territory of the supraspinatus.
4. Ultrasound is capable of detecting close to 1 00% of
full thickness rotator cuff tears.
Reference
Teefey SA, Middleton WD, Yamaguchi K: Shoulder sonography:
State of the art. Radiol Clin Nortb Am
1 999; 37:767-786.
Cross-Reference
Ultrasound: THE REQUISITES, pp 455-457.
Comment
Full thickness rotator cuff tears refer to tears that extend
from the deep surface of the cuff to the superficial
surface of the cuff. They may be small and only involve
a tiny region of a single tendon, or they may be large
and involve multiple tendons. The majority of tears
originate at the site of insertion of the supraspinatus
tendon to the greater tuberoSity. From there, they may
extend posteriorly to involve the infraspinatus, extend
medially to involve the more proximal supraspinatus, or
extend in both directions. The subscapularis tendon
may also be involved with massive full thickness rotator
cuff tears. However, it is rare to have an isolated tear of
the subscapularis tendon in the absence of a prior anterior
shoulder dislocation or a dislocated biceps tendon.
The sonographic appearance of full thickness rotator
cuff tears depends on whether there is a significant
amount of fluid in the jOint. When fluid is present, the
tear appears as a fluid-filled defect. TIns type of tear is
referred to as a wet tear, and these are generally very
easy to identify, and the appearance is easy to understand.
Such is the case in the images shown here.
Once a full tlnckness tear has been identified, it is
important to determine wInch tendons are involved. 1£
the tear just involves the first l .5 cm of cuff behind the
biceps tendon, then it is isolated to the supraspinatus.
1£ it extends to involve the cuff more than 1 . 5 cm behind
the biceps, then the infraspinatus is also involved. These
measurements are made on the short axis (transverse)
views. The degree of retraction of the cuff from the
greater tuberosity is measured on the long axis (longitudinal)
view.

Front 129

lon gitudinal and transverse views of the l iver in the region of the portal
vein bifu rcation.
1 . What comes to mind when you see an echogenic lesion anywhere in the body?
2 . What is the differential diagnosis for hyperechoic liver masses?
3. What is most characteristic about this lesion?
4. If necessary, how would you confirm the diagnosis?

Back 129

Focal Fatty I nfi ltration of the Liver
1 . Things that cause increased echogenicity in a lesion
include air, calcification, fat (usually mixed with soft
tissue or liquid), and multiple interfaces.
2. The basic differential diagnosis for hyperechoic liver
masses includes hemangioma, focal fat, metastatic
disease, and hepatocellular cancer. Adenoma and
focal nodular hyperplasia (FNH) are less likely
possibilities. Gas-containing abscesses are a
consideration in the proper clinical setting.
3. The characteristic features in tIns case of focal fat
infiltration are the typical location in the preportal
region of the liver and the nonspherical shape.
4. Fatty infiltration of the liver can be confirmed with
a high degree of certainty with MRI.
Reference
Yosllikawa ], Matsui 0, Takashima T, et aI: Focal fatty
change of the liver adjacent to the falciform ligament:
CT and sonographic findings in five surgically confirmed
cases. AJR Am J Roentgenol 1 987 ; 1 49 : 49 1 -
494.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 6-20.
Comment
Focal fatty infiltration of the liver is a relatively common
condition that produces areas of increased echogenicity
in the hepatic parenchyma. It may be multifocal or
isolated. When it is multifocal, it is typically geograplnc
in shape and produces no mass effect on adjacent structures.
When it is solitary, it usually localizes to the
preportal portion of the liver (as in tlns case), or to the
anterior aspect of the left hepatic lobe adjacent to the
ligamentum teres. Nonspherical echogenic lesions in
these locations require no further workup .
In addition to these typical appearances, fatty infiltration
occasionally looks very nodular and localizes to
nonspecific areas of the liver. In such cases, the diagnosis
cannot be made by sonography. MRI with chenlical
shift imaging, using in- and out-of-phase (opposed
phase) sequences, can establish a confident diagnosis
of fatty infiltration in most of these cases.

Front 130

Transverse color Doppler view of the g roin and pulsed Doppler
wavefo rms from the profunda femora l artery, superficial femoral a rtery,
and the femoral vei n . (See color pl ates.)
1 . Describe the important findings.
2 . Is this abnormality seen most often above or below the femoral bifurcation?
3. What are the typical grey-scale findings in this condition?
4. How do these patients usually present clinically?

Back 130

Femoral Arteriovenous Fistu la
1. The color Doppler views show perivascular tissue
vibration centered over the femoral vein. The
profunda femoral artery waveform shows a normal
waveform for an extremity artery. The superficial
femoral artery waveform shows an abnormally high
level of diastolic flow. The femoral vein shows an
arterialized waveform with a turbulent appearance.
These findings are all typical of a fistula between
the superficial femoral artery and the femoral vein.
2 . Arteriovenus fistula CAVF) is almost always located
below the femoral bifurcation.
3. It is very unusual to see any grey-scale changes
associated with AVFs. When AVFs are chronic and
large, there may be enlarged tortuous vessels
leading to and exiting from the fistula.
4. Patients with AVFs usually come to attention when
a bruit is detected following a femoral puncture.
AVFs may also be detected during the evaluation of
postcatheterization pain and swelling.
Reference
Middleton WD: Duplex and color Doppler sonography
of postcatheterization arteriovenous fistulas. Semin
Inte1'v RadioI 1 990;7 : 1 9 2 - 1 97.
Cross-Reference
Ultrasound: THE REQUISITES, pp 481 -483 .
Conunent
Like pseudoaneurysms, AVFs have become more common
since the use of larger catheters and anticoagulation
for vascular interventional procedures. They rarely
cause symptoms, although large fistulas can potentially
cause high output stress on the heart or can cause
ischemic symptoms in the lower extremity. They are
rarely located below the femoral bifurcation because at
that level the femoral artery and vein are side by side,
and it is difficult to puncture the artery and the vein
simultaneously. On the other hand, below the bifurcation
the femoral vein starts to travel behind the artery,
so that it becomes easier to puncture both vessels simultaneously.
In addition, a branch of the femoral vein
frequently travels right between the superficial femoral
artery and the profunda artery, and this can be the vein
that is involved in the fistula.
Unlike pseudoaneurysms, AVFs essentially exhibit no
grey-scale changes. Therefore, the hemodynamic
changes that are detectable with Doppler are the only
way to make the diagnosis. The most dramatic change
seen on color Doppler is the perivascular tissue vibration
caused by the turbulent blood flow. This is essentially
the color Doppler equivalent of a thrill, and the
1 42
typical mixture of random red and blue color assignment
is well shown in tins case. Although tins can be
seen with arterial stenoses, it is usually much more
pronounced with AVFs. Another hemodynamic change
in tile artery is related to the bypass of the high resistance
arterial bed afforded by the direct communication
with the vein. Therefore, the arterial waveform changes
from the typical, high-reSistance, triphasic pattern to a
low-resistance pattern with more diastolic flow. On
color Doppler, continuous flow is seen in the artery
immediately adjacent to the fistula, while no flow is
seen during diastole in the segments of the artery that
are not close to the fistula. On the venous side, the jet
of arterial flow entering the compliant vein causes a
marked flow disturbance in the vein. Tins is seen as a
haphazard arrangement of intraluminal color and as a
very distorted venous waveform. In some cases, like the
one shown here, an arterial pattern can be seen in the
venous waveform. Finally, it is sometimes possible to
actually visualize the tract that connects the artery and
the vein on color Doppler. Even when the communication
is not seen, the localized hemodynamic changes
just described provide convincing evidence that an AVF
is present.

Front 131

Views of the rig ht u p per q u a d rant a n d the l iver i n two patients.
1. Do the bright lines indicated by the arrows correspond to an anatomic structure?
2. What is the etiology?
3. What is the most common cause of this finding?
4. Should you be concerned if you saw this adjacent to the bile duct in a patient 3 months after a
cholecystectomy?

Back 131

Ring-down Artifact
1 . The lines are nonanatomic. They represent artifacts
caused by ring-down.
2. The sound pulse causes something in the body to
resonate. Like a tuning fork, the resonating object
transmits sound back to the transducer. The
returning sound is interpreted as coming from
deeper tissues, and a bright line is formed deep to
the resonating structure.
3. Gas bubbles are the most common cause of ringdown
artifact.
4. Ring-down artifact can also be produced by metallic
objects such as surgical clips, so it is commonly
seen following cholecystectomy and should not
arouse concern.
Reference
Middleton WD: Ultrasound artifacts. In Siegel MJ (ed):
Pediatric Sonography, 2nd ed. New York, Raven
Press, 1 994.
Cross-Reference
Ultrasound: THE REQUISITES, P 63.
Comment
Ring-down is one of the most conspicuous ultrasound
artifacts, and when it is recognized and properly interpreted,
it can greatly assist in certain diagnoses. This is
because ring-down artifact occurs most frequently as a
result of gas. When a sound pulse interacts with gas
bubbles, it excites the fluid that is trapped between the
bubbles. This causes the fluid to resonate, or ring, in a
malmer analogous to hitting a tuning fork with a hammer.
Although gas is the most common cause of ringdown,
metallic objects, such as surgical clips, hardware,
or foreign bodies can also produce tIlis artifact.
Because the ringing starts after the sound pulse arrives
at the gas, the sound produced by the ringing
follows the returning echo back to the transducer. Tllis
constant stream of sound returning to the transducer is
interpreted as arising from reflectors deep to the gas.
Therefore, a continuous set of echoes is written on the
image deep to the gas. This produces the bright line
that is called a ring-down artifact. As is demonstrated in
this case, the linear artifact is oriented parallel to the
scan lines on the unage.
In certain clinical situations, it is very useful to know
that gas is present. For ulstance, a complex fluid collection
could be many tIlings, but if gas is present, the
likelihood of an abscess becomes very high. Another
example is a highly echogellic gallbladder wall with
shadowing. Tllis could be a porcelain gallbladder, but if
air is identified due to a ring-down artifact, then a
diagnosis of emphysematous cholecystitis should be
made. Therefore, it is important to look for and recognize
ring-down artifact when it is present.

Front 132

Views of the scrotu m in two patients.
1. What are the two most reasonable potential diagnoses in these patients?
2. Is it possible to tell the difference with ultrasound?
3. What are the most common causes for these conditions?
4. Do these conditions typically cross the midline?

Back 132

Complex Hydroceles
1 . Pyocele and hematocele are the most reasonable
diagnoses.
2. In most cases, it is very difficult to distinguish a
pyocele from a hematocele.
3 . Epididymitis is the most common cause of pyocele.
Trauma is the most common cause of hematocele.
4. Hydroceles, pyoceles, and hematoceles are confined
to one side of the scrotum by the median raphe.
Although they can occur bilaterally, they do not
cross the midline.
Reference
Feld R, Middleton WD: Recent advances in sonography
of the testis and scrotum. Radiol Clin North A m
1 992;30: 1033- 105 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 446-448.
Comment
The first thing to consider when analyzing fluid collections
in the scrotum is to decide if they are in the testis
or outside of the testis. If they are outside of the testis,
one should then decide if they are in the sac formed by
the tunica vaginalis or within the scrotal wall. In the
two unages shown Ul this case, the fluid is in contact
with the testis and is crescent-shaped. This is typical
of any fluid withul the tunica vaginalis. The internal
septations and the low-level echoes indicate that these
are not sunple hydroceles. As elsewhere in the body,
the presence of complex fluid in tile scrotum itlitially
raises the possibility of a hemorrhagic collection or an
ulfected collection. Few ways exist to distulguish the
two on ultrasound. If the collection contains very bright
reflectors with ring-down artifacts, then gas should be
diagnosed, and the presence of gas indicates either
ulfection with a gas-forming organism, communication
with a gas-contai.tling viscus, or some type of prior
instrumentation. Infected fluid may also incite an inflammatory
reaction in the surrounding tissues that can
be recognized on color Doppler as hyperemia. However,
once a complex fluid collection is seen in the scrotal
sac, clinical features are required to help distinguish
blood from pus.

Front 133

Views of the right and left testis.
1 . Where exactly are these bright reflectors located?
2 . How is this condition graded?
3. Does this patient require further workup or surgery?
4 . Is this condition usually unilateral or bilateral?

Back 133

Classic Testicu lar M icrol ithiasis
1. The calcifications are located in the lumen of the
seminiferous tubules.
2. Microlithiasis is classified as classic if it is possible
to see five or more microliths on at least one view
of the testis. It is classified as limited if all views of
the testis show fewer than five microliths.
3. Data from the second reference below indicates
that regular follow-up ultrasounds are low yield for
detecting tumors. It probably makes more sense to
do regular self-examinations and annual physical
examinations, and reserve sonography for cases that
develop a palpable abnormality.
4. Microlithiasis is usually bilateral.
References
Backus ML, Mack LA, Middleton WD, et al: Testicular
microlithiasis: Imaging appearances and pathologic
correlation. Radiology 1 994; 192:78 1 -785 .
Bennett HF, Middleton WD, Bullock AF, Teetey SA: Testicular
microlithiasis. US follow-up. Radiology 200 1 ;
2 1 8 : 359-363.
Cross-Reference
mtmsound: THE REQUISITES, pp 443-444.
Comment
Testicular microlithiasis refers to laminated concretions
that are located within the lumen of the seminiferous
tubules. Microlithiasis has been reported to be associated
with a number of abnormalities, the most in1-
portant of which is germ cell tumor of the testis. Although
the original report found that 40% of patients
with microlithiasis had a tumor, it is now clear that
significantly fewer patients with microlithiasis have a
coexistent tumor.
In addition to the coexistence of tumors and microlithiasis
at the time of the initial ultrasound, several case
reports have doclUnented the subsequent development
of a germ cell tumor in patients who had sonographically
documented microlithiasis but no tumor on the
initial sonogram. These reports have raised concern that
microlithiasis may be a premalignant condition in some
individuals. For this reason, it is now common practice
to recommend annual sonographic follow-up in patients
with microlithiasis. As indicated in the second reference
cited in this case, we have found that the yield of followup
sonograms is extremely low. Therefore, our current
approach is to recommend careful regular self-examinations,
annual examinations by a physician, and periodic
sonograms only when a palpable abnormality develops.
One unusual situation that occasionally arises is the
patient who has a tumor in one testis and bilateral
microlithiasis. In these patients, there is a significant
1 46
increased risk o f intratubular germ cell neoplasia i n the
contralateral testis. Since intratubular germ cell neoplasia
frequently progresses to a macroscopic tumor, we
recommend that the contralateral testis be explored
and biopsied at the time of the orchiectomy for the
ipsilateral tumor.

Front 134

Two views of the right kid ney.
1 . What is the primary differential diagnosis for this renal lesion?
2. What is the management of this type of lesion?
3. Is percutaneous biopsy valuable?
4. Would knowing the patient's gender help in favoring one diagnosis over the other?

Back 134

M u ltilocu lar Cystic Nephroma
1 . Cystic renal cell carcinoma and multilocular cystic
nephroma are the primary considerations in a
multiloculated cystic renal mass.
2. Lesions with this appearance require surgical
excision because of the possibility of cystic renal
cell cancer.
3. Percutaneous biopsy is not recommended because a
negative biopsy result does not exclude a renal cell
carcinoma.
4. In adults, multilocular cystic nephroma is much less
common in men.
Reference
Agrons GA, Wagner B], Davidson A], Suarez ES: From
the archives of the AFIP: Multilocular cystic renal
tumor in children: Radiologic-pathologic correlation.
Radiographies 1 995 ; 1 5:653-669.
Cross-Reference
mtrasound: THE REQUISITES, pp 96-97.
Comment
Multilocular cystiC nephroma is considered by most to
be a benign renal neoplasm. As the name implies, it
consists of multiple cystic spaces that do not communicate
with each other or with the renal collecting system.
The cysts are epithelium-lined and separated by fibrous
septations. The lesion is usually well encapsulated. The
condition tends to affect young boys (typically 3 months
to 4 years of age) and adult women (over age 30).
Multilocular cystic nephroma has no malignant potential,
and if a confident diagnosis could be made
with ultrasound or a combination of imaging tests, then
surgery would not be necessary. Unfortunately, there is
overlap in the appearance of some varieties of cystic
renal cell carcinoma and multilocular cystic nephroma.
Percutaneous biopsies are not indicated because a negative
biopsy result does not exclude the possibility of
renal cell cancer. Because it is not possible to confidently
distinguish these leSions, surgery is usually necessary.

Front 135

Pu lsed Doppler waveforms from two a rteries.
1. Would you characterize these waveforms as high or low resistance?
2. What is the difference in these two waveforms?
3. Which of these waveforms is likely to have come from a normal internal carotid artery, and which is
likely to have come from a normal arcuate artery in the kidney?
4. What parameter is displayed on the vertical axis?

Back 135

Low Resistance Arterial Waveforms with
and without Spectral Broadening
1 . Both waveforms have low resistance characteristics.
2. The second waveform has signal that extends from
the base line all the way to the maximum. The first
waveform has a clean window under the signal.
3. The clean signal is typical of a larger superficial
artery, such as the internal carotid artery, and the
broadened signal is typical of a smaller, deeper
artery, such as the renal arcuate artery.
4. The vertical axis represents the Doppler frequency
shift. If the direction of blood flow is known, a
Doppler angle can be determined, and the
frequency shift information can be converted to
velocity information.
Reference
Nelson TR, Pretorius DH: The Doppler signal: Where
does it come from and what does it mean? AJR A m
J Roentgenol 1 988; 1 5 1 :439-447.
Cross-Reference
Ultrasound: THE REQUISITES, pp 464-470.
Comment
Both of the waveforms shown demonstrate relatively
broad systolic peaks, slow systolic deceleration into
diastole, and weli-maintained diastolic flow throughout
the cardiac cycle. This is typical of an artery that supplies
a vascular territory with a low resistance to blood
flow. The solid parenchymal organs of the body are the
structures that have low resistance flow. Therefore, this
type of waveform could be seen from the brain, kidney,
liver, spleen, testes, and so forth.
The difference in the two waveforms is the continuous
signal extending from the base line to the maximum
for the renal arcuate artery. TI1is occurs because a broad
range of velocities is being sampled, which produces a
broad range of frequency shifts. This phenomenon is
known as spectral broadening and was originally used as
a sign of disordered or turbulent blood flow. However,
spectral broadening is also typical of small parenchymal
vessels. In the internal carotid artery, the range of frequency
sllifts is much narrower and concentrated near
the maxin1Um, so that there is a clear window between
the signal and the base line. TI1is difference is at least
partially related to the relative size of the vessel and the
size of the sample volume. In a small vessel, the slow
flow at the edge of the vessel wall and the faster flow
in the center of the lumen are being sampled simultaneously.
In a larger vessel only the faster flow in the center
is being sampled. In addition to large sample volumes,
11igh Doppler gain and high power outputs can also
produce spectral broadening in normal vessels

Front 136

Two views of the liver.
1 . Describe the abnormality indicated by the arrows.
2. Is this condition seen more often on ultrasound or on CT?
3. Where else is this abnormality typically seen?
4. What can be done to help increase diagnostic confidence?

Back 136

Fatty I nfiltration with Focal Sparing
1. Both images show an area of apparently decreased
echogel1icity in the liver parenchyma immediately
adjacent to the gallbladder. This is typical of focal
sparing in an otherwise diffusely fatty liver.
2. Ultrasotmd is more sensitive than CT for fatty
infiltration. Therefore, focal fatty sparing is seen
more often on ultrasound.
3. Fatty sparing typically occurs around the gallbladder
and anterior to the portal bifurcation.
4. To further confirm fatty sparing, it is useful to
compare the liver to the right kidney and pancreas
in order to confirm that the rest of the liver is fattyinfiltrated.
Reference
Wl1ite EM, Simeone JF, Mueller PR, et al: Focal periportal
sparing in hepatic fatty infiltration: A cause of hepatic
pseudomass on ultrasound. Radiology 1 987 ; 1 62 : 57-
59.
Cross-Reference
Ultrasound: THE REQUISITES, pp 16- 1 8 .
Comment
Fatty infiltration of the liver is usually a diffuse process.
However, it is relatively common to have small regions
of liver parenchyma that are spared. This is probably
most common in the liver parenchyma immediately adjacent
to the gallbladder. It is also very common in segment
4 of the liver, immediately anterior to the portal
bifurcation.
The problem with fatty sparing is that it is easy to
assume that the echo genic fatty-infiltrated liver is normal
and the less echogenic spared area is abnormal. Wl1en
this happens, the spared areas can be confused with a
number of abnormalities that are hypoechoic, such as
neoplasms, infarcts, infections, and so forth. Recognition
that the liver is fatty-infiltrated is extremely helpful.
In addition, several clues can help to avoid tl1is p itfall.
Fatty sparing produces no mass effect, is not spherical,
is usually in typical locations, and often changes dramatically
on short-term follow-up.

Front 137

Tra nsverse views of the pancreas i n two patients with d iffe rent
man ifestations of the same d isease.
1 . Describe the abnormal findings?
2. What might be seen on endoscopic retrograde cholangiopancreatography (ERCP)?
3. Are these patients likely to have gallstones?
4. What would your diagnosis be if you saw a pancreatic cyst in these patients?

Back 137

Chronic Pancreatitis
1 . The first image shows diffuse punctate calcifications
in the pancreas. The second image shows irregular
dilatation of the pancreatic duct and parenchymal
atrophy. These abnormalities are all consistent with
chronic pancreatitis.
2 . ERCP would show irregular dilatation and short
strictures of the pancreatic duct, with ectatic side
branches and possibly filling defects due to
intraductal concretions.
3. Chronic calcific pancreatitis is caused by alcohol
abuse, not by gallstones.
4 . A pseudocyst. Approximately 25% to 40% of
patients with chronic pancreatitis develop
pseudocysts.
Reference
Taylor Al, Bohorfoush AG (eds): Pancreatic duct in inflammation
of the pancreas. In Interpretation of
ERCP with Associated Digital Imaging Correlation.
Philadelphia, Lippincott-Raven, 1 997, pp 2 3 1 -260.
Cross-Reference
Ultmsound: THE REQUISITES, pp 1 26- 1 33 .
Comment
Chronic calcific pancreatitis is a complication of prolonged
alcohol abuse. It is believed that alcohol predisposes
to the precipitation of proteins in the side
branches of the pancreatic duct. These proteins attract
calcium carbonate and form stones that obstruct the
peripheral side branches, resulting in an inflanunatory
response that causes parenchymal damage and, ultimately,
periductal fibrosis. Side branch strictures and
ectasia result from the scarring and from the intraductal
concretions. With more advanced disease, the main pancreatic
duct becomes involved, with alternating strictures
and dilatation.
On sonography, chronic pancreatitis is seen as some
combination of parenchymal changes and alteration in
the main pancreatic duct. The ductal dilatation is usually
irregular, sometimes producing a "chain of lakes" appearance.
The parenchyma appears heterogeneous and
may become extremely atrophic. Punctate foci of increased
echogenicity reflect underlying calcification,
which may be focal or diffuse. They may produce no
detectable shadowing or may shadow so much that the
deeper aspects of the gland cannot be visualized.
Up to one third of patients with chronic pancreatitis
have a focal inflammatory mass in the pancreas. These
masses are usually located in the pancreatic head and
may cause dilatation of the common bile duct and the
pancreatic duct. Therefore, they can be difficult to distinguish
from pancreatic carcinoma. The presence of
1 50
calcifications strongly supports the diagnosis of chronic
pancreatitis . When calcifications are absent and especially
when the mass is hypoechoic, ERCP and biopsy
should be considered to further evaluate for possible
malignancy.

Front 138

Two views of the g a l l b l adder.
1 . What technique was used to allow the gallbladder sludge to be better seen on the second image?
2 . Is this technique theoretically more important in thin patients or in obese patients?
3. Is this technique theoretically more important for high or low frequency transducers?
4. Is this technique possible on all transducers?

Back 138

Tissue Harmonic I maging
1. The second image used tissue harmonic imaging
(THI) to improve visualization of the sludge.
2. THI has a greater impact in obese patients, but it
can help in thin patients as well.
3. THI is theoretically more important for low
frequency transducers.
4. THI can be installed on all transducers.
Reference
Choudhry S, Gorman B, Charboneau ]W; et al: Comparison
of tissue harmonic imaging with conventional US
in abdominal disease. Radiographics 2000;20: 1 1 27-
1 1 3 5 .
Comment
Conventional ultrasound transmits pulses of a certain
fundamental frequency spectrum and receives echoes
at the same frequency. As the sound pulse interacts with
the tissues that it travels tlu-ough, harmonic signals that
are multiples of the fundamental frequency are generated.
This is analogous to the overtones of a musical
note. These harmonic components build up at increased
depth and then decrease owing to attenuation. Although
multiple harmonic frequencies are present, the higher
harmonics are very low in amplitude. With current
harmonic imaging technology, only the second harmortic,
which is twice the fundamental frequency, is
used. In this case, the image was created by transmitting
at 1 .6 MHz and analyzing the 3 . 2 MHz harmonic Signal
after the 1 .6 MHz echoes were filtered out.
Because the harmonic signal is a higher frequency,
axial resolution improves with harmonic imaging. Additionally,
the harmonics allow for better focusing, which
also inlproves lateral resolution. Side lobes and scattering
are both less prominent with harmonic frequencies,
and this leads to less artifacts. Finally, harmonic signals
are generated beyond the body wall, and this helps to
avoid the defocusing effects of the body wall.

Front 139

Pulsed Doppler waveforms from the femoral a rtery.
1 . Which velocity is more reliable?
2. What happens to the Doppler frequency shift when the Doppler angle approaches 0 degrees?
3. What happens to the Doppler frequency shift when the Doppler angle approaches 90 degrees?
4. How can the Doppler angle be changed?

Back 139

Relationship of Velocity Calculation
Accu racy to Doppler Angle
1. The first velocity is more accurate because the
Doppler angle is less than 60 degrees. The second
velocity should not be trusted because the Doppler
angle is greater than 60 degrees.
2 . The frequency shift is maximized as the Doppler
angle approaches 0 degrees.
3. The frequency shift is minimized as the Doppler
angle approaches 90 degrees.
4. With linear array transducers, it is possible to steer
the Doppler beam to one side or the other (as was
done in the first image) so that the Doppler angle
will change. With other transducers, the only way
to change the Doppler angle is to change the
position of the transducer so that the orientation of
the Doppler beam with respect to the vessel also
changes.
Reference
Taylor K]W; Holland S: Doppler US: Part 1. Basic principles,
instrumentation, and pitfalls. Radiology 1 990;
1 74: 297-307.
Cross-Reference
Ultrasound: THE REQUISITES, pp 467-468.
Conunent
In many situations, it is important to calculate blood
flow velocities. This can be done by rearranging the
Doppler equation to solve for velocity, as shown:
v = Fd X 11Ft X C X l/cos6 X 1 /2
In this equation, V = velocity, Fd = Doppler frequency
shift, Ft = transmitted frequency, C = the speed of
sound, and 6 = Doppler angle. If it were possible to
determine the exact Doppler angle, then an accurate
velocity could be calculated almost regardless of the
Doppler angle. Unfortunately, it is not possible to determine
the exact Doppler angle. Part of the problem is
that there is always some degree of error in the angle
estimation when the angle indicator line is rotated parallel
to the axis of the vessel. In addition, blood flow is
rarely oriented directly along the long axis of the vessel.
Some flow is oriented toward the vessel walls, and some
is oriented out of the imaging plane. Therefore, there is
always an unavoidable error in the determination of the
precise Doppler angle.
TItis inherent error has important implications in
calculating flow velocities. As can be seen from the
preceding equation, velocity is proportional to l/cos6.
If one were to draw a graph that plots l/cos6 with
respect to 6, it would show that at Doppler angles less
1 52
than 60 degrees, there is little change in 1/cos6 despite
large differences in the angle 6. However, above 60
degrees, small differences in the angle 6 produce large
differences in the value of l/cos6 . Therefore, it is unportant
to mau1tain a Doppler angle of 60 degrees or
less when attempting to calculate flow velocities. When
this is not possible, it should be recognized that significant
errors can be made.

Front 140

Wavefo rms of the vertebral a rtery taken 1 day apart.
1 . Which of the waveforms is abnormal?
2. What is the Significance of this waveform abnormality?
3. What would you consider if this waveform abnormality were seen in multiple abdominal and
peripheral arteries?
4. What would you consider if this waveform abnormality were seen in the lower pole of a kidney while
a normal waveform was seen in the upper pole?

Back 140

Parvus-Tardus Waveform
1 . The first is abnormal.
2. In the proper clinical setting, it indicates a proxin1al
arterial stenosis. In this case, a second image
demonstrates a normal waveform obtau1ed after a
vertebral artery stent was placed across a proxiInal
stenosis.
3. Aortic valvular stenosis or coarctation should be
considered.
4. Stenosis of an accessory artery to the lower pole
should be considered.
Reference
Bude RO, Rubin JM, Platt et al: Pulsus tardus: Its cause
and potential limitations in detection of arterial stenosis.
Radiology 1 994; 1 90:779-784.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 1 1 - 1 1 2 .
Conunent
Normal arterial waveforms demonstrate an extremely
rapid early systolic upstroke because there is fast acceleration
of blood at the initiation of systole. The first
waveform shown in this case demonstrates a very
slowed systolic upstroke and a systolic peak that is
reduced when compared to the amount of diastolic
flow. These changes are referred to as parVlls (reduced
amplitude) and tardus (delayed). This type of waveform
is also frequently described as being blunted.
ParVlls-tardus waveforms are most frequently the result
of a significant proximal stenosis. The maxinmlTI
effect of the stenosis occurs during systole when the
pressure is the greatest. The overall velocity in peak
systole is reduced beyond the stenosis, and the time it
takes to reach maxiInum velocity (acceleration) is also
reduced. Since pressure is lower duru1g diastole, the
effect on diastolic flow is less. Therefore, the difference
between systolic flow and diastolic flow is less than
normal, and the waveform appears blunted. In severe
cases, the difference between systole and diastole may
be so minimal that the arterial waveform appears more
like a venous waveform.

Front 141

Views of the intra hepatic and extrahepatic portion of the l iver h i l u m
i n two patients.
l . What is the abnormality in the first in1age?
2 . What is the abnormality in the second unage?
3. What is the most common location for this lesion?
4. How is the diagnosis confirmed?

Back 141

Cholangiocarcinoma
1. Dilated intrahepatic ducts abruptly terminate at the
level of a soft tissue mass.
2. A dilated common hepatic duct terminates abruptly
at the level of a suprapancreatic mass. The distal
duct is normal in diameter.
3. Cholangiocarcinomas most commonly occur at the
confluence of the left and right bile ducts. The
lesion in the first image is located here. The lesion
in the second unage is Ul the mid duct.
4. The diagnosis is confirmed either by ultralumUlal
brush biopsies or by percutaneous biopsy with
ultrasound guidance. Pathology is notoriously
difficult; therefore, a negative biopsy result should
not be considered definitive, especially Ul the
presence of convincing imaging tests.
Reference
Bloom CM, Langer B, Wilson SR: Role of US in the
detection, characterization, and stagulg of cholangiocarCUloma.
Radiogmphics 1999 ; 1 9: 1 1 99 - 1 2 1 8.
Cross-Reference
Ultrasound: THE REQUISITES, pp 63-66.
Comment
Cholangiocarculoma (CCa) is relatively rare, accounting
for less than 1% of malignant neoplasms. It generally
occurs in the sixth or seventh decade of lite. In the
majority of cases, there is no known etiology. However,
predisposulg factors include cystic disease of the bile
ducts (choledochal cysts and Caroli's disease), sclerosulg
cholangitis, ulcerative colitis, Thorotrast exposure, and
hepatic parasitic infection. The prognosis is dismal, with
a 5-year survival rate of approxinlately 1 %. Even with
curative resection, the 5-year survival rate is only 20%.
CholangiocarculOma most often affects the extrahepatic
ducts. As many as 70% of cases occur at the
bifurcation of the common hepatic duct. Tumors in
this location are often referred to as Klatskin tumors.
Typically, Klatskitl tumors are small at the tinle of presentation.
They tend to ulfiltrate the wall of the duct,
the adjacent vessels, and the adjacent liver parenchyma.
Involvement of adjacent vessels and extension into the
more peripheral aspects of the bile ducts beyond the
bifurcation determule whether the tumor is resectable
and what type of resection can be performed.
Sonographically, most Klatskitl tumors appear as a
relatively isoechoic mass in the liver hilum. In many
cases the margins of the mass are best identified by
noting the location of transition of the dilated bile ducts.
An important aspect of the sonographic examulation is
determining the extent of ulVasion of the adjacent ves-
1 54
sels. Soft tissue encasement of the vessels is a reliable
sign of ulVasion.
Ten percent to 20% of cholangiocarcinomas occur in
the intrahepatic bile ducts. In this location they usually
grow to be quite large, since they do not produce early
symptoms. Sonographically they appear as nonspecific
solid masses that vary in their echogenicity.
The remaitlder of cholangiocarcinomas occur in the
common bile duct and common hepatic duct below the
bifurcation. These tumors may be infiltrative or polypoid
in nature. 1\.ul1ors Ul the most distal aspect of llie duct
can be easily confused bOtll clitlically and patllologically
willi ampullary, duodenal, and pancreatic cancers. l1lerefore,
tllis group of ttul10rs is often referred to as periampullary.
In tllis location, smgical resection is much more likely
to be possible and to be successful.

Front 142

Lon g itudinal and tran sverse views of the gallbladder.
1 . If this patient had intermittent bouts of severe right upper quadrant pain lasting a few hours, would a
cholecystectomy be uldicated?
2. What is the major sonographic difference between stones and sludge?
3. What is the sonographic sensitivity for gallstones?
4. What is the sonographic negative predictive value for gallstones?

Back 142

Gal lstones
1 . This patient has multiple small stones. Internlittent
bouts of right upper quadrant pain represent biliary
colic as these stones pass tlu'ough the cystic duct.
This patient would almost certainly benefit from
cholecystectomy.
2 . Sludge does not shadow, and all but the smallest
gallstones do shadow.
3 . Sonograpllic sensitivity for gallstones is greater than
95%.
4. Negative predictive value for gallstones is greater
than 95%.
Reference
Middleton WD: Right upper quadrant pain. In Bluth
EI, Benson C, Arger P, et al (eds): The Pmctice of
Ultrasonography New York, Thieme, 1 999, pp 3 - 16.
Cross-Reference
Ultmsound: THE REQUISITES, pp 38-4 1 .
Comment
In this case, a thin layer of small stones rests along the
dependent wall of the gallbladder. Notice that the stones
are much easier to appreciate on the transverse view
than on the longitudinal view. On the longitudinal view,
it is easy to confuse the echogellic layer of stones for
the back wall of the gallbladder. This is less of a problem
on the transverse view. In addition, the shadow caused
by the stones is narrower on the transverse view and is
easier to pick out from the adjacent tissues. In a case
such as thiS, it is important to unage the patient in
different positions because the stones may rearrange
into a configuration that is easier to appreciate.

Front 143

Views of the l iver i n two patients.
1 . Describe the abnormality.
2 . What is the descriptive term for this finding?
3. With what is this finding classically associated?
4. How useful is this finding?

Back 143

Hepatitis
1. Both views show increased echogenicity of the
portal triads in the periphery of the liver.
2. This is referred to as the "starry sky" sign.
3. The starry sky sign is classically associated with
hepatitis.
4. Usefulness of this sign is limited because (unlike
this case) it is usually very subtle, and it can be
seen in patients who have no other clinical or
laboratory evidence of hepatitis.
Reference
Kurtz AB, Rubin CS, Cooper HS, et al: UltraSOtllld findings
in hepatitis . Radiology 1980; 136:717-723.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 112-115 .
Conunent
Patients with right upper quadrant pain and abnormal
liver fu nction tests often are referred fo r sonographic
evaluation. The main goal in this group of patients is to
determine whether there are gallstones and whether
there is any evidence of biliary obstruction. In the absence
of either of these abnormali ties, the next consideration
is usually diffuse liver parenchymal disease.
Except fo r fa tty infiltration, ultrasound is not a good
way of evaluating or quantitating diffuse liver disease.
Hepatitis is no exception. Nevertheless, there are some
sonographic findings that are seen in patients with hepatitis.
Perhaps the most C0 1111110n abnormality is thickelung
of the gallbladder wall (see case 13). In fa ct,
hepatitis can produce dramatic gallbladder wall tluckening.
It is also characteristic of patients with hepatitis
fo r the gallbladder lumen to be contracted. Another
finding seen C01111110nly is nlildly enlarged lymph nodes
in the porta hepatis, around the celiac axis, and in
the peripancreatic area. Unfortunately, nlildly enlarged
nodes are very C01111110n in these areas and can be
associated with many other inflammatory or infectious
conditions in the right upper quadrant . They are also
common in liver diseases other than hepatitis, such as
primary biliary cirrhosis and sclerosing cholangitis.
This case demonstrates the starry sky sign in the
liver. Decreased echogenicity of the liver parenchyma
around the portal veins is fe lt to be the cause, although
increase in the echogenicity of the periportal tissues
may also be at least partially responsible . Regardless of
the cause, when the portal tracts are in1aged in cross
section in the periphery of the liver, the net result is
small fo cal areas of increased echogenicity on a darker
background, simulating stars in the night sky. Although
this finding was described in association with hepatitis,
it is not terribly helpful owing to poor sensitivity and a
158
limited positive predictive value. In addition, when it
is present, it is usually subtle enough that diagnostic
confidence is limited. The changes seen in this case are
considerably more striking than are usually seen.

Front 144

Two views of the spleen.
1 . Describe the abnormality.
2 . What is your diff erential diagnosis?
3. If this patient were African American and had mediastinal and bilateral hilar adenopathy, what would
be your leading diagnosis?
4 . What other abdominal findings might you expect?

Back 144

Splenic Sarc oid
1. Patchy hypoechoic areas in the spleen.
2. The differential diagnosis includes lymphoma,
metastatic disease, sarcoidosis, infarction, and
infection.
3. Sarcoidosis would be most likely, although
lymp homa would also be a consideration.
4. Abdominal sarcoid also affects the liver and causes
lymphadenopathy.
Reference
Wa rshaur DM, Molina PL, Hamman SM, et a1: Nodular
sarcoidosis of the liver and spleen: Analysis of 32
cases. Radio logy 1995; 1 95:757-762 .
Cross-Reference
Ultr·asou nd: THE REQUISI TES, P 145.
Conunent
Sarcoidosis is a disease of unknown etiology that affects
primarily the chest but can involve virtually any organ
in the body. It is characterized by noncaseating granulomas
in lymph nodes as well as in organs with a rich
lymphatic supply. Approxin1ately 50% of patients are
asymptomatic at the time of diagnosis, so the disease
can be detected as an incidental finding during abdominal
sonography.
Sarcoidosis involves the abdominal lymph nodes in
approximately 30% of cases. Ly mph nodes are commonly
seen in the region of the porta hepatis, celiac
axis, pancreas, and retroperitonelUll . Involvement of the
liver and spleen is also seen in approximately 30% of
cases. Tlus is usually manifest as d iffuse enlargement of
the liver or spleen, but fo cal lesions can also be seen. It
is extremely difficult to distinguish abdominal sarcoidosis
from abdominal lymphoma purely on the basis of
imaging findings.

Front 145

Two-dimensional and three-dimensional power Doppler views of the
l iver i n two patients. (See color plates.)
1 . Describe the findings.
2 . What is the natural history of this lesion?
3. What is the best way of confirming the diagnosis?
4. Would the presence of central calcification change your approach to this lesion?

Back 145

Hepatic Focal Nodular Hyperplasia
1 . The first image shows a collection of vessels
arranged in a spokewheel configuration. The
underlying grey-scale appearance of the liver is
barely distorted. The second image also shows a
spokewheel configuration in three dimensions.
2. Focal nodular hyperplasia rarely causes clinical
symptoms and has no malignant potential.
3. Currently the most definitive imaging means for
confirming the diagnosis is sulfur colloid scanning.
4. Central calcification suggests the diagnosis of
fibrolamellar hepatocellular carcinoma and would
prompt a more aggressive approach
Reference
Buetow PC, Pantograg-Brown L, Buck JL, et al : From the
archives of the AFIP: Focal nodular hyperplasia of the
liver: Radiologic-pathologic correlation. Radiographies
1 996; 1 6: 369-388.
Cross-Reference
Ultrasound: THE REQUISITES, P 1 4 .
Comment
Focal nodular hyperplasia (FNH) is a benign tumor of
the liver that is composed of Kupffer cells, hepatocytes,
and biliary structures. It is hypothesized that it develops
from a congenital vascular malformation that promotes
hepatocellular hyperplasia. Pathologically, it often has a
central, stellate scar. It is supplied by an internal arterial
network that is arranged in a spokewheel pattern.
FNH is usually detected as an incidental mass on CT
or on ultrasound. Like hepatic adenoma, FNH is more
common in women. Unlike hepatic adenoma, it is not
related to the use of birth control pills. The nodules
seldom bleed or cause any clinical symptoms, although
pain may be encolmtered when the lesions are large.
Although the appearance of FNH varies on sonography,
most FNHs are isoechoic or nearly isoechoic to
liver parenchyma. The central stellate scar, which is
frequently seen on CT and MRI, is uncommonly seen
on ultrasound. However, the spokewheel pattern of internal
vascularity is better displayed on color or power
Doppler than on CT or MRI.
When FNH is suspected based on ultrasound, hepatic
scintigraphy with sulfur colloid can be very useful. Due
to the concentration of Kupffer cells, approximately
60% of FNHs are either hot (more intense than adjacent
liver) or warm (isointense to adjacent liver). The typical
features on ultrasound and these findings on sulfur colloid
scans are sufficient to make the diagnosis with a
high degree of certainty. If the lesion is cold on sulfur
colloid scans, then FNH remains a possibility, but other
lesions also need to be considered.

Front 146

Long itudinal grey-scale and color Doppler views of the thyroid. (See
color plates.)
1 . Describe the abnormality shown on the grey-scale view.
2 . Describe the abnormality shown on the color Doppler view.
3. Is tItis condition more common in men or in women?
4. Would you be surprised if tills patient were hypothyroid?

Back 146

Hashimoto's Thyroiditis
1. The thyroid is mildly enlarged, hypoechoic, and
diffusely heterogeneous, without discrete focal
nodules.
2. The thyroid is very hypervascular.
3 . Hashimoto's thyroiditis is much more common in
women.
4. Hashimoto's thyroiditis is the most common cause
of hypothyroidism in the United States.
Reference
Yeh HC, Futtelweit W, Gilbert P: Micronodulation: Ultrasonographic
sign of Hashimoto'S thyroiditis. ] Ultrasound
Med 1 996; 1 5 : 8 1 3-8 1 9.
Cross-Reference
Ultrasound: THE REQUISITES, P 452.
Comment
Hashimoto's thyroiditis (also called chronic autoimmlme
lymphocytic thyroiditis) is believed to be due to autoantibodies
to thyroid proteins, especially thyroglobulin.
Therefore, the diagnosis is often made serologically. The
gland is infiltrated with lymphocytes and plasma cells,
with an associated fibrotic reaction. Patients may be
euthyroid initially but generally become hypothyroid
owing to replacement of fimctioning thyroid parenchyma.
It has a peak incidence between the ages of 40
and 60 years and is six tinles more common in women
than in men. Other autoimmume disorders such as Sjogren's
syndrome, systemic lupus erythematosus, rheumatoid
artlu·itis, fibrosing mediastinitis, sclerosing cholangitiS,
and pernicious anemia may coexist with
Hashimoto'S thyroiditis. There appears to be a slight
increased risk of thyroid lymphoma in patients with
Hashimoto'S thyroiditis.
On sonography, the gland is hypoechoic and usually
enlarged. Generally the normal homogeneous echotexture
is replaced by a more heterogeneous texture. Thin,
echogenic fibrous strands may cause a multilobulated or
micronodular appearance. Often the gland is extremely
hypervascular. Hashimoto'S thyroiditis can cause nodules,
and other types of benign and malignant nodules
can coexist with Hashimoto's thyroiditis. In the end
stage, the gland becomes atrophic.

Front 147

Longitudinal view of the rig ht upper quadrant and transverse view of
the aorta and left u p per quadrant i n two patients.
1 . What do these two patients have in common?
2. What is included in the differential diagnosis?
3. If there were a history of hypertension, what would be the most likely diagnosis?
4. If there were a history of medullary cancer of the thyroid, what would be the most likely diagnosis?

Back 147

Ad renal Masses
1 . The first image shows a mass posterior to the liver.
A portion of the normal adrenal gland is seen
extending inferior to this mass. The second image
shows a mass lateral to the aorta.
2. The differential diagnosis for adrenal masses
includes adenomas, pheochromocytomas (second
un age) , myelolipomas, adrenal cancer, metastases
(fu'st image), lymphoma, and hematomas.
3. Hypertension can be caused by
pheochromocytomas and by functioning adenomas
that secrete aldosterone (Conn's disease).
4. Medullary thyroid cancer and an adrenal mass
should suggest multiple endocrine neoplasia (MEN),
type II. The adrenal mass would then be a
pheochromocytoma.
Reference
Krebs TL, Wagner BJ: MR imaging of the adrenal gland:
Radiologic-pathologic correlation. Radiographies
1 998; 1 8 : 1425- 1 440.
Cross-Reference
Genitourinary Radiology: THE REQUISITES, pp 346-
3 5 5 .
Comment
Ultrasonography generally does not unage normal adre·
nal glands. Nevertheless, ultrasound frequently identifies
masses in the right adrenal gland and ulfrequently identi·
fies left adrenal gland masses. Right adrenal masses can
be imaged from an intercostal or a subcostal approach.
Masses appear immediately adjacent to the posterior
surface of the liver and lateral to the inferior vena cava.
Right adrenal masses are usually superior to the upper
pole of the kidney. Left adrenal masses are located in a
left para-aortic location at the level of the upper pole of
the kidney. They are best identified from a left coronal
intercostal approach, using the spleen or kidney as a
window, or from an anterior subxiphoid approach.
The most common adrenal mass is the adenoma.
Autopsy series identify adenomas in 3% of the population.
Adenomas are usually asymptomatic but can produce
CuShi..tlg'S syndrome (excessive glucocortisol) and
Conn's syndrome (hyperaldosteronism). They contaul
significant amounts of lipid and are typically low attenuation
lesions on CT. They are usually less than 3 cm ill
size and homogeneous. Despite their small size, the
adrenals are the fourth most conunon site of metastases.
Metastases are usually larger than adenomas and are
heterogeneous. Pheochromocytomas produce symptoms
of hypertension, headache, tachycardia, anxiety,
and palpitations. They are referred to as "the 10% tumor"
because 1 0% are malignant, 1 0% are extra-adrenal,
1 0% are bilateral, and 1 0% occur with MEN syndromes.
1 62
Pheochromocytomas are typically large, vascular, heterogeneous
tumors. Primary adrenal carcinomas are
very rare tumors. They are typically very large masses
that present with pain or symptoms due to the mass
effect. NecrOSis, hemorrhage, and calcification are common.
Myelolipomas are benign tumors that contaul hematopoietic
and fatty elements. They rarely cause symptoms
and can be small or large.
There is significant overlap in the sonographic appearance
of various solid adrenal masses. In most cases,
sonographic detection of an adrenal mass is followed
by CT or MRI for further characterization. In some
instances, laboratory studies are sufficient to determme
the etiology of an adrenal mass. In this case, the lesion
shown in the fu'st unage was a right adrenal metastasis
in a patient with lung cancer. The lesion shown in the
second image was a left adrenal pheochromocytoma Ul
a patient referred for a renal artery Doppler scan. Urinary
catecholamule levels documented the diagnosis.

Front 148

Tra nsverse and longitudinal views of the penis.
1 . Describe the abnormality.
2 . What is the physical examination of the penis likely to reveal?
3. What symptoms is this patient likely to have?
4 . Is this more common along the dorsal or ventral surface of the penis?

Back 148

Peyronie's Disease
1 . Calcification of the tunica albugulea of the corpora
cavernosa.
2. Localized firmness and thickening at lie site of the
plaque.
3. Paulful and/or curved erections.
4. This is most common on the dorsal side of the
peniS.
Reference
Balconi G, Angeli E, Nessi R, et al: Ultrasonographic
evaluation of Peyronie's disease. Urol Radiol 1 988;
1 0:85-88
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 1 2 - 1 1 5 .
Comment
Peyronie's disease is fibrosis of the tunica albuginea of
the corpora cavernosa. It is idiopathic and typically
affects men older than 45 years. Since the tunica albuginea
calUlot stretch in the area of fibrosis, the peniS
bends toward the plaque durulg erection. Pain and penile
curvature can make intercourse impossible.
On sonography, the plaques appear as localized areas
of thickening of the tunica albuginea. They are often
hyperechoic and may be calcified. The typical location
is along the dorsum of the penis near the base, but
Peyronie's disease can also involve the lateral margins
and the septum.

Front 149

Transverse views of the shoulder i n two patients.
1 . What do these patients have in common?
2. Which patient requires further imaging for confirmation of the diagnosis?
3 . How does ultrasound compare to MRI in making this diagnosis?
4. In which patient is the diagnosis most likely to be apparent on radiographs of the shoulder?

Back 149

Full Thickness Rotator Cuff Tea r
1 . Both patients have full thickness rotator cuff tears.
The first image shows a contour concavity, and the
second shows nonvisualization of the cuff.
2 . The findings on sonography are diagnostic in both
cases. No further imaging is required .
3 . In the hands o f experienced sonologists and
experienced MRI readers, ultrasound and MRI are
equivalent for detection of full thickness rotator
cuff tears.
4. The patient with nonvisualization (second image) is
likely to have superior migration of the humeral
head detectable on shoulder radiographs.
Reference
Teefey SA, Hasan SA, Middleton WD, et al: Ultrasonography
of the rotator cuff: A comparison of ultrasonography
and arthroscopic surgery in one hundred consecutive
cases. J Bone JOint Surg 2000;82(A):498-504.
Cross-Reference
Ultrasound: THE REQUISITES, pp 455-457.
Comment
Full thickness rotator cuff tears are classified as wet or
dry, depending on whether there is a significant amount
of joint fluid surrounding the torn edges of the cuff. In
the patients shown in tl1is question, the tears are dry.
The appearance of dry tears is somewhat more difficult
to understand than wet tears. When the defect created
by the tear is not filled with fluid, it must be filled with
something else. In most cases, the overlying subdeltoid
bursa and peribursal fat drops into the defect. This
produces a concavity in the reflections from the bursa
and fat. In most cases, tl1is concavity is readily visible at
rest. If the torn ends of the tendon have not retracted
from each other, a concavity may not be visible at rest.
In such a case, compression of the shoulder with the
transducer can push the bursa and peribursal fat into
the defect at the same time that it produces some
separation of the tendon ends. Compression can also
exaggerate some tears that are otherwise subtle because
they are filled with hypertrophied synovial tissue. This
is presumably due to the greater compressibility of the
thickened synovium compared to the rotator cuff. In
the absence of a tear, the normal rotator cuff does not
compress at all.
When there is a massive tear with extensive retraction
of the torn tendon, the humeral head becomes
completely uncovered by cuff tissue. In such a situation,
there is no sonographically visible cuff on standard images.
This is referred to as nonvisualization of the cuff.
In these cases, the subdeltoid bursa, peribursal fat, and
deltoid muscle come into direct contact with the articular
cartilage and humeral head.

Front 150

Transverse g rey-scale view and longitudinal color Doppler view
of the rig ht kidney. (See color plates.)
1 . Describe the abnormality.
2 . What is the most likely diagnosis?
3 . Is this the most common location for this lesion?
4. How is this lesion treated?

Back 150

Transitional Cell Carcinoma
1. The first image shows a solid mass in the renal
lillum. The second image shows the mass with
minimal internal vascularity and multiple lillar
vessels draped around its margins.
2. Both of the finclings should suggest transitional cell
carcinoma.
3. No. Most transitional cell cancers occur in the
bladder.
4. Upper tract transitional cell cancer is treated with
nephrectomy and ureterectomy.
Reference
Wong-You-Cheong JJ, Wagner BJ, Davis CJ, Jr: From the
archives of the AFIP: Transitional cell carcinoma of
the urinary tract: Radiologic-pathologic correlation.
Radiographies 1 998; 1 8: 1 23 - 1 42 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 94-95.
Comment
Transitional cell cancer (TeC) is typically divided into
tumors that involve the bladder and tumors that involve
the upper urinary tract (ureter, renal pel.vis, and intrarenal
collecting system). Bladder tumors are much more
common than upper tract tumors, and tumors of the
renal pelvis are more common than tumors of the ureter.
Approximately 90% of renal pelvis tumors and 99%
of ureteral tumors are TCe.
Patients most often present with gross hematuria.
Flank pain is uncommon and usually indicates obstruction
and hydronephrosis. Colicky pain may develop during
periods of clot passage. Patients with advanced disease
may present with constitutional symptoms such as
weight loss and anorexia.
Sonography is not a primary means of evaluating
patients with Tee of the upper urinary tract. However,
it may be the first test obtained in a patient with hematuria,
and thus the u1itial identification of the tumor may
be with ultrasound. Tee has a variety of sonograpl1ic
appearances. It may appear as a solid mass witl1in a
dilated renal pelvis, as a solid mass distorting the renal
sin us fat, or as an area of uroepithelial tl1ickel1ing. In
general, the sonographic findu1gs are non-specific, and
the differential diagnOSiS includes blood clots, sloughed
papillae, and pyelonephritis. Detection of internal vascularity
confirms that the lesion is viable soft tissue and
almost always indicates a tumor of some sort. Further
evaluation with u1travenous urography, retrograde pyelography,
or ureteroscopy is generally required.

Front 151

Transverse views of the l iver.
1 . Describe the abnormalities in these images.
2 . If there is a history of trauma, what is the most likely diagnosis?
3. How effective is ultrasound in establishing this diagnosis?
4. What role , if any, does ultrasound have in evaluating trauma patients?

Back 151

Liver Laceration and Hemoperitoneum
1 . The first image shows peritoneal fluid around the
liver. The second unage shows mild distortion of
the liver echo texture.
2. In the settulg of trauma, any peritoneal fluid should
be assumed to be a hemoperitoneum. The subtle
changes in the liver indicate that the liver is the
likely source as a result of a hepatic laceration.
3. Ultrasound is good at identifyulg hemoperitoneum.
It is not very good at identifying an acute laceration
of a parenchymal organ such as the liver, spleen, or
kidney.
4. The role of ultrasound in the setting of blunt
abdominal trauma is controversial and Ul evolution.
It is clear that ultrasound can substitute for the
diagnostic peritoneal lavage. Given this, some
believe that ultrasound should be used to identify
patients with hemoperitoneum.
Reference
Richards JR, McGahan JP: Ultrasound for blunt abdominal
trauma Ul the emergency department. Ultrasound
Q 1 999; 1 5(2):60-72.
Cross-Reference
Gastrointestinal Radiology: THE REQUISITES, pp 1 74-
175.
Comment
The use of ultrasound in the evaluation of blunt abdominal
trauma is u1creasing world-wide. Ultrasound is a
rapid and effective means of detecting hemoperitoneum
and has become one of the initial checkpoillts in the
triage of blunt abdorni11al trauma patients. If the patient
has fluid detectable on ultrasound, has a positive physical
examination, and is hemodynamically unstable, then
an emergency abdominal exploration is performed to
identify and correct the site of bleedu1g. If the patient
is stable, further evaluation may be obtained with either
CT, follow-up ultrasOtU1d, or laparotomy. If the patient
has no fluid, or has fluid but is stable and has a negative
physical examu1ation, then he or she is observed cluucally.
If the clinical status deteriorates, then CT, followup
ultrasound, or laparotomy is performed. If the patient
remains stable and unproves, no further evaluation
is carried out.
Problems in the use of ultrasound include its limited
ability to identify and grade liver, splenic, renal, pancreatic,
mesenteric, and bowel lacerations. As shown in
tlus case, acute hemorrhage in solid organs may be very
subtle on sonography. In addition, hemoperitoneum
may be absent with isolated retroperitoneal injuries and
may initially be minimal or absent with injuries to the
1 66
bowel, mesentery, or contamed uljuries to the liver and
spleen. On the other hand, sunple ascites may be present
and sunulate hemoperitoneum. Finally, quality-degrading
factors such as obesity, excessive bowel gas,
subcutaneous emphysema, and pneumoperitoneum
may limit the exarni11ation.

Front 152

Longitudinal view of the right u pper q u adrant and transverse view of
the mid abdomen.
1. Describe the abnormality.
2 . What is the differential diagnosis?
3. What is the best way to confirm the diagnosis?

Back 152

Perito neal Metastases
1 . The first unage shows two solid, hypoechoic masses
between the surface of the liver and the abdominal
wall. The second unage shows a sin1ilar mass in the
nud abdomen, also adjacent to the anterior
abdorni11al wall. This appearance is typical of
peritoneal metastases. Tlus patient had a prunary
bronchogenic cancer.
2. Other possibilities include splenosis, endometriosis,
mesothelioma, and tuberculosis.
3. If confirmation of the diagnosis were necessary,
ultrasound guided biopsy would be the most
straightforward approach.
Reference
Yeh HC: Ultrasonography of peritoneal tumors. Radiology
1 979; 1 33 :4 1 9-424.
Comment
Peritoneal metastases most often arise from gynecologic
tumors or tumors of the gastrou1testinal tract (especially
colon, stomach, and pancreas). Breast cancer, lung cancer,
and melanoma are also capable of metastasizing to
the peritoneum. Peritoneal metastases are often small
and not visualized by any imaging tecluuque. When
they reach 1 cm or greater ill size, they can be detected
sonographically. As shown ill this case, peritoneal tumor
implants typically appear as discrete masses that are
separate from bowel. The best way to identify them is
to use a transducer with high near-field resolution, such
as a linear or curved array transducer. Tumor unplants
are most often seen immediately deep to the abdominal
wall, so it is important to focus attention to this superficial
area. As the transducer is swept up and down the
abdomen, peritoneal nodules will appear and disappear
from view. Tlus distinguishes them from bowel loops,
wluch are contU1ll0US and connected to other bowel
loops.

Front 153

Lon g itu dinal and tra n sverse color Doppler views of the testis. (See color pl ates.)
1 . Identify the vessels that are labeled on the images in this case.
2. How is testicular blood flow different from blood flow in other organs?
3 . Is the testis as vascular as the epididymis?
4. What arteries are located in the spermatic cord?

Back 153

Normal Testicular Vasculature
1 . 1 Capsular artery, 2 = Centripetal artery,
3 = Recurrent ramus, 4 = Transmediastinal artery,
5 = Transmediastinal vein.
2. The largest testicular arteries are located on the
surface of the organ.
3. The testis demonstrates more vascularity than the
epididymis on color Doppler.
4. In addition to the testicular artery, the cremasteric
artery and the deferential artery are located in the
spermatic corel.
Reference
Middleton WD, Bell MW: Analysis of intratesticular arterial
anatomy with emphasis on transmediastinal arteries.
Radiology 1 993 ; 1 89: 1 57- 1 60.
Cross-Reference
Ultrasound: THE REQUISITES, P 43 5 .
Comment
Arterial supply of the scrotum is via the testicular artery
(which is the primary supply to the testis), the deferential
artery (which is the primary supply to the vas
deferens and epididymis), and the cremasteric artery
(which supplies the scrotal wall). The testicular artery
typically divides into two to four branches that travel
along the periphery of the testis. These are called capsular
arteries and are the largest arteries of the testis.
Capsular arteries supply branches called centripetal arteries
that head into the testis and travel toward the
mediastinum. Centripetal arteries branch into vessels
called recurrent rami that curve back away from the
mediastinum. In approximately 50% of testes, one or
more of the capsular arteries actually travels through
the mediastinum and crosses inside the testicular parenchyma
before it reaches the surface of the testis on the
opposite side. These arteries are called transmediastinal
arteries, and a typical example is seen on the transverse
image shown in this case. Doppler waveform analysis
from the various testicular arteries shows a low resistance
pattern typical of a solid parenchymal organ.
Detectable testicular veins are less numerous than
testicular arteries. However, they can be seen on many
normal testicular Doppler examinations. Some testicular
veins drain out of the mediastinum and some drain
peripherally into capsular veins. It is not uncommon to
see a large transmediastinal vein running parallel to a
transmediastinal artery, as shown in this case.

Front 154

Longitud i n a l g rey-sca le view of the i nterna l carotid a rtery a n d
longitudinal color Doppler view of t h e carotid bifurcation. (See color plates.)
1 . Describe the abnormal findings.
2. Does treatment differ for an internal carotid artery (leA) with a total occlusion compared to an artery
with a high-grade subtotal occlusion?
3 . What happens to the common carotid artery waveform when the leA is totally occluded?
4. What might cause a patent leA to appear totally occluded?

Back 154

Complete Occlusion of the I nternal Carotid
Artery
1 . The grey-scale view shows partially calcified plaque
in the internal carotid origin and low level echoes
in the proximal ICA. The color Doppler view shows
flow in the jugular vein (blue) and in the common
and external carotid arteries (red), but no
detectable flow in the ICA.
2. Patients with total occlusions are not candidates for
endarterectomies, but patients with subtotal
occlusions are candidates for this procedure.
3. The common carotid artery waveform starts to look
like that of the external carotid artery.
4. A subtotal occlusion with slow flow can be
mistaken for a complete occlusion. Other causes
include extensive calcification with shadowing and
a very deeply situated ICA.
Reference
Gortter M, Niethammer R, Widder B: Diff erentiating
subtotal carotid artery stenoses from occlusion by
colour-coded duplex sonography. ] Neural 1 994;
24 1 :30 1 -305.
Cross-Reference
Ultrasound: THE REQUISITES, P 473.
Comment
Patients with a high-grade stenosis must be distillguished
from patients with a totally occluded ICA because
the former are candidates for endarterectomy and
the latter are not. This is a potential problem for Doppler
analysis because the flow distal to a very high-grade
stenosis may be very slow and difficult to detect. Fortunately,
Doppler sensitivity ilnproved dramatically
throughout the 1 990s, and it is now very uncommon to
mistake a high-grade stenosis for a complete occlusion.
Nevertheless, tlus mistake does occur, and for tlus reason
it is common practice to perform a carotid angiogram
to confirm any questionable Doppler diagnosis of
complete occlusion.
Techniques that can be used to improve the detection
of flow ill a lugh-grade stenosis are silnilar to those
used elsewhere ill the body. One common problem in
the carotids arises when the internal carotid is deep and
high ill the neck. In such cases, it usually helps to
switch to a lower frequency probe and perhaps to a
curved array rather than a linear array. Another techluque
that can help is to elilnil1ate lateral beam steering
so that the beam is dil-ected straight down. Power Doppler
can theoretically illlprove detection of slow flow.
Intravenous microbubble contrast agents are being developed
and refined and will undoubtedly ilnprove the
situation in the future.

Front 155

long itudinal view of the lower pole of the left kid ney and tra nsverse
view of the pancreas in the same patient.
1 . What abnormalities are shown in this case?
2. What is the most likely diagnosis?
3. What other abnormalities are associated with this disorder?
4 . Are family members at risk?

Back 155

Von Hi ppel-Lindau Disease
1 . The first image shows a complex renal cyst with
thick irregular septations. The second image shows
a cyst in the body of the pancreas.
2 . This combination of findings should suggest the
diagnosis of von Hippel-Lindau disease with a cystic
renal cell cancer.
3 . Associated abnormalities include
pheoclu'omocytomas, retinal angiomas, cerebellar
hemangioblastomas, and pancreatic islet cell
tumors.
4. Von Rippel-Lindau disease is inherited as an
autosomal dominant trait, so family members are at
risk.
Reference
Choyke PL, Glenn GM, Walther MM, et al: Von HippelLindau
disease: Genetic, clinical, and imaging features.
Radiology 1 995 ; 1 94:626-642
Cross-Reference
Ultrasound: THE REQUISITES, pp 88-89.
Comment
Von Rippel-Lindau (VHL) disease is an inherited disorder
caused by a defect on the short arm of the third chromosome
that confers on patients a susceptibility to various
neoplasms and visceral cysts. More than 25 different
lesions have been reported associated with this concHtion.
However, the significant lesions that are most common
are renal cell carcinoma (25% to 50% of patients),
retinal angioma (60% of patients), central nervous system
hemangioblastoma (more than 50% of patients),
and pheochromocytoma (20% of patients). Renal cysts
are also extremely common, and pancreatic cysts are
common in certain kindreds . The diagnosis is made by
fillding a hemangioblastoma and at least one other lesion
of the VHL complex, or at least one lesion in a
patient with a family member who has a hemangioblastoma.
Patients most often present with symptoms due to
hemangioblastomas of the cerebellum or spinal cord, or
with symptoms due to visual defects related to retinal
angiomas. Hemangioblastomas account for approximately
50% of deaths, and renal cell carcinoma for
approximately 35% of deaths in these patients.
Renal cell cancers are diagnosed at a younger age in
patients with VHL. In 75% of patients, renal cell carcinoma
is bilateral, and in 90% of patients it is multiple.
In patients with VHL, renal cell cancer may be entirely
solid, or it may develop in the walls of othelwise simple
cysts. Identification of renal cell carcinoma is complicated
by the typical presence of multiple cysts. In most
patients with VHL, CT is superior to ultrasound in the
1 70
detection of renal cell carcinoma. Rowever, because of
the difference in cost, ultrasound is frequently used
instead of, or in addition to, CT in the screening of
patients with VHL. In addition, ultrasound is very useful
in characterizing complex lesions that are indeterminate
on CT. Intraoperative ultrasOlmd is also quite helpful
because it can identify cancers that are not detected
with preoperative CT or ultrasound.

Front 156

longitudinal view of the com m o n h epatic d u ct and magn ified tran sverse
view of the bile duct bifurcation in two patients.
1 . What abnormal finding is shown in this case?
2. What is the differential diagnosis?
3. Which of the possibilities would be most likely if the patient had a history of ulcerative colitis?
4. Which of the possibilities would be most likely if the lumen of the duct was completely obliterated?

Back 156

Bile Duct Wal l Thickening
1 . Both llnages show a hyperechoic inller layer and a
hypoechoic outer layer of the bile ducts. This
llldicates wall thickening.
2. The causes of bile duct thickening lllclude
sclerosing cholangitis, bile duct stones, irritation
from indwelling stents, AIDS cholangitis, oriental
cholangiohepatitis, pyogenic cholangitis,
cholangiocarcinoma, and pancreatitis.
3. Scleroslllg cholangitis is associated with ulcerative
colitis.
4. Associated luminal obliteration suggests
cholangiocarcinoma.
Reference
Middleton WD: The bile ducts. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1 993, pp 1 46- 1 72 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 66-68.
Comment
The wall of the common bile duct is normally so thin
that it is seen only as a reflection from the lllterface
between the wall and the bile m the lumen of the duct.
Whenever it is possible to resolve the thickness of the
bile duct wall, the wall should be considered to be
abnormally thick. In most cases, the thickened wall
itself will appear hypoechoic, III contrast to the bright
reflections from the internal surfaces of the anterior and
posterior walls. Although ultrasound can detect bile
duct wall thickenmg, careful correlation with clinical
information is necessary to narrow the differential diagnosis.
In many patients, further imaging with CT, magnetic
resonance cholangiopancreatography, or endoscopic
retrograde cholangiopancreatography is helpful
in establishlllg the diagnosis and determit1ing the extent
of the disease process. In both of these patients the
diagnosis was scleroslllg cholangitis.

Front 157

Two views of the pancreas i n d ifferent patients.
1 . What is the most likely reason for doing these scans?
2 . How good is ultrasound in this situation?
3. What are the two most common subtypes of this lesion?
4. Are these lesions benign or malignant?

Back 157

I ntraoperative Scans of Pancreatic
I slet Cel l Tu mors
1 . These scans are performed to localize an islet cell
tumor for surgical resection.
2. Very good. The combination of intraoperative
ultrasound and palpation detects close to 1 00% of
intrapancreatic islet cell tumors. Approximately 30%
of gastrinomas are peripancreatic, and these are
more difficult to detect with intraoperative
ultrasound.
3. The most common islet cell tumors are insulinomas
and gastrinomas.
4. Insulinomas are usually benign, and gastrinomas are
usually malignant.
Reference
Beutow PC, Miller DL, Parrino TV, Buck ]L: Islet cell
tumors of the pancreas: Clinical radiologic and pathologic
correlation in diagnosis and localization. Radiograpbics
1 997; 1 7:453-47 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 36- 1 38 .
Comment
Preoperative localization of islet cell tumors is generally
more reliable with CT than with ultrasound because
often the entire pancreas is not well visualized on sonography.
Spiral CT with early arterial phase imaging and
MRI are almost certain to further improve the noninvasive
preoperative detection of islet cell tumors. Angiography
and venous sampling are invasive techniques that
have also been reported to have sensitivity in the same
range as CT. Although ultrasound is not used routinely,
it is capable of detecting most islet cell tumors that
are 2 cm or larger and many tumors that are smaller.
Ultrasound is also a very valuable problem solving techtuque
for the portions of the pancreas that are usually
well visualized sonographicaUy, especially the body of
the pancreas and most of the pancreatic head. In fact,
for the areas that can be easily seen, ultrasound is
probably as good as, or superior to, CT and MRI in
visualizing islet cell tumors.
Unfortunately, all of the preoperative techniques are
limited, and it is not uncommon for a surgeon to operate
without being sure where the tumor is. Intraoperative
ultrasound is clearly the best way of localizing islet cell
tumors. When ultrasound is combined with intraoperative
palpation, virtually all intrapancreatic lesions can
be detected. Islet cell tumors in the wall of the duodenum
or in adjacent lymph nodes, a frequent occurrence
with gastrinomas, are more difficult to detect with intraoperative
ultrasound.

Front 158

Two views of the g a l l b l adder.
1 . What is the cause of the echoes (arrows) shown in the lumen of the gallbladder?
2 . Explain how these echoes are generated.
3. How can these echoes be eliminated?
4. Are echoes such as these seen more often in solid or in cystic structures?
1

Back 158

Side Lobe Artifact
1 . The echoes are due to side lobe artifact.
2 . When the center of the sound beam is traveling
through the lumen of the gallbladder, weak side
lobes from the center sound beam are reflecting off
strong reflectors from the surface of the gallstone.
The weak returning echo is interpreted as coming
from the center beam and is therefore placed in the
lumen of the gallbladder next to the gallstone.
3. Side lobe artifacts can be very difficult to elinunate.
Reducing power and gain may help but often do
not completely eliminate the artifact.
4. Side lobe artifacts, like most other artifacts, are seen
more often in the black background of cystic
structures than in the grey background of solid
structures.
Reference
Middleton WD: Ultrasound artifacts. In Siegel M] (ed):
Pediatric Sonograpby, 2nd ed. New York, Raven
Press, 1 994.
Comment
Most of the energy in the sound pulses that are generated
by the transducer is concentrated in the center of
the pulse. However, there are weak side lobes that
radiate out at an angle from the center beam and surround
the center beam throughout its 360-degree circumference.
Side lobes are always present to some degree,
but in most situations, the reflections generated
by side lobes are so weak that they do not produce any
identifiable echoes on the image. If the weak side lobe
reflects off a very strong reflector, the resulting echo
may be of sufficient intensity to cause an effect on the
image. Side lobes are generally only a problem when
they occur near fluid-filled structures, simply because
they are more easily appreciated in the anechoic background
of fluid-filled structures than in the echogenic
background of solid structures. In the unages shown in
this case, a gallstone produces enough of an echo that
the side lobe reflection can be seen Ul the anechoic
lumen of the gallbladder. Gas Ul the lumen of the bowel
frequently causes side lobe artifacts in the gallbladder
and the urinary bladder.
It is important to realize that the bright reflector that
causes the side lobe artifact may be located inlmediately
adjacent to, but not witllin, the imagulg plane. This can
occur because the side lobes extend completely around
the center beam (both in the plane of imaging and out
of the plane of imagulg). This explains why the artifact
is present on the first image even though the gallstone
is not seen.

Front 159

G rey-scale and color Doppler views of the l iver. (See color pl ates.)
1 . What sonographic sign is demonstrated on these scans?
2. What disease causes this sign?
3. To what is tl1is patient predisposed?
4. What other organ is usually affected with this disease?

Back 159

Caroli's Disease
1 . The images show cystic lesions with central solid
components containing blood flow. This is called
the "central dot" sign.
2. TIlls sign is characteristic of Caroli's disease.
3. Caroli's disease is associated with biliary stones, bile
duct obstruction, cholangitis, liver abscess, and
cholangiocarcinoma.
4. The kidneys are also affected with a variety of
cystic diseases.
Reference
Miller WJ, Sechtin AG, Campbell WL, Pieters PC: Imaging
findings in Caroli's disease. AIR A m I Roentgenol
I 995; 165: 333-337.
Cross-Reference
Ultrasound: THE REQUISITES, pp 69-70 .
Comment
Caroli's disease is a congenital disorder that typically
manifests first in children and adolescents. Some believe
that it is a continuum with hepatic fibrosis and autosomal
recessive (infantile) polycystic kidney disease. In
the classification scheme of choledochal cysts, it is classified
as type V In its pure form, Caroli's disease consists
of multiple areas of focal, saccular dilatation of the
intrahepatic bile ducts. The stasis of bile in the saccular
areas predisposes the patient to stone formation, intrahepatic
duct obstruction, cholangitis, and liver abscesses.
In the more common form of Caroli's disease,
there is associated hepatic fibrosis that leads to portal
hypertension and ultimately to liver failure. Cystic disease
of the kidneys is often associated with CaroB's
disease, and the clinical presentation is sometin1es dominated
by renal failure rather than by hepatic problems.
As with the other categories of choledochal cysts, patients
with Caroli's disease are predisposed to cholangiocarcinoma.
The key to the diagnosis on ultrasound is to recognize
that the cystic appearing areas of saccular dilatation
communicate with either normal or ectatic bile ducts.
A unique feature of the focally dilated ducts is that
instead of displacing the hepatic artery and portal vein,
they sometimes surround these structures. In such
cases, the vessels produce the appearance of a central
dot in the lumen of the dilated duct. When seen, the
central dot sign is highly suggestive of Caroli's disease.
The sonographic appearance of Caroli's disease is usually
typical, and the diagnosis can be made without
additional tests. However, in some instances the focal
saccular nature of the dilated ducts may be difficult to
appreciate on ultrasound, and an erroneous diagnosis
of biliary obstruction may be considered. In other cases,
1 74
it may not be apparent that the cystic spaces commlllllcate
with the bile ducts, and an erroneous diagnosis of
liver cysts may be made. In such cases, hepatobiliary
scintigraphy and cholangiography can be useful in establishing
the correct diagnosis.

Front 160

long itu d i na l g rey-scale and color Doppler images
of the l eft upper quadra nt. (See color plates.)
1 . What is unusual about these images?
2 . With what is tl1is often confused?
3. How can tills best be confirmed?
4. Should tills finding prompt further investigation?

Back 160

Normal Va riant: Left Hepatic Lobe
Over S pleen
1. A crescent-shaped hypoechoic structure is present
superior to the spleen.
2. This finding is often confused with complex
perisplenic or subcapsular fluid.
3. The etiology can best be confirmed by using
Doppler to document the vessels in tills structure.
4. This is a normal variant and requires no further
evaluation .
Reference
Li DK, Cooperberg PL, Graham MF, Callen P: Pseudo
perisplenic "fluid collection": A clue to normal liver
and spleen echogenic texture. I Ultrasound Med
1 986; 5 : 397-400.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 47 - 1 48 .
Comment
In some individuals, the left lobe of the liver extends
into the left upper quadrant. When tills happens, it
insinuates itself between the spleen and the diaphragm.
Longitudinal views of the left upper quadrant then show
the liver immediately above the spleen. Because the
normal liver is Significantly less echogelllc than the normal
spleen, the liver can be mistaken for a subcapsular
or perisplenic hematoma. It is usually not possible to
trace the left lobe in continuity with the remainder of
the liver because of interference from the left ribs and
costal cartilages and from left upper quadrant bowel
gas. However, knowledge of this normal variant usually
allows for a confident diagnosis. Correct interpretation
can be aided by identifying vessels in the left lobe of
the liver and by watclling the two organs slide with
respect to each other during respiration.

Front 161

Views of the stomach i n two patients.
1. What is the normal gut signature on sonography?
2. What abnormality is present in both linages?
3 . What is the differential diagnosis?
4. What would be an appropriate next test?

Back 161

Gastric Wall Thickening
1. Intestinal structures appear echo genic centrally and
hypoechoic peripherally.
2. Both images show thickening of the gastric wall.
3. The differential diagnosis includes peptic ulcer
disease, inflammation, or neoplastic infiltration .
4. Because ultrasound cannot determine the cause of
gastric thickening, an upper gastrointestinal tract
examination or endoscopy should be performed.
Reference
Wilson SR: Gastrointestinal tract sonography. Abdom
Imaging 1 996; 2 1 : 1 -8.
Cross-Reference
Pediatric Radiology: THE REQUISITES, pp 79-80.
COl1l1llent
Because of the presence of gas in the intestinal lumen,
ultrasound is generally not used as a primary way of
evaluating the boweL Nevertheless, ultrasound is often
capable of detecting bowel-centered pathology. With
gentle pressure, normal bowel loops can be compressed,
and air can be pressed out of the lumen. When
the bowel is well visualized on sonography, five layers
are visible. The central layer is the hyperechoic reflection
between the luminal contents and the mucosa. The
next layer is hypoechoic, and it represents the mucosa
itself and the muscularis mucosa. The tl1ird layer is
hyperechoic and represents the submucosa. The fourth
layer is hypoechoic and represents the muscularis propria.
The last and most peripheral layer is hyperechoic
and represents the serosa or adventitia. In many patients
transabdominal scanning shows only two layers.
Normal bowel wall has a thickness of 3 to 5 mm.
Localized thickening of the bowel can produce a "pseudokidney"
sign, where the luminal gas or the coapted
mucosa causes a central hyperechoic region, and the
thickened wall produces a surrounding hypoechoic
layer. The etiology of bowel wall thickening is often not
evident on sonography, and the patient'S clinical history
must be considered along with the sonographic findings.
In general, the differential diagnosis includes infectious
and inflammatory conditions, neoplastic infiltration,
edema, and ischemia.
Although ultrasound is not sensitive to gastric ulcers,
many patients with pain from ulcer disease will undergo
sonography eady in their workup for evaluation of the
other abdominal organs. Therefore, ultrasound may be
the initial study that detects the ulcer. In addition to
gastric wall thickening, ulcer craters that contain gas
may appear as bright intramural echoes with associated
dirty shadowing or ring-down artifacts. In almost all
cases, an upper gastrointestinal barium examination or
endoscopy must be performed to confirm and further
evaluate suspected gastric ulcers detected on sonography.

Front 162

Long itu d i n a l g rey-sca le and color Doppler views of the th u m b i n a
patient with a palpable mass along the volar surface. (See color p lates.)
1 . Is this mass solid or cystic?
2 . What is its relationship to the tendon?
3 . What is the most likely diagnosis?
4. The histologic appearance of this lesion is identical to what other lesion?

Back 162

G iant Cell Tu mor of the Tendon S heath
1 . It is solid with internal vascularity.
2 . It is intimately associated with the tendon.
3. TIus is most likely a giant cell tumor of the tendon
sheath.
4. The appearance of this lesion is similar to
pigmented villonodular synovitis.
Reference
Middleton WD, Teefey SA, Boyer MI: Hand and wrist
sonography. Ultrasound Q 200 1 ; 1 7:2 1 -36.
Cross-Reference
Musculoskeletal Radiology: THE REQUISITES, pp 236-
238.
COl1l1llent
After ganglion cyst, giant cell tumor (GCn represents
the most common cause of a mass in the hand. Giant
cell tlUl10rs are a benign disorder of proliferative synovium
arising from the tendon sheaths. It is not clear if
they are reactive or neoplastiC. Histologically, giant cell
tumors of the tendon sheaths are identical to pigmented
villonodular synovitis. Giant cell tumors are most common
in 30- to 50-year-olds and are seen more often in
women than in men. They occur typically along the
volar surface of the first three fingers and are usually
isolated lesions. They are slow-growing and relatively
painless. Approximately 1 0% produce a pressure erosion
on the adjacent bone. The treatment of choice is surgical
resection. Approximately 20% recur following surgery.
Sonograplucally, giant cell tumors are solid, homogeneous,
hypoechoic masses located adjacent to tendons.
Frequently they partially surround the tendon. However,
because they arise from the sheath and not the tendon,
they do not move with the tendon when the finger is
flexed and extended. High frequency color Doppler
generally shows readily detectable internal blood flow.

Front 163

long itud inal views of the g a l l bladder in two patients.
1 . Describe the gallbladder abnormalities.
2. What is the significance of these abnormalities?
3. Are these findings common?
4. Would your diagnosis change if the sonographic Murphy's sign were negative?

Back 163

Gangrenous Cholecystitis
1 . The first image shows thickening of the gallbladder
wall, a focal area of mucosal ulceration along the
inferior margin, and a small region of
pericholecystic fluid. The second image shows
sloughed mucosal membranes .
2. Both patients have acute cholecystitis. The mucosal
ulceration and the sloughed membranes indicate
gallbladder wall necrosis.
3. Localized mucosal ulceration and sloughed
membranes are both rare.
4. Patients with gangrenous cholecystitis often have a
negative Murphy's sign.
Reference
Middleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1 993, pp 1 1 6- 1 42 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 4 1 -45.
Comment
Complications of acute cholecystitis include gallbladder
wall necrosis (manifested as mucosal ulceration, hemorrhage,
or desquamation) and perforation. Typical cases
of acute cholecystitis produce relatively uniform wall
thickening and gallbladder enlargement. As the disease
progresses, wall thickening may become more eccentric
and assume a layered appearance . As the mucosa starts
to break down, discontinuities may appear on sonography.
This is demonstrated i.n the first image. Bile or
blood may dissect under the mucosa and cause mucosal
desquamation into the gallbladder lumen. These
sloughed membranes are demonstrated on the second
itnage. Both of these findings are very uncommon, but
it is itnportant that they be recognized because they
itldicate gallbladder wall necrosis and gangrenous cholecystitis.
The perforation rate and mortality are both
higher in gangrenous cholecystitis, so these patients
require more urgent and aggressive care. Another sign
of gangrenous cholecystitis is a focal bulge in the gallbladder
wall. This is likely due to the combitled effects
of progressive itlcrease in intraluminal pressure and focal
weakening of the gallbladder wall. Actual perforation
of the gallbladder causes focal collections of fluid adjacent
to the gallbladder, often tracking up over the edge
of the liver or down into the right lower quadrant.
Small pericholecystic collections are usually due to focal
peritonitis and indicate more advanced disease but do
not itnply perforation.

Front 164

Transverse and longitudinal views of the testis .
l . Does this patient need further workup o r surgery?
2 . Is this lesion likely to be palpable?
3. What is a commonly associated lesion?
4. Is this condition usually unilateral or bilateral?

Back 164

Tu bular Ectasia of the Rete Testes
1 . The sonographic appearance is sufficiently specific
for tubular ectasia that it is not necessary to obtain
further workup or to perform surgery.
2 . 1\.lbular ectasia is not palpable.
3. Spermatoceles are commonly associated with
tubular ectasia.
4. 1\.lbular ectasia is usually bilateral, but it may be
very asymmetric.
Reference
Weitlgarten B], Kellman GM, Middleton WD, Gross ML:
1\.lbular ectasia within the mediastinum testiS . ] Ultrasound
Med 1 992 ; 1 1 : 349-3 5 3 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 438-439.
Comment
The rete testes are a complex collection of small tubules
that are located in the mediastinum of the testis. Fluid
from the semitliferous tubules drains into the rete testis
and then exits the rete testis via the efferent ductules.
The efferent ductules then converge into the head of
the epididymis.
Tubular ectasia of the rete testes is believed to be
caused by some degree of outflow obstruction of the
seminiferous fluid. Perhaps this is the reason that it is
frequently associated with testicular cysts and spermatoceles
of the epididymal head. It is also more commonly
seen itl patients with a history of inguinal surgery, such
as hernia repairs and vasectomies. Like testicular cysts,
tubular ectasia of the rete testes is more common in
elderly patients.
Normally, the tubules of the rete testes are so small
that they are not resolved as specific structures in the
mediastit1U1ll. However, when there is ectaSia, the tubules
can become resolved as small, fluid-filled, cystic
spaces. In most cases, the cystic spaces appear round
and do not take on a tubular appearance . When the
ectasia is mild, the bright refections from the back wall
of the fluid-filled tubules may be more prominent than
the cystic changes. When the ectasia becomes more
advanced, as itl this case, the cystic changes are the
predominant feature.
The key to maki.tlg the diagnosis and distitlguishing
tubular ectasia of ilie rete testes from cystic testicular
tumors is to note the bilateral involvement when present
and to recognize the elongated shape on long-aXiS
views of the testis.

Front 165

The fi rst i m age is a coronal magn ified color Doppler view of the aorta and
the left ren a l a rtery. The seco nd i m age is a transverse color Doppler view
of the left renal a rtery and a pulsed Doppler waveform. (See color plates .)
1. What is the upper limit of normal for renal artery peak systolic velocity?
2 . What is the normal ratio of renal artery to aortic peak systolic velocity?
3. How often are the renal arteries seen with ultrasound?
4. How common are accessory renal arteries?

Back 165

Increased Renal Artery Ve locity Due
to Arte rial Stenosis
1. The upper limit of normal fo r renal artery velocity
is 180 to 200 cm/sec.
2. The upper limit of normal fo r renal to aortic ratio is
3.0 to 3.5.
3. Visualization of renal arteries varies from report to
report, but the average is around 80% to 90%.
4. Approximately 20% of patients have an accessory
renal artery.
Reference
House MK, Dowling R], King P, Gibson RN: Using Doppler
sonography to reveal renal artery stenosis: An
evaluation of optimal imaging parameters. AJR Am J
Roentge nol I999; 173:761 -765 .
Cross-Reference
Ultrasound: THE REQ UISITES, pp 111-112.
Comment
Hypertension affects up to 60 million people in the
United States and is one of the most common diseases
in the world. Three-fourths of cases are mild and controlled
by diet and diuretics. Almost all of these patients
have primary hypertension. Severe hypertension that
is poorly controlled or controlled only with multiple
medications is more likely to be caused by a secondary
fa ctor such as renal artery stenosis (RAS). Although RAS
accounts fo r only 5% of the total number of patients
with hypertension, it is potentially curable. Therefore,
attempts at developing a noninvasive screening test that
can identify patients with RAS are important.
Doppler evaluation of the kidneys is one approach.
There are two basic ways that Doppler can detect RAS.
One is analogous to evaluation of the carotid arteries,
where an attempt is made at detecting elevated velocities
in the stenotic portion of the artery. Another is
detection of changes in the arterial waveform distal to
the stenosis.
In this case, the first image shows color Doppler
aliaSing at the origin of the left renal artery. This identifies
the site of maximum velocity. The waveform obtained
fro m this area yields a velocity of 290 cm/sec.
This clearly exceeds the upper limit of normal of 180
to 200 cm/sec and allows fo r a diagnosis of RAS.
The use of Doppler sonography in the evaluation of
suspected RAS is controversial. Based on my experience
through the late 1990s, I have come to the conclusion
that it is a valuable technique that can work in the
majority of patients. However, it takes a great deal of
experience and may not be appropriate fo r all practices.

Front 166

longitu d i n a l color Doppler views a n d corresponding pulsed Doppler
waveforms of the i nternal and external carotid a rteries. (See color plates.)
1 . In what direction is the flow in the external carotid artery?
2 . In what direction is the flow in the internal carotid artery?
3. What are the implications of these findings?
4 . What are the potential sources of flow in the external carotid artery?

Back 166

Common Carotid Occlusion
1. Flow in the external carotid artery CECA) is
reversed.
2. Flow in the internal carotid artery (lCA) is
antegrade.
3. This combination of findings occurs in patients
with occlusion of the common carotid artery (CCA)
when retrograde flow in the ECA provides collateral
flow to the ipsilateral ICA.
4. The ECA receives collateral flow fr om the ipsilateral
thyrocervical trunk (inferior thyroidal to superior
thyroidal), the ipsilateral vertebral artery (muscular
branches), and the contralateral ECA (ascending
pharyngeal, OCCipital, fa cial, and temporal).
Reference
Stasst ], Cavanaugh BC, Siegal TL, et al: US case of the
day: Occlusion of the CCA with segmental reversal
of ECA flow and a patent ICA. Radiographies
1995; 15: 1235- 1 238.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 470-477.
Comments
Occlusion of the CCA is an uncommon finding in populations
of symptomatic patients with extracranial carotid
artery disease. CCA occlusion is usually associated with
concomitant occlusion of the ipsilateral ICA and ECA.
As is shown in tlus case, in a minority of patients, the
vessels above the bifurcation can remain patent. When
this occurs, retrograde flow in the ECA crosses the
bifurcation to supply antegrade flow to the ICA. Since
the flow is supplied entirely by collaterals, the velocities
are low, and the arterial signals are blw1ted with a
parvus-tardus appearance. In addition, since the ECA is
now supplying the ICA and the brain, the waveform
from the ECA will appear sinillar to that of the ICA.
In the setting of a totally occluded CCA, detection of
a patent ICA has important clinical implications because
bypass procedures can be perfo rmed. Although Doppler
teclmiques are a reliable way of assessing patency of the
ICA, angiography is also necessary in the preoperative
evaluation of these patients in order to determine the
status of the aortic arch, the contralateral vessels, and
the intracranial vessels.

Front 167

Tran sverse grey-sca le view of the i nterpolar region of the right kidney
fo llowed by a power Doppler view at the same level. The two p u l sed
Doppler waveforms a re from seg mental a rteries supplyi ng the i nterpol a r
kidney and t h e u pper pole, respectively. (See color plates.)
1 . Describe the findings in the first two images.
2. Why is there such discrepant flow seen in the two waveforms?
3. How might this patient have presented?
4. What would you recommend be done next in this patient?

Back 167

Posttraumatic Renal Pseudoaneurysm
and Arte riovenous Fistula
1. The grey-scale view shows a complex fluid
collection arising from the right kidney. In addition,
there is a simple-appearing, round, cystic structure
within the otherwise complex collection. The
power Doppler view shows flow in the apparent
cyst. All of these findings are consistent with a
pseudoaneurysm and adjacent hematoma.
2. The increased flow to the interpolar region is not
explained by a simple pseudoaneurysm. There must
be an associated arteriovenous fistula.
3. Tills patient may have had trauma or a recent renal
biopsy and presented with flank pain and
hematuria.
4. The next test should be an arteriogram with
embolization.
Reference
Middleton WD, Kellman GM, Melson GL, Madrazo B:
Postbiopsy renal transplant arteriovenous fistulas:
Color Doppler US characteristics. Radiology
1989; 171 :253-257.
Cross-Reference
Ul trasound: THE REQ UISITES, pp 115-116.
Comment
Renal pseudoaneurysm cPA) occurs as a result of laceration
of an artery, usually from biopsy or penetrating
trauma, but also from blunt trauma. Arteriovenous fistulas
(AVF) may develop if there is coexistent injury to an
adjacent ve in. PA and AVF of the groin have both been
illustrated previously (case 63 and 130), and the same
principles apply in the kidney. Unfortunately, the classic
to-and-fro pattern of flow in a PA neck is much harder
to document in the kidney than in the groin because
the abnormality is so much deeper. Therefore , the diagnosis
of a PA is made based on detection of a cystic
lesion with blood flow throughout the cyst lumen. AJthough
a PA commU1llcates with the arterial system, the
typically narrow neck usually limits inflow and outflow.
In addition, the arterial flow jet that enters during systole
dissipates rapidly in the large lumen cavity. Therefo
re, waveforms fro m the PA lumen usually display low
velocity signals that are pulsatile but do not appear
classically arterial in nature unless the sample volume is
positioned close to the entering jet.
In this case, the waveform in the PA (not shown)
was a strong and large arterial signal. This suggests that
outflow, and correspondingly inflow, is brisk and should
raise the possibility of an associated AVF. Other clues
should then be sought. If an AVF is present, the arterial
182
flow to the segment of the kidney containing the AVF
should be increased compared to other normal segments.
This can be seen as a prominent supplying artery
on color Doppler and discrepant waveforms from the
different segments. In some cases, the draining vein
may also be apparent as an unusually prominent vessel.
Waveforms from the vein will show an inverted arterial
signal if the sample volume is placed close to the AVF.

Front 168

Transverse grey-scale and magnified color Doppler scan from a patient
with prostate carci noma. (T scan showed a single lesion in the l iver but
no other abnormalities. Bone scan was negative. (See color p lates.)
1. How likely is this liver lesion to be a prostate metastasis?
2. What other abnormalities should be considered?
3. What specific information would you like to know about this patient?
4. What else could be done to help establish the diagnosis?

Back 168

Ech inococcal Cyst
1 . A solitary hepatic metastasis from prostate
carcinoma in a patient with no evidence of
metastases elsewhere is very unusual, regardless of
the appearance of the lesion. In addition, the
organized appearance of the lesion and the
presence of calcification is very unusual for prostate
cancer.
2. Given the calcification, other considerations are an
old calcified hematoma or abscess, a calcified
metastasis from some other primary site, a
fibrolamellar hepatocellular cancer, or an
echinococcal cyst.
3. Given the possibility of metastases and
echinococcus, it is important to know whether the
patient had a history of a primary extrahepatic
malignancy other than prostate cancer or a history
of travel to a part of the world where echinococcus
is endemic.
4. Immunologic testing is often capable of establishing
the diagnosis of echinococcal disease. Fine-needle
aspiration biopsy is also acceptable . The latter was
performed in this patient.
Reference
Chehida FB, Gharbi HA, Hammou A, et al: Ultrasound
findings in hydatid cyst. Ultrasound Q 1 999;
1 5(4) : 2 1 6-222.
Cross-Reference
Ultrasound: THE REQUISITES, p I S .
Comment
A tapeworm, Echinococcus granulosus, usually causes
hydatid disease of the liver. The adult worm lives in the
intestine of the definitive host, usually a dog. Eggs are
excreted in the feces. The intermediate hosts, including
sheep, cattle, and humans, are infected by eating contaminated
plants and vegetables. Embryos travel from
the intestines of the intermediate hosts into the liver
and form cysts. The definitive host is infected when
cyst-containing organs of the intermediate host are
eaten.
In humans, the liver is the most commonly affected
organ, although the lungs, spleen, bones, kidneys and
central nervous system can also be affected. Cysts that
form in the liver have an external membrane called
the ectocyst and an internal, germinal layer called the
endocyst. In addition, there is a fibrous capsule formed
by the host around the cyst that is called the pericyst.
SonographicaJly, hydatid cysts may appear as relatively
simple cysts, as cysts with multiple internal daughter
cysts, as cysts with detached, floating endocystic
membranes, as cysts with internal debris, and as cysts
with internal or peripheral calcification.

Front 169

Longitudinal transvaginal views of the left ad nexa. The patient has a
remote history of a motor vehicle accident.
1. Describe the abnormality.
2 . Can this abnormality be related to the patient's history?
3. What else should be considered in the differential diagnosis?
4. How can the diagnosis be confirmed?

Back 169

S p lenosis
1 . The first itnage shows a homogeneous solid mass
separate from a normal left ovary. The second
image shows two sitniJar-appearing solid masses.
2. With a history of significant abdominal trauma, the
possibility of splenosis should be considered
whenever solid peritoneal masses are seen.
3. Peritoneal carcinomatosis and mesothelioma could
also have this appearance. Pedtmculated fibroids are
a common cause of solid extraovarian adnexal
masses, but it would be very unusual for them to
appear this echogenic, homogeneous, and uniform.
4. Splenosis can be confirmed with a damaged red
blood cell scan or a sulfur colloid scan.
Reference
Delama.rre J, Caopron JP, Drouard F, et al: Splenosis:
Ultrasound and CT findings in a case complicated
by an intraperitoneal inlplant traumatic hematoma.
Gastrointest Radiol 1 988; 1 3 : 275-278.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 47 - 1 48.
Comment
Splenic trauma can result in dissemination of splenic
tissue fragments to various parts of the body. These
fragments can implant, parasitize blood flow, and enlarge.
This is known as splenosis and may develop to
some degree in 20% to 60% of cases of splenic trauma.
The implants most often are located in the peritoneal
cavity, although they can also appear in the pleura,
pericardium, lung, retroperitoneum, and body wall. It
is very unusual for splenosis to cause symptoms, and
once the diagnosis is confirmed, treatment is rarely
needed.
The diagnosis should be suspected whenever tissue
sitnilar in echogenicity to the spleen is detected outside
the left upper quadrant in a patient with a history of
splenic injury. The implants are frequently multiple.
TIllS patient had other implants in the pelviS and in the
right upper quadrant. 'When the diagnosis is suspected,
it can be confirmed with heat damaged Tc99m-labeled
red blood cell scans or sulfur colloid scans.

Front 170

Color Doppler views of the kidney. (See color plates .)
1. Why is renal cortical flow better shown on the first image than on the second image?
2. Is the Doppler control that is responsible for the differences shown in the images a preprocessing or
a postprocessing control?
3. Should this control be adjusted to a higher level for a carotid examination or a testicular examination?
4. What is the primary purpose of this Doppler control?

Back 170

Effect of Color Priority on Color
Doppler I mages
1 . Blood flow is poorly seen on the second image
because the color priority is too low. The color
priority is indicated by a horizontal green line on
the grey-scale bar. Color is suppressed on any pixel
in the image that has a grey-scale value above that
line.
2. It is a postprocessing control, so it can be adjusted
even after the unage is frozen. In fact, the images
shown are actually the same image with the priority
set at different levels.
3. A higher setting would be more appropriate for a
testicular examination.
4. The purpose of the color priority is to eliminate
Doppler signals that are generated by electronic
noise or moving soft tissues.
Reference
Middleton WD: Color Doppler unage optimization and
interpretation. Ultrasound Q 1 998; 1 4 : 1 94-208.
Comment
In addition to the wall filter (case 1 25), another control
that is used to suppress color information is the color
priority. This parameter establishes a grey-scale pixel
value, above which color information is suppressed. It
is based on the assumption that blood flow should
only be demonstrated in blood vessels, and those blood
vessels should appear anechoic or very hypoechoic.
Therefore, any color assignment ariSing from a pixel
that is not anechoic or very hypoechoic must be due to
tissue motion or electronic noise.
When dealing with large or superficial vessels, such
as the carotids, these assumptions more or less apply,
and the color priority can be adjusted to mid greyscale
levels so as to prevent color assignment from
overwriting the grey-scale information arising from the
moderately echogenic pulsating vessel wall. However,
small vessels that are not resolvable on grey-scale (such
as parenchymal vessels in solid organs) have pixel echogenicity
values that are sunilar to the values of the soft
tissue arOlU1d them. If the color priority is set below
that tissue echogenicity, it is possible to completely
suppress color from real blood flow arising from within
those nomesolvable vessels. For this reason, the color
priority should be raised to the higher portions of the
grey-scale bar so that color suppression occurs only on
the very brightest pixels. In most situations, pre-set
scanning programs adjust the color priority so that it is
appropriate for the vessels being scanned. Nevertheless,
patient-to-patient variability sometimes makes it helpful
to increase the color priority in order to increase sensitivity,
or to decrease color priority in order to eliminate
unwanted color Signals.

Front 171

Long itud inal color Doppler view and pulsed Doppler waveform
of the epigastri u m at the level of the pancreas (pane), splenic vein (sv),
and celiac axis (ca) . (See color p lates.)
1. What vessel is seen draped over the celiac axis?
2. Is diameter or flow direction more important when evaluating this vessel?
3. In this case is either the diameter or the flow direction abnormal?
4. What diagnosis can be made based on these in1ages?

Back 171

Reversed Flow i n the Coronary Vein
1 . The vessel being imaged is the coronary vein.
2. The flow direction is more important than the
dianleter because Doppler can detect a change in
the flow direction before there is a change in the
vessel size.
3. In this case, the color assignment is blue and the
venous signal is below the base line, both
indicating flow away from the transducer. Given the
orientation of the vessel, tIllS also indicates flow
away from the SplelllC vein. Normally, flow in the
coronary vein is toward the splenic vein. The upper
limit of normal for coronary vein diameter is 6 nun,
and tIllS vessel is approximately 3 mm in diameter.
4. Reversed flow in the coronary vein is an indication
of portal hypertension.
Reference
Wachs berg RH, Sinunons MZ: Coronary vein diameter
and flow direction in patients with portal hypertension:
Evaluation with duplex sonography and correlation
with variceal bleeding. AJR Am J Roentgenot
1 994; 162 :637-64 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 9-22.
Comment
The coronary vein (left gastric vein) normally drains
venous flow from the lesser curvature of the stomach
and the gastroesophageal junction into the portal system.
The vein usually inserts near the confluence of the
portal and splenic veins. It is easiest to identify by taking
longitudinal views of the portal-splenic confluence and
100ki11g for a vessel that extends superiorly and to the
left. In most patients, the coronary vein drapes over the
celiac axis near the bifurcation into hepatic and splenic
arteries. Occasionally, the coronary vein passes beneath
the hepatic or splenic artery.
In normal patients, all veins that drain into the portal
system should have flow directed toward the portal vein
and the liver (llepatopetal flow). The coronary vein is
no exception. Reversal of flow in any of these veins
(llepatofugal flow) is a sign of portal hypertension. Because
the coronary vein is one of the most common
portosystenllc collaterals and is relatively easy to visualize
sonographically, it should be evaluated whenever
there is a question of portal hypertension.

Front 172

Long itud inal and tra nsverse views of the lower abdomen.
1. What congenital anomaly is demonstrated on these two images?
2. How rare is this abnormality?
3. To what does this abnormality predispose the patient?
4. Is there a gender preference?

Back 172

Horseshoe Kidney
1 . Horseshoe kidney.
2. This abnormality occurs in approximately one out
of every 500 births.
3. Patients are predisposed to urinary obstruction and
stone formation, and are at increased risk of renal
trauma. There may be an increased risk of Wilms'
tumor.
4. There is a slight male predominance.
Reference
Strauss S, Duchnitsky T, Peer A, et al: Sonographic features
of horseshoe kidney: Review of 34 patients. ]
Ultrasound Med 2000 ; 1 9 : 27-3 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 1 2 - 1 1 5 .
Comment
Horseshoe kidneys develop embryologically when there
is fusion across the midline of the metanephric blastema.
This almost always occurs in the lower pole region
and results in a U or horseshoe-shaped kidney. The
connection between the right and left lower poles is
usually a band of nmctioning renal parenchyma, although
a nonfunctioning fibrous band may be all that is
present. The band of connecting tissue is located anterior
to the aorta, immediately below the level of the
inferior mesenteric artery. Typically there are multiple
renal arteries, which may arise from the aorta, the common
iliac arteries, the internal iliac arteries, or the
inferior mesenteric artery.
The key to the diagnosis on sonography is detection
of the bridge of connecting parenchymal tissue. This
bridge appears as an oval-shaped hypoechoic structure
inunediately anterior to the aorta. Once this tissue is
detected, it is relatively easy to document during realtime
scanning that it connects to the lower pole of both
kidneys. Unfortunately, the bridging parenchyma is not
visualized unless a prospective search is made of the
preaortic region. Since tIlis is not a routine part of a
renal sonogram, horseshoe kidneys are easy to overlook.
To avoid overlooking tIlis condition, it is important to
recognize other clues to the diagnosis. The first clue
that a horseshoe kidney is present is typically unusual
difficulty in measuring renal lengths due to problems in
profiling the lower pole. In addition, the abnormal axis
of the kidneys, with the lower poles directed medial to
the upper poles, is a clue.
Typically there is no differential diagnosis. On an
isolated longitudinal view of the aorta, the parenchymal
band may be confused with preaortic lymphadenopathy
or other periaortic masses. Documentation of a COtUleCtion
to the lower poles of the kidneys elinlinates this
confusion.

Front 173

Views of the testis i n two patients.
1 . Describe the abnormality.
2 . What is the most likely diagnosis?
3. Is this a benign or a malignant condition?
4 . Is it associated with hormonal effects?

Back 173

Epidermoid Cyst
1 . The first image shows a solid-appearing mass with a
partially shadowing peripheral rim. The second
unage shows a solid-appearing mass with a
lamellated appearance.
2. Both of the appearances are very characteristic of
epidermoid cysts.
3. Epidermoid cysts are benign lesions.
4. Epidermoid cysts have no hormonal effects.
Reference
Moghe PK, Brady AP: Ultrasolmd of testicular epidermoid
cysts. BrJ Radial 1 999;72:942-94 5 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 439-440.
Comment
Epidermoid cysts of the testis are felt to be benign germ
cell neoplasms that can be thought of as mono dermal
teratomas with only ectodermal components. They are
rare, comprisulg less than 1 % of all testicular tumors.
Histologically they are composed of cystic spaces lined
by squamous epithelium and filled with yellowish-white
flaky-appearulg desquamated keratin. They manifest Ul
patients usually between 20 and 40 years of age as
painless masses that are often chronic Ul nature.
On sonography, epidermoid cysts appear as wellmarginated
lesions that are typically hypoechoic. They
may have a hyperechoic rim that completely or partially
shadows, and tllis appearance is very typical of an epidermoid
cyst. Another very typical appearance is a lamellated
arrangement of concentric rings like the cut
surface of an onion. In either case, the presumptive
diagnosis of epidermoid cyst should be made. Since
these findings are typical but not entirely diagnostic,
surgical exploration is still necessary to ensure that
the lesion is benign. However, in most cases a full
orchiectomy can be avoided in lieu of an enucleation of
the lesion.

Front 174

Transverse grey-scale and color Doppler view of the right
upper quadrant at the level of the renal h i l u m . (See color plates.)
1 . Describe the abnormality shown in this case.
2. Which renal vein is easiest to see in its entirety?
3. What alteration would you expect in the renal arterial flow?
4. Does detection of venous flow in the kidney exclude this diagnosis?

Back 174

Rena l Vei n Throm bosis
1 . The grey-scale image shows low-level echoes in the
renal vein. These echoes could be real or
artifactual. The color Doppler image shows flow
around a central filling defect, confirming the
presence of nonocclusive thrombosis.
2. The right renal vein is easier to see because it is
shorter, and the liver can be used as a window. The
left renal vein is longer and may be obscured by
bowel gas from the stomach or splenic flexure.
3. Many times the arterial waveforms will be normal.
If there is a change at all, the resistive index will
increase.
4. Most cases of renal vein thrombosis are associated
with persistent venous flow in the kidney and renal
hilum, so detection of venous flow canllot be used
to exclude the diagnosis.
Reference
Platt JF, Ellis JH, Rubin JM: Intrarenal arterial Doppler
sonography in the detection of renal vein tlu·ombosis
of the native kidney. AJR Am J Roentgenol 1 994;
162: 1 367-1 370.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 1 2 - 1 1 5 .
COffilDent
Renal vein thrombosis is an uncommon abnormality in
adults. Although it may be idiopathic, some type of
coagulopathy, such as diffuse intravascular coagulopathy
or collagen vascular disease, is usually present. Renal
vein thrombosis may also occur in the setting of membranoproliferative
glomerulonephritis and is associated
with the neplu'otic syndrome. It can also be due to
extension of clot from the inferior vena cava. The outcome
depends on the rapidity and completeness of
renal vein occlusion. Slowly progressive tlu'ombosis
allows for the development of venous collaterals, and
incomplete thrombosis allows for maintained venous
outflow so tl1at effects on the kidney may be absent or
minimal. On the other hand, complete and rapid thrombosis
results in hemorrhagic infarction of the kidney.
Bland renal vein thrombosis appears like venous
thrombosis anywhere else in the body. It produces an
intraluminal defect and may enlarge the caliber of the
vein. Thrombus may be hypoechoic or hyperechoic.
Detection of venous outflow from the renal hilum does
not exclude thrombosis because there may be persistent
flow at tltis level in patients with partial tlu'ombosis and
collateral outflow in cases of complete thromboSis. It is
also important to realize that in native kidneys, arterial
inflow may be affected only minin1ally. This likely is
related to venous collaterals that develop and provide
continued venous outflow despite venous thrombosis in
1 90
the main renal vein. In transplants, collateral flow is not
possible, so complete renal vein thrombosis results in
marked alteration in the arterial signal. Tltis usually
produces a classic to-and-fro pattern with pandiastolic
flow reversal

Front 175

Two transverse color Doppler views of the same testis. (See color plates.)
1. Why is more blood flow shown on the second unage?
2 . What is the relationship between the strength of reflection from small objects such as red blood cells
and the transmitted frequency?
3. What is the relationship between Doppler frequency shift and transmit frequency?
4. Under what circumstances would it be advantageous to drop the transmit frequency in order to
itnprove Doppler sensitivity?

Back 175

Effect of Tra nsmit Frequency on Doppler
Sensitivity
1 . The second inlage was obtained with a 7 MHz
transntit frequency and the first image with a 4
MHz frequency.
2 . Strength of reflection is proportional to the fourth
power of the transmitted frequency.
3. The Doppler frequency sltift is proportional to the
transmitted frequency.
4 . When imaging deep vessels, it is often helpful to
switch to a lower transmit frequency.
Reference
Middleton WD: Color Doppler image optintization and
interpretation. Ultrasound Q 1 998; 1 4 : 1 94-208.
Cross-Reference
Ultrasound: THE REQUISITES, P 467.
COffilDent
The Doppler equation is one of the few equations in
ultrasOlmd that is worth memorizing:
Fd = Ft X V X cose X 2 X 1 1C
Fd = Doppler frequency shift; Ft = Transmitted
frequency; V = Velocity of blood; e = Doppler angle;
C = Speed of sound. Since the Doppler frequency
shift is proportional to the transmitted frequency, ltigher
frequency transducers cause a h igher D oppler frequency
shift that is easier to detect.
More in1portantly, the strength of the reflection from
small objects such as red blood cells is proportional to
the fourth power of the transmitted frequency. Therefore,
higher frequency probes result in a stronger and
more easily detected reflection from red blood cells.
However, the improved sensitivity of ltigher frequency
probes is counterbalanced by their poor penetration
into deeper tissues. The net effect of transducer frequencies
is sometimes unpredictable. In cllitical practice,
it is a good idea to use a variety of different probes
operating at different frequencies whenever it becomes
difficult to detect flow in a given vessel. For deep applications,
it is often advantageous to switch to a lower
frequency probe, whereas ltigher frequency probes are
often better in superficial structures.

Front 176

Two sets of dual longitudinal i mages of the rotator cuff i n d ifferent
patients with right shoulder pain.
1. What is the diagnosis?
2 . Where does this abnormality most often occur?
3. Does this abnormality usually compress with transducer pressure?
4. Are bony changes typically associated with this abnormality?

Back 176

Partia l Th ickness Rotator Cuff Tear
1 . Partial thickness rotator cuff tear.
2. Partial thickness tears most often occur along the
deep surface of the supraspinatus insertion.
3. Partial thickness tears usually do not compress.
4. Bony pitting and irregularity is usually associated
with partial thickness tears.
Reference
VanHolsbeeck MT, Kolowich PA, Eyler WR, et al: US
depiction of partial thickness tear of the rotator cuff.
Radiology 1 995; 1 97:443-446.
Cross-Reference
Ultrasound: THE REQUISITES, pp 455-457.
Comment
Tears of the rotator cuff can be divided into full thickness
and partial thickness tears. Partial thickness tears
are tears that do not extend all the way from the deep
to the superficial surface of the cuff. They can involve
either the deep surface, the superficial surface, or the
internal aspect of the cuff. However, the majority arise
from the deep surface and involve the supraspinatus
tendon insertion.
The sonographic appearance of a partial thickness
tear consists of a hypoechoic defect that remains constant
despite changes in the orientation of the transducer.
In most cases, there is also a bright reflector
associated with the hypoechoic area. As with full thickness
tears, the underlying bony cortex is usually irregular.
Unlike full thickness tears, partial thickness tears are
not associated with contour changes of the peribursal
fat. In addition, partial thickness tears do not compress
with transducer pressure.
Partial thickness tears must be distinguished from
tendon anisotropy, which normally causes the deep surface
of the supraspinatus insertion to appear hypoechoic.
Tendon anisotropy usually becomes more echogerlic
when the transducer is angled upward, whereas
the echogenicity of partial tears does not change. Tendon
anisotropy is usually poorly marginated, while partial
tears are better marginated. Finally, tendon anisotropy
is usually entirely hypoechoic, whereas partial
tears usually have at least a small hyperechoic component.
The reported sonographic sensitivity in detecting partial
thickness tears is good, with two studies indicating
a range of 93% to 96%. However, not everyone has had
this degree of success, and it is clear that partial thickness
tears are not as easy to identify as full thickness
tears, and the criteria for partial thickness tears are less
well studied. Unlike full thickness tears, partial tears are
not treated with surgery unless patients fail a course of
conservative management first. Therefore, the implication
for missing a partial thickness tear is less than that
for missing a full thickness tear.

Front 177

Transverse and longitudinal views of the right lobe of the thyroid
in a patient with neck pain.
1 . Describe the abnormality.
2 . Would you expect this abnormality to resolve completely, resolve partially, or persist with medical
therapy?
3. If this patient did not have neck pain, what else would you include in the differential diagnosis?
4. What is the most common type of thyroid cancer?

Back 177

Subacute Thyroiditis
1 . The abnormality consists of a focal, poorly
marginated, hypoechoic lesion in the mid right
thyroid. In a patient with pain, tllis is highly
suggestive of subacute thyroiditis.
2. With appropriate therapy, the sonographic findings
should completely resolve.
3. If this patient did not have pain, thyroid cancer
should be considered.
4. The most conunon type of thyroid cancer is
papillary.
Reference
Ahuja AT, Metreweli C: Ultrasound of thyroid nodules.
Ultrasound Q 2000 ; 1 6 : 1 1 1 - 1 2 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 448-45 1 .
Comment
The sonographic appearance in tllis case is nonspecific.
Nevertheless, in a patient with the appropriate clinical
presentation, the appearance is very typical of subacute
granulomatous thyroiditis (also called de Quervain's thyroiditis).
Subacute granulomatous thyroiditis is felt to be
due to a viral infection. It occurs more often in women
and produces an enlarged and painful thyroid and often
a fever. It is often preceded by an upper respiratory
infection. The entire gland may be involved, or involvement
may be focal. Transient hyperthyroidism may be
seen in the illitial stages of the disease owing to follicular
rupture. Tllis transient hyperthyroidism may be followed
by a transient phase of hypothyroidism. The process
is usually diagnosed cfulically and responds well to
medical treatment. When sonography is performed, it
typically shows a poorly marginated area of decreased
echogenicity ill the involved region of the thyrOid. Blood
flow to the area is typically normal or decreased.

Front 178

G rey-scale and Doppler views of the kidney i n a patient with hypertension.
1. What is the abnormality?
2 . Where is the abnormality likely to be located?
3. What is the name given to this entity?
4. What are some of the potential etiologies?

Back 178

Page Kidney
1 . Fluid surrounding part of the kidney. The Doppler
waveform shows decreased diastolic flow, with an
elevated resistive index of 0.78. This suggests
compression of the kidney.
2. Given the location on grey-scale scanning and the
compression suggested by the increased resistive
index, tills lesion is almost certainly in the
subcapsular space.
3. This entity is known as Page kidney.
4. Prior biopsy or other percutaneous intervention,
recent lithotripsy, anticoagulation, bleeding from a
tumor, and trauma are potential etiologies. This
patient presented with hypertension following
lithotripsy.
Reference
Chamorro HA, Forbes Tw, Padowsky GO, Wholey MH:
Multiinlaging approach in the diagnosis of Page kidney.
A]R Am ] Roentgenol 1 98 1 ; 1 36:620-62 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 06- 1 09.
Comment
In 1 939, Page demonstrated that wrapping a kidney
in cellophane could create hypertension. The resulting
perineplu-itis caused compression of the kidney and
altered the intrarenal hemodynamicS such that ischemia
developed. Activation of the renin-angiotensin-aldosterone
system then resulted in hypertension. It was subsequently
shown that a subcapsular hematoma could produce
similar compression and could cause hypertension
via the same mechanism.
Hemorrhage into the subcapsular space undergoes
the same evolution that hemorrhage undergoes elsewhere
in the body. In the acute period it appears echogenic.
Over time, as the clot lyses and liquefies, the
hematoma becomes more complex-appearing, with
both cystic and solid areas. With more time, the hematoma
becomes entirely liquefied and appears as a simple
collection of fluid.
In the acute phase, subcapsular hematomas can be
very difficult to appreciate sonographically. In most
cases, the kidney looks very distorted and the normal
renal architecture may be completely obliterated. This
is partially due to compression of the kidney by the
contained hematoma and partially due to the difficulty
in determining where the hematoma stops and the kidney
starts. In the latter regard, color Doppler can be
helpful in distinguishing the vascular renal parenchyma
from the avascular hematoma. Careful grey-scale inspection
can usually find the interface between the kidney
and the hematoma once the possibility of a subcapsular
hematoma has been considered.

Front 179

Transverse views of the left l o be of the l iver and of the proximal abdom inal aorta in two
patients.
1 . What artifact is present on both of these images?
2 . What causes this artifact?
3. How can this artifact be eliminated?
4. Does sound travel faster in fat or in soft tissue?

Back 179

Midline Refraction Artifact
1 . These images illustrate refraction artifact from the
rectus muscles causing a duplication of a hepatic
hemangioma and causing apparent widening and
dissection of the aorta.
2. The rectus muscles act as an acoustic lens so that
sound is bent and structures are inappropriately
localized and duplicated on the image.
3 . Tlus artifact can be eliminated by scanning with the
transducer to the side of the midline, away from the
edge of the rectus muscle.
4. Sound travels faster in soft tissue than in fat.
Reference
Ziskin MC: Ftmdamental physics of ultrasound and its
propagation in tissue. Radiographies 1 993 ; 1 3: 1 05-
709.
Comment
Sound waves bend when passing obliquely through an
interface between two substances that transn1it sound
at different speeds. This is called refraction and is analogous
to redirection of light by an optical lens. Since the
speed of sound is least in fat (approximately 1 450
m/sec) and greatest in soft tissues (approximately 1 540
m/sec), refraction artifacts are most prominent at fat-soft
tissue interfaces. The most widely recogluzed refraction
artifact occurs at the junction of the rectus abdominis
muscle and adjacent abdominal wall fat. Since the ultrasound
computer assumes that sound travels in a straight
line, structures that produce echoes after the sOtmd
pulse has been refracted will be incorrectly localized on
the image. In fact, structures are typically duplicated
because they reflect not only the sound pulse that has
been refracted but also a sound pulse that has not
been refracted. The end result is a duplication of deep
abdominal and pelvic structures seen when scanning
transversely through the abdominal midline.
Soft tissue and fluid interfaces can also produce refraction
artifacts because the speed of sound in body
fluids ( 1 480 m/sec) is slower than in soft tissues. Tlus
can produce duplication of structures deep to the refracting
interface just as with soft tissue-fat interfaces.

Front 180

Pulsed Doppler waveforms from the left and right kidneys.
1 . Which renal arterial waveform is abnormal?
2 . What is a normal early systolic acceleration?
3. How severe must this condition be before acceleration values drop?
4 . What term is used to describe the abnormal waveform shown in this case?

Back 180

Blunted I ntrarenal Artery Waveform Due
to Renal Artery Stenosis
1 . Neither waveform is normal. The first waveform
shows a low systolic acceleration indicative of
proximal arterial stenosis. The second shows
diminished diastolic flow due to renal parenchymal
disease.
2. A normal early systolic acceleration is greater than
3 m/sec2.
3. Probably somewhere between 60% and 80%
diameter stenosis.
4. A blunted arterial waveform is also called a parvustardus
waveform.
Reference
Stavros T, Harshfield D : Renal Doppler, renal artery
stenosis, and renovascular hypertension: Direct and
indirect duplex sonographic abnormalities in patients
with renal artery stenosis. Ultrasound Q 1 994;
2(4) : 2 1 7-263.
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 1 1 - 1 1 2 .
Conunent
A great deal of interest has been focused on the detection
of renal artery stenosis in patients with hypertension.
There are two basic ways to detect this abnormality
using Doppler analysis. One involves evaluation of
the arterial waveforms in the segmental or interlobar
arteries of the kidney. The effects of a proximal stenosis
have long been recognized in clinical medicine, and all
medical students learn to feel the distal pulses for parvus-
tardus effects in patients with aortic valve stenosis.
ParVlls tardus refers to decreased' amplitude of the pulse
and delayed tinle to reach the peak.
These same parvus-tardus effects can be seen in the
Doppler waveform distal to a stenosis . Normally, the
early systolic upstroke is extremely rapid. In patients
with a proximal stenosis, the upstroke is slower. This
can be quantified by determining the early systolic acceleration.
Acceleration is defined as the change in velocity
divided by the change in time. Both of these
values can be obtained on an angle-corrected Doppler
waveform by simply placing a cursor at the early and
late points of the systolic upstroke.
Another effect of a proximal stenosis is a decreased
systolic peak. This is harder to measure on an absolute
basis but can be recognized by noting a relative change
in the systolic peak compared to the diastolic flow. This
change in the systolic peak compared to the diastolic
flow can be quantitated with the resistive index. Since
systole is reduced to a greater extent than diastole, the
resistive index goes down. Therefore, asymmetry in renal
resistive indexes is another way of identifying renal
artery stenosis.

Front 181

Tra nsverse view of the anterio r left shoulder and similar d u a l com pa rison
views of the right and left shoulders.
1 . Describe the abnormality.
2 . What other abnormality would you expect in this patient?
3. Identify the greater and lesser tuberosity on the first image .

Back 181

Biceps Tendon Dislocation
1. The biceps tendon groove is empty on the left, and
the tendon is located anterior to the lesser
tuberosity.
2 . Patients with biceps tendon dislocation/subluxation
almost always have an associated rotator cuff tear.
3 . The lesser tuberosity forms the medial edge of the
biceps tendon groove, and the greater tuberosity
forms the lateral edge. The biceps tendon always
dislocates medially. In this view, the lesser
tuberosity is the tuberosity immediately posterior to
the dislocated biceps tendon.
Reference
Middleton WD, Teefey SA, Yamaguchi K: Sonography of
the shoulder. Semin Musculoskeletal Radiol 1 998;
2 : 2 1 1 -22 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 455-457.
Conunent
The biceps tendon is normally secured in the biceps
tendon groove by the transverse humeral ligament and
several extensions of tissue from the supraspinatus and
the subscapularis tendons. With proper transducer angulation
(perpendicular to the long axis of the tendon),
the biceps tendon appears as an echogenic ovoid structure
in the groove. If the tendon cannot be seen in
the groove, then it is either torn or dislocated, or the
transducer is not angled properly. These possibilities
can be distinguished by identifying the tendon inferiorly
and following it superiorly. If it is intact but dislocated,
the more superior tendon is seen medial to the tendon
groove. It may be located anterior to the lesser tuberosity,
as in tlllS case, or medial to the lesser tuberosity.
Whenever there is a dislocated biceps tendon, it is
very likely that there is an associated rotator cuff tear.
When the tendon is just anterior to the lesser tuberosity,
most likely there is a supraspinatus tear. When the
tendon dislocates medial to the lesser tuberosity, there
is usually a subscapularis tear.

Front 182

Longitudina l views of the i nternal carotid artery. (See color pl ates.)
1 . Based on the diff erent Doppler angle in the two images above, in which image would you expect the
frequency shifts from the internal carotid artery to be higher?
2 . Why is the internal carotid blood flow harder to detect in the first image than in the second image?
3. Is the effect responsible for the differences in these images more noticeable on linear arrays or on
curved arrays?
4. When using a phased array transducer, is it better to perform Doppler analysis in the center of the
sector or at the edge of the sector?

Back 182

Effect of Beam Steering on Doppler
Sensitivity
1 . In the first image, the beam is steered to the left so
that the Doppler angle is lower. This results in a
higher frequency shift from the internal carotid
artery.
2 . Despite the higher frequency shifts, sensitivity in
the first image is reduced because of the beam
steering. In the second image, the beam is directed
straight down, and sensitivity improves even though
there is a less favorable Doppler angle.
3. Electronic beam steering is performed on linear
array transducers but not on Clu'ved array
transducers, so the effect is only present on linear
array images.
4. With phased array transducers, there is less beam
steering in the center of the unage, so it is better to
perform Doppler analysis in the center, provided
other angle effects are equivalent.
Reference
Middleton WD: Color Doppler image optimization and
interpretation. Ultrasound Q 1 998; 1 4 : 1 94 -208.
Comment
In the images shown in this case, the angle between
the carotid artery and the transmitted Doppler pulse is
greater (Le., closer to 90 degrees) in the second image.
Because of tIllS, the blood flow in the internal carotid
artery produces a smaller frequency shift in the second
unage and a larger shift in the first image. Consequently,
it would seem to make sense that flow would be easier
to detect in the first unage. However, this is not the
case because the transmitted Doppler pulse was steered
to the left in the first image and was not steered Ul the
second image,
Beam steering is a control that is more or less userselectable.
Whenever the Doppler pulse is du'ected at
an angle other than perpendicular to the transducer
surface, it is beulg electronically steered. TIllS occurs
whenever color Doppler is performed at the edge of
the sector image with a phased array transducer, Beam
steerulg is also a color and pulsed Doppler option on
most linear array transducers. Whenever the Doppler
beam is steered, it loses some of its focusing capabilities,
and the transnlltted pulse loses a greater percentage of
its energy to side lobes. In addition, when the transmitted
pulse is steered, the echo returns to the transducer
at an angle. This produces less of an effect on the
crystals and a weaker electrolllC impulse than when the
echo returns at 90 degrees (analogous to the different
force exerted on a billiard table cushion when a ball
strikes the cusillon at an angle compared to striking the
1 98
cusillon head-on). Thus, for a variety of reasons, signal
strength is less when the Doppler beam is steered.
With color Doppler, the decreased signal strength
may result in a loss of sensitivity sufficient enough to
cause a false-positive diagnosis of vessel occlusion.
Therefore, adjustment of Doppler beam steerulg must
take U1to account the sometunes conflicting effects of
different Doppler angles on the frequency shift as well
as the signal strength.

Front 183

Transverse color Doppler views of the outflow vei n from a d i a lysis fistula.
(See color plates.)
1 . Is aliaSing present on these views?
2 . Explain the color assignment on these linages .
3. Why did the distribution o f red and blue color assignment change when the Doppler pulse was
steered to the right in the second linage?
4 . How accurate would you expect pulsed Doppler velocity determinations to be in this vessel?

Back 183

Helical Flow
1 . Aliasulg is not present. The interface between red
and blue in the middle of the vessel is in the dark
shades, corresponding to low frequency sl1ifts. This
indicates a change Ul direction rather than aliaSing.
2. Helical flow is present in the vessel, so that one
half of the vessel has flow toward the transducer
and the other half has flow away from the
transducer.
3. When the Doppler pulse was steered at an angle,
the division between blood flowing toward the
pulse and blood flowulg away from the pulse
clunged.
4. Pulsed Doppler velocity determinations are not
accurate because flow is not parallel to the long
axis of the vessel, and determination of true flow
direction is impOSSible. Thus, determination of the
true Doppler angle is not possible
Reference
Middleton WD: Color Doppler image optinlization and
interpretation . Ultrasound Q 1 998; 1 4 : 1 94-208.
Comment
We often assume that the blood flow in a vessel more
or less travels Ul a straight line along the long axis of
that vessel. In general this is true. However, there are
some situations where flow is not directly straight and
parallel to the axis of the vessel . In such cases, it is
possible to misinterpret the direction of flow. TillS occurs
most dramatically when there is helical flow in a
vessel. With helical flow, the flow spirals in the artery
in one overall axial direction. But in one half of the
vessel, the flow is toward the transnlltted Doppler pulse,
and in the other half the flow is away from the Doppler
pulse. As shown in this case, helical flow can produce
the appearance of simultaneous flow in one direction
Ul one half of the vessel and in the opposite direction
Ul the other half of the vessel.

Front 184

Longitudinal views of the i nferior vena cava and the aorta
in two patients.
1 . What normal variants are shown in these views of the aorta and the inferior vena cava?
2 . How common are these variants?
3. Which is seen most often on sonography?

Back 184

Renal Vascular Va riants
1. The first image shows two right renal arteries
located behind the inferior vena cava. The second
image shows a retroaortic left renal vein.
2. Duplicated renal arteries occur in approximately
20% to 30% of the population. A retroaortic left
renal vein occurs as an isolated finding in
approximately 2% of the population and as part of a
circumaortic left renal vein in approximately 10%.
3. It is much easier to see duplicated right renal
arteries on sonography. Retroaortic renal veins are
typically collapsed and harder to visualize with
ultras ound.
Reference
Cho KJ , Thornbury JR, Prince MR: Renal arteries and
veins: Normal variants. In Pollack HM, McClelU1an
BL, Dyer RB, Kenney PJ (eds): Cl inical Ur ography,
2nd ed. Philadelphia, WE Saunders, 2000, pp 2476-
2489.
Cross-Reference
Genitourinary Radiology: THE REQ UISITES, pp 55-59.
Comment
Multiple renal arteries are common. They usually arise
from the aorta near the main renal artery. However,
they occasiona lly arise significantly lower on the aorta
and rarely from the common iliac arteries. Accessory
renal arteries can enter the kidneys either tlu'ough the
renal hilum or directly through the renal parenchyma.
Many accessory renal arteries are not detected with
sonography. This is especially true of accessory left renal
arteries. However, accessory right renal arteries that
arise fr om the aorta near the main renal artery are
relatively easy to see. As tIlis case demonstrates, when
accessory right renal arteries are present, longitudinal
views of the inferior vena cava show two round structures
behind the inferior vena cava and in fr ont of the
right diaphragmatic crus. Doppler analysis can be used
to confirm the arterial nature of these structures.
Retroaortic left renal veins are another common renal
vascular variant. Like accessory renal arteries, they are
easily overlooked on sonography. Normally there are no
vascular structures located between the abdominal aorta
and the spine. When present, a retroaortic left renal
vein appears as a vascular structure communicating
with the inferior vena cava and passing posterior to the
aorta. On longitudinal scans it appears as an anechoic
or hyp oechoic oval-shaped structure behind the aorta,
as shown in tllis case. It is usually associated with a
normally located left renal vein (I.e., a vein that passes
between the superior mesenteric vein and the aorta)
and in such a case is termed a circumaortic left renal
vein.

Front 185

Transverse and longitudinal views of the posterior tibial
tendo n (cursors) .
1 . Describe the findings.
2 . What three tendons are located posterior to the medial malleolus?
3. What two tendons are located posterior to the lateral malleolus?
4. Which of these tendons is most likely to be affected like this?

Back 185

Partial Longitudinal Te ndon Te ar
1. An elongated, hypoechoic defect along the long
axis of the tendon is seen on the longitudinal view,
and a central defect is seen on the transverse view.
2. The three tendons are the Posterior Tibial, the
flexor Digitorum longus, and the flexor Hallucis
longus. Mnemonic-Tom, Dick, and Harry.
3. The peroneus longus and brevis tendons are located
posterior to the lateral malleolus.
4. The posterior tibial tendon is the most likely to
develop partial tears such as this one.
References
Fessell DP, Vanderschueren GM, Jacobson JA, et al: US
of the ankle: Te chnique, anatomy, and diagnosis of
pathologic conditions. Radiograp hies 1998; 18:325-
340.
Wa itches GM, Rockett M, Brage M, Sudakoff G: Ultrasonographic-
surgical correlation of ankle tendon
tears. ] Ultrasound Med 1998; 17:249-256.
Cross-Refe rence
Ultraso und: THE REQUISITES, pp 455-456.
Comment
The normal posterior tibial tendon runs immediately
posterior and then inferior to the medial malleolus. It
passes into the foot and fans out to insert on the navicular
as well as on the cuneiforms and the proximal
metatarsals of the second, third, and fo urth toes. Immediately
posterior to the posterior tibial tendon is the
flexor digitorum longus tendon. Further posterior and
medial is the flexor hallucis longus. Like other tendons,
these three tendons have a fibrillar echo pattern that
varies in echogenicity depending on the angle between
them and the sound pulse.
The scans that are shown in this case demonstrate a
fo cal, elongated hyp oechoic area within an enlarged
posterior tibial tendon. Tllis is the typical appearance
of a partial tear. Sonography is an .::xcellent means of
diagnosing tears of the ankle t

Front 186

Tra nsverse and longitudinal views of the g a l l bladder i n two patients.
1 . Describe the abnormal findings in these images.
2. Do gallstones cause this condition?
3. What is the treatment of choice?
4. What is the characteristic pathologic finding in this condition?

Back 186

Adenomyomatosis of the G a l l bladder
1. The first image shows gallbladder wall thickening
and several short, bright comet-tail artifacts arising
from the gallbladder wall. The second image shows
a fundal mass that contains multiple internal cystiC
spaces. All of these findings are seen in
adenomyomatosis.
2. This condition is not caused by gallstones.
3. No treatment is required. This is generally an
asymptomatic condition.
4. The characteristic finding on pathology is
Rokitans1..],-Aschoff sinuses.
Reference
Raghavendra BN, Subramanyam BR, Balthazar EJ, et al:
Sonography of adenomyomatosis of the gallbladder:
Radiologic-pathologic correlation. Radiology 1 983;
1 46:747-752.
Cross-Reference
Ultrasound: THE REQUISITES, pp 48-49.
Comment
Adenomyomatosis is a hyperplastic condition of the
gallbladder wall. It is characterized by small mucosal
diverticula that protrude into a thickened layer of muscle.
The mucosal diverticula are called RokitanskyAschoff
sinuses. Adenomyomatosis is not related to gallstones
and occurs equally in men and women. It is a
benign condition with no malignant potential.
Adenomyomatosis occurs in three forms. It can involve
the gallbladder diffusely, segmentally, or focally.
The diffuse form may or may not cause enough wall
thickening to be detected on sonography. The segmental
form of adenomyomatosis causes an alllular region
of wall thickening that may separate the lumen into two
diff erent compartments. In such cases, bile stasis in the
fundal compartment predisposes to gallstone formation.
The focal form most often appears as a mass in the
gallbladder fundus. Although the Rokitansky-Aschoff sinuses
are well visualized as cystic spaces in the second
image, they are usually too small to be resolved. However,
it is not uncommon for cholesterol crystals to
accumulate in the Rokitansky-Aschoff sinuses, and these
crystals are frequently associated with comet-tail artifacts
that can be seen sonographically.
In most cases, the diagnosis of adenomyomatosis can
be made with confidence based on the sonographic
findings. When there is extensive wall thickening and
the characteristic comet-tail artifacts or RokitanskyAschoff
sinuses are not seen, the possibility of gallbladder
cancer should also be considered. In such cases, an
oral cholecystogram may be helpful to better visualize
the Rokitansky-Aschoff sinuses and thus confirm the
diagnosis of adenomyomatosis.

Front 187

longitudinal views of the kid n ey in two patients.
1. Describe the abnormality in these kidneys.
2 . What are the two major conditions that should be considered in the differential diagnosis?
3. How is it possible to distinguish these conditions?
4. What is the origin of the abnormality shown in this case?

Back 187

Peri pelvic Cysts S i m u l ating Hyd roneph rosis
1. Both images show fluid-filled structures separating
the renal sinuses.
2. The differential diagnosis is hydronephrosis and
peripelvic cysts.
3. Look for cOl1llmnication between the fluid-filled
structures and each other and with the renal pelvis.
4. Peripelvic cysts are believed to be lymphatic in
origin.
Reference
Koelliker SL, Cronan JJ: Acute urinary tract obstruction:
Imaging update. Urol Clin North Am 1 997;24: 57 1 -
582.
Cross-Reference
Ultrasound: THE REQUISITES, pp 85-86.
Comment
A number of abnormalities can simulate hydronephrosis.
Perhaps the most common is peripelvic cysts. These
cysts are believed to be congenital and arise from lymphatics
in the renal sinus. Although they are filled with
simple fluid, it is generally more difficult to clear them
out of all internal echoes than it is to clear simple
cortical cysts. They may be single, but they are often
multiple. Single cysts are usually easy to diagnose with
sonography. When multiple peripelvic cysts are present,
they may become elongated and ovoid and herniate out
into the renal hilum. Under these conditions, they are
often mistaken for hydronephrosis.
The best way to distinguish multiple peripelvic cysts
from hydronephrosis is to obtain a coronal view. In such
a view, true hydronephrosis usually appears very typical,
with a dilated renal pelvis that extends into dilated
infundibulae that extend into the upper, mid, and lower
zones of the kidney. With peripelvic cysts, this typical
appearance is lacking. Whenever there is doubt, intravenous
urography is a good method to distinguish between
the two possibilities. If the patient has renal
dysfunction, gadolinium-enhanced MRI or nuclear scintigraphy
can be used.

Front 188

Longitudinal grey-scale view of the su perficial femoral vein i n one
patient and longitudinal co lor Doppler view of the su perficial femoral
artery and vein in a nother patient. (See color plates.)
1 . What is the abnormality in these two different patients with the same condition?
2 . What is the significance of these findings?
3. Is clot echogenicity a reliable way of distinguishing acute from chronic deep vein thrombosis CDVD?
4 . Is vein diameter a reliable way to distinguish acute from chronic DVT?

Back 188

C h ronic Deep Vei n Thrombosis
1. On grey-scale imaging, normal vein walls are so thin
that they are visualized as an echogenic interface
with no measurable thickness. In this case, the
grey-scale image shows a wall that is easily
resolvable. On color Doppler, normal venous blood
flow is seen as a single channel of color extending
from one wall to the other wall. In this case,
multiple irregular channels are present in the lumen
of the vein.
2. Both of these findings represent chronic changes
from prior episodes of acute deep vein thrombosis
(DVn.
3. Acute tlu'ombus tends to be hypoechoic, and
chronic thrombus tends to be more echogenic.
However, there is a moderate amount of overlap, so
that echogenicity is not a useful way to determine
the age of the clot.
4. Acute DVT often expands the lumen of the vein.
The lumen is usually contracted or normal with
chronic DVT. As with echogenicity, there is enough
overlap between acute and chronic DVT that vein
diameter is not a reliable distinguishing
characteristic.
Reference
Cronan JJ, Leen V: Recurrent deep venous thrombosis:
Limitations of US. Radiology 1 989; 1 70:739-742.
Cross-Reference
Ultrasound: THE REQUISITES, pp 483-485.
Comment
Following an episode of acute DVT, clot may resolve in
several ways. In the fortunate patient, it will completely
resolve, and the vein will return to a normal appearance
and normal function. Tllis occurs in approximately 60%
of patients, most often when the thrombosis is relatively
linlited to begin with. In less fortunate patients, clot
resorption leaves various sequelae that may compromise
valvular function and lead to the postpWebitic syndrome.
One sequela is a focal eccentric t1lickelling of
the vein wall. Another is diffuse tllickening of the vein
wall, occasionally with associated wall calcification. A
third change is development of irregular channels
within the partially recanalized vein lumen. These
changes usually occur and stabilize within 6 months of
the initial tlu·ombosis. Since these clu'onic changes can
be difficult to distinguish from acute changes, some
experts advocate a repeat ultrasound after 6 months in
order to establish a new base line. TIlis type of comparison
scan can be extremely valuable when the patient
returns with recurrent symptoms and the question of
acute versus chronic DVT is raised

Front 189

Longitudinal grey-scale view of and color Doppler view and pulsed
Doppler waveform from the portal vein. (See color plates.)
1 . What is the significance of an expanded portal vein lumen filled with echogenic material?
2. What is the significance of the vascularity shown on the color Doppler image?
3. What is the most likely etiology of this abnormality?
4. Is it safe to biopsy an abnormality such as this?

Back 189

Tu mor Thrombus in the Portal Vein
1 . Echogenic material within the portal vein indicates
venous thrombosis. When the lumen is expanded
by the thrombus, it is much more likely to be
tumor t1u'ombus than bland tlu-ombus.
2. Detection of internal vascularity within a portal
vein tlu-ombus indicates that the thrombus is
vascularized tissue and is not bland thrombus. This
represents a sign of tumor invasion of the portal
vein.
3 . The most common cause of tumor thrombus in the
portal vein is hepatocellular cancer. Other
possibilities include metastatic disease of the liver,
cholangiocarcinoma, and islet cell tumors of the
pancreas.
4. Biopsy of portal vein thrombus is safe and can
Simultaneously establish the diagnosis as well as the
stage of the tumor.
Reference
Dodd GD III, Memel DS, Baron RL, et al: Portal vein
thrombosis in patients with cirrhosis: Does sonograpllic
detection of intrathrombus flow allow differentiation
of benign and malignant thrombus? AJR A m
J Roentgenol 1 995; 1 6 5 : 573.
Cross-Reference
Ultrasound: THE REQUISITES, P 24.
Comment
Up to 30% of hepatocellular carcinomas invade the portal
veins. The thrombus starts in the peripheral veins
and then grows into the more central portal veins. As
the tlu'ombus grows toward the central portal veins, it
drags its arterial supply with it. For tllis reason, the
arterial flow in tumor thrombus is usually in the opposite
direction as the portal venous flow. In some patients,
it is relatively easy to see the internal blood
vessels in tumor tlu-ombus on color Doppler and to
obtain an arterial signal on pulsed Doppler. However, in
other patients this may not be possible. Therefore, inability
to detect internal Doppler signals does not necessarily
mean that the tlu'ombus is bland. Certain greyscale
findings can also be helpful. Tumor thrombus
often expands the lumen of the portal vein, while bland
thrombus rarely does. In addition, tumor tiu-ombus may
contain small cystic spaces, and this is uncollUnon in
bland tlu-ombus.
When it is necessary to obtain a tissue diagnosis in a
patient with suspected hepatocellular carcinoma and
tumor tlu'ombus, it is safe to biopsy the thrombus in
the portal vein. At our institution, this is done as a fineneedle
aspiration with a 22- to 25-gauge needle.

Front 190

Lo ng itud inal views of the right kid n ey in two patients.
1 . What is the likely etiology of the cysts in these patients' kidneys?
2. Are these patients at increased risk for renal tumors?
3. Will renal transplantation alter the natural history of this condition?
4. Are cysts more likely in other organs?

Back 190

Acq u i red Cystic Disease
1 . Multiple cysts are seen in atrophic, echogenic
kidneys. This is typical of acquired cystic disease
(ACD).
2. ACD predisposes patients to renal tumors.
3. Transplantation improves the natural history of
ACD.
4. Cysts are isolated in the kidneys. Other organs are
not involved.
Reference
Levine E, Slusher SL, Grantham ]], Wetzel LH: Natural
history of acquired renal cystic disease in dialysis
patients: A prospective longitudinal CT study. A]R
Am ] RoentgenoI 1 99 1 ; 1 56:50 1 - 506.
Cross-Reference
Ultrasound: THE REQUISITES, pp 87-88.
Comment
Acquired cystic disease (ACD) is a condition that is
commonly seen in patients with c1uonic renal failure. It
is especially prevalent in patients on dialysis and increases
with the duration of dialysis. After 3 years of
dialysis, the incidence is approximately 80%. The genesis
of the cysts is believed to be hyperplasia of the
tubular epithelium with resulting nephron dilatation.
The cause of the epithelial hyperplasia has not been
discovered. Successful treatment of the renal failure
with transplantation has been shown to reverse the
development of these cysts.
One of the complications of ACD is hemorrhage into
the cysts, the perinephric space, or the subcapsular
space. This hemorrhaging can cause Significant morbidity
and even mortality. The other potential complication
is the development of renal cell carcinoma. The incidence
of renal cancer is estimated at approximately 1 0%
in patients with ACD.
On sonography, the typical appearance is that of
small echogenic kidneys with multiple cortical-based
cysts. Early in the process, the cysts are small, and,
therefore, it may be difficult to demonstrate all of the
classic characteristics of simple cysts. With tinle, the
cysts become more numerous and larger. In fact, ACD
may result in overall enlargement of the kidneys to the
point where they can be confused with kidneys with
polycystic kidney disease.
Renal cell cancer can be recognized as a solid mass
contrasted to all of the adjacent cysts. Because the
differential diagnosis includes a hemorrhagic cyst, use
of color Doppler can be helpful if internal vascularity is
detected in a mass. Although contrast enhanced CT
and MRl are superior to sonography in detecting renal
cancers in patients with ACD, sonography remains a
valuable problem solving tool when CT or MRl is inconclusive.

Front 191

Measurement of flow vol u m e i n a patient fol lowi ng p lacement of a n
a rte riovenous fistu l a for hemodialysis.
1. What is the standard method of measuring blood flow volume using pulsed Doppler?
2. What does the line in the center of the waveform indicate?
3. What does TAM stand for?
4 . Does this method work best in large vessels with high flow or in small vessels with low flow?

Back 191

Measu rement of Flow Vo lume
l . Multiply the cross-sectional area of the vessel b y the
average flow velOCity.
2 . The line in the center of the waveform is the mean
flow velocity.
3 . TAM stands for Time Averaged Mean velocity.
4 . This method works best in large vessels with high
flow volumes.
Reference
Taylor K]W; Holland S: Doppler US: Part I. Basic principles,
instrumentation, and pitfalls. Radiology
1 990; 1 74: 297-307.
Comment
Flow volume measurements are possible with Doppler
techniques. They are calculated by multiplying the velocity
by the cross-sectional area of the vessel. In most
cases, the area of the vessel is obtained by measuring a
diameter and using the equation for area, assuming that
the vessel is circular in cross section. The velocity is
obtained from a standard angle-corrected pulsed Doppler
waveform. At any point in time, the waveform displays
a range of velocities from a maximum to a minimtilll.
In order to avoid overestimation of flow (by using
the maximum velocity) or underestin1ation of flow (by
using the mininmm velocity), one must multiply the
area of the vessel by the mean velocity. Internal software
is provided so that the mean velocity can be determined
at each point in time. It is also important to realize that
the flow velOCity in a vessel varies in different parts of
the lumen. Therefore, one must open up the Doppler
sample volume so that it includes the entire diameter of
the lumen.
If the flow is constant and nonpulsatile, then a single
mean velocity obtained at any point in time is adequate
to measure flow volume. If the flow is pulsatile, such as
the arterial flow in this case, then the mean velOCity has
to be averaged over time to obtain a time averaged
mean velocity (TAM). It is the TAM that is multiplied by
the cross-sectional area to calculate flow voltune .

Front 192

Transverse views of the g a l l bladder.
1 . Describe the abnormal findings.
2. Is this abnormality more common in men or in women?
3. Is this a medical or a surgical condition?
4. What other gallbladder abnormalities can sinmlate this condition?

Back 192

Emphysematous Cholecystitis
1 . The first image shows an echogenic reflection along
the nondependent wall of the gallbladder that casts
a dirty shadow. The second image shows ring-down
artifact arising from the same area. These findings
indicate air and are consistent with emphysematous
cholecystitis.
2. Emphysematous cholecystitis is more common in
men, presumably because they have a higher
incidence of vascular disease than women.
3. Tlus condition represents a severe form of
cholecystitis and should be treated surgically, or, if
the patient is not an operative candidate, with
percutaneous cholecystostomy.
4. Other causes of increased echogenicity in the
nondependent wall include porcelain gallbladder
and a gallbladder full of stones
Reference
MidcLleton WD: The gallbladder. In Goldberg BB (ed):
Diagnostic Ultrasound. Baltimore, Williams & Wilkins,
1 993, pp 1 1 6- 142.
Cross-Reference
Ultrasound: THE REQUISITES, pp 44-45.
Comment
Emphysematous cholecystitis represents a rare and advanced
form of complicated cholecystitis. It occurs in
elderly patients with underlying vascular disease. It is
believed that infection with gas-forming organisms results
from gallbladder ischemia. Therefore, many of
these patients have diabetes and many do not have
gallstones. The risk of perforation is significantly increased
in patients with emphysematous cholecystitis.
Therefore, surgery should be performed unless there
are contraindications to surgery. Percutaneous catheter
drainage is an alternative if the patient cannot tolerate
surgery.
The sonographic appearance of emphysematous cholecystitis
can overlap that of porcelain gallbladder and a
gallbladder completely filled with stones. All appear as
an echogeluc curvilinear reflector with posterior shadowing.
In most cases, the shadow is dirty with emphysematous
cholecystitis and clean with the other two conditions.
In addition, gas generally produces a brighter
reflection than calcification or stones. Finally, gas often
produces a ring-down artifact, and stones and calcification
do not. In this case, a ring-down artifact is seen on
the second image; thus, the diagnosis of emphysematous
cholecystitis can be made with confidence.

Front 193

Dual transverse and longitudinal views of the left and rig ht biceps
tendon groove.
1 . Describe the abnormality.
2. Is this diagnosis difficult to make clinically?
3. Which head of the biceps muscle is involved?
4. Are there other conditions that should be considered?

Back 193

B iceps Tendon Ru pture
1 . The transverse views show an empty biceps tendon
groove on the right. The longitudinal views show
lack of the normal fibrillar pattern in the tendon
groove.
2 . In most patients, the tendon and muscle belly
retract and produce a bulge in the anterior arm that
is easy to see and feel on physical examination.
3. The long head is involved.
4. In addition to tendon rupture, the differential
diagnosis for an empty biceps tendon groove
includes tendon dislocation and anisotropic effects
due to improper transducer angulation.
Reference
Middleton WD: Shoulder pain. In Bluth EI, Benson C,
Arger P, et al (eds): The Practice of Ultrasonography.
New York, Thieme, 1 999.
Cross-Reference
Ultrasound: THE REQUISITES, P 4 5 5 .
Comment
Patients with impingement syndrome of the shoulder
may have symptoms related to the rotator cuff, the
biceps tendon, or both. The origin of these symptoms
can be difficult to sort out cliIucally. For this reason, it
is important to scan the biceps in patients suspected of
having a rotator cuff tear.
Rupture of the biceps tendon is usually readily detected
on physical examination because the retracted
muscle belly forms a lump in the upper arm that becomes
more pronlinent when the biceps is flexed. On
sonography, biceps tendon rupture is one of the causes
of an empty-appearing groove. Biceps tendon dislocation
is the other cause. One must also be aware that if
the transducer is not oriented perpendicular to the
tendon, the atusotropic properties of the tendon cause
it to appear hypoechoic, and the result is an emptyappearing
groove.
In some cases, a ruptured biceps tendon becomes
scarred to the tendon groove or just below the tendon
groove. Tlus is referred to as autotenodesis, and in such
cases there is minimal or no retraction of the muscle
belly, and the diagnosis is less apparent on physical
examination. Sonographically, the tendon appears attenuated
at the level of the groove, but there are usually
some detectable fibers, especially on longitudinal views.
In most cases, the diagnosis is still possible because the
intra-articular portion of the biceps is absent.

Front 194

Long itu d i n a l view of the superficial femoral artery and the
common carotid a rtery. (See color plates.)
1 . Assuming that at any point in time, there is a sinlilar blood flow velocity and direction along the
length of these vessels, why is the color assignment different in the proximal and distal segments?
2. Can the peak systolic flow velocity be determined from these images?
3. Other than blood flow velocity, what determines the color shading?

Back 194

Effect of Frame Rate on Color
Doppler Im ages
1 . Each image takes a certain amount of time to
create. If the frame rate is 1 0 frames/sec, each
image takes one tenth of a second to make. The
first image, of the superficial femoral artery, was
created between the time of antegrade systolic flow,
producing the red segment, and retrograde early
diastolic flow, producing the blue segment. The
second image, of the common carotid artery, was
created between end-diastole and early systole, so
that the darker red segment of the vessel reflects
slower diastolic flow, and the lighter red segment
reflects faster systolic flow.
2 . Color Doppler i1nages are encoded based on mean
velocity. A pulsed Doppler waveform is required to
measure peak velOCity.
3. Color shadillg is determined by the mean frequency
shift. In addition to velOCity, mean frequency shift is
dependent on the Doppler angLe, the transmitted
frequency, and the amount of filtering of lowfrequency
shifts.
Reference
Middleton WD: Color DoppLer image optilnization and
i1lterpretation. Ultmsound Q 1 998; 1 4 : 1 94-208.
Comment
In analyzing color assignments, it is i1nportant to remember
that it takes a finite amount of time to generate
each frame of a real-time scan. If the flow velocity or
the flow direction in a vessel varies with time, different
segments of the vessel may have different color assignments
because they were generated at a different POillt
in tilne. This is seen frequently ill arteries where there
is a rapid change in flow velocities between diastole
and peak systole.
Another i1nportant point to recognize is that at any
point in time, there is a range of frequency shifts withill
any pixel in the image. This occurs because red blood
cells are moving at different velocities and in slightly
different directions. If one looks at a Doppler waveform,
at any point in time it is possible to determine a maximum,
a minimum, and a mean frequency shift. The
color that is assigned to a pixel during color Doppler
scanning depends on the mean frequency shift. In many
clinicaL applications (such as estilnatillg carotid stenoses),
it is i1nportant to measure the maximu m frequency
shift. This is not possible using conventional
color Doppler and can onLy be done with puLsed DoppLer
waveform analysis.

Front 195

G rey-scale and color Doppler views of the po rta hepatis. (See color
plates.)
1 . What is the cause of the multiple channels seen in the porta hepatis?
2. Is the blood flow in these vessels toward the liver or away from the liver'
3. Are these vessels arterial or venous?
4. Do they form anterior or posterior to the portal vein and hepatic artery?

Back 195

Cavernous Tra nsformation
of the Portal Vein
1 . The channels seen in the porta hepatis represent
collateral vessels that have developed because of
portal vein thrombosis.
2. Overall flow ill these collaterals is toward the liver
(hepatopetal) .
3. These vessels represent venous collaterals.
4. Portal collaterals typically form anterior to the
portaL veill and hepatic artery.
Reference
Weltin G, Taylor K.rw, Carter AR, Taylor CR: Duplex
Doppler: Identification of cavernous transformation
of the portal vein. AJR Am J Roentgenol 1 985 ;
1 44 :999- 1 00 l .
Cross-Reference
Ultrasound: THE REQUISITES, pp 26-27.
Comment
In the setting of portal vein thrombosis, periportal collaterals
often form and supply venous flow to the liver.
If these collaterals are large enough, they can be seen
on grey-scale and on color or power Doppler images of
the porta hepatis. They appear as multiple tortuous
vessels. Although it is unusual, it is possible to see
periportal collaterals when the portal veill is compromised
but not completely thrombosed.
In most cases, the tlu'ombosed portal vern is also seen
in the setting of cavernous transformation. However, if
the thrombosed portal vein is thill and fibrosed, or if it
is filled with thrombus that is isoechoic to the adjacent
liver, it may be hard to identify and/or recognize. If lie
portal veill thrombus is not appreciated, and there is a
single periportal collateral, tlus collateral may be nlistaken
for a patent maill portal veill. One way to avoid
this nUs take is to look at the relationslup of the vessel
to the hepatic artery. The normal portal vern travels
deep to the hepatic artery. Periportal collaterals travel
anterior to the hepatic artery. Another potential pitfall
in the proper interpretation of cavernous transformation
is an enlarged, tortuous hepatic artery. Arterial enlargement
usually occurs in the setting of cirrhosis and portal
hypertension and can be distillguished from venous
collaterals by Doppler waveform analysis. In the majority
of cases, the collaterals form ill the hepatoduodenal
ligament. Recently, cases have been observed where the
collaterals form in the wall of the common bile duct,
producillg marked duct wall thickening.

Front 196

Transverse views of the pancreas a n d of the celiac axis. (See color
plates.)
1 . Describe the abnormalities .
2 . Should this patient see a surgeon?
3. What other sites should be evaluated sonographically while the patient is being scanned?
4. What is the best way to establish the diagnosis?

Back 196

Vascular I nvasion from Pancreatic Cancer
1 . The first image shows a hypoechoic mass a t the
junction of the pancreatic body and tail. The
second unage shows a concentric soft tissue mass
surrounding the celiac axis. These findings are
consistent with pancreatic cancer that has encased
the celiac axis.
2. Because of the vascular involvement, this patient is
not a surgical candidate.
3. Other sites of metastases that would make the
patient unresectable include the liver and the
peritoneum.
4. Biopsy can be performed with endoscopic
ultrasound guidance, percutaneous ultrasound
guidance, or CT guidance.
Reference
E Angeli, M Venturini, A Vanzulli: Color Doppler imaging
in the assessment of vascular involvement by pancreatic
carcinoma. A]R A m ] Roentgenol 1 997 ; 1 68 : 1 93 -
1 97
Cross-Reference
Ultrasound: THE REQUISITES, pp 1 35 - 1 36.
Comment
Patients with ductal adenocarcinoma of the pancreas
frequently present with jaundice or with nonspecific
abdominal pain. Because of their presentation, many of
these patients are first imaged with ultrasound. Once
the tumor is detected, the next aspect of the patient's
evaluation is to determine the resectability of the tumor.
Common factors that render a tumor nonresectable include
liver metastases, invasion of the peripancreatic
vessels, and spread to the peritoneum. Sonography is
capable of detecting all of these modes of metastases.
The vessels that are most frequently invaded include
the superior mesenteric artery, the celiac axis and its
branches, and the portal, splenic, and superior mesenteric
veins. Normally the peripancreatic arteries are surrounded
circumferentially by dense, echogenic, fibrofatty
tissue. Invasion of the arteries is indicated when
this echogenic tissue is interrupted by hypoechoic soft
tissue. Complete encasement of the artery by soft tissue
is essentially diagnostic of invasion and makes the patiellt
nonresectable. Encasement of less than 360 degrees
is less reliable but nevertheless significantly reduces
the chance of resection with clear surgical
margins. Venous invasion is more difficult to detect
because the veins are normally in direct contact with
the pancreas without intervening fat. Thrombosis and
narrowing of the peripancreatic veins are signs of venous
invasion. Development of peripancreatic venous
collaterals is a secondary sign of venous obstruction.

Front 197

Long itu d i n a l views of the kid n ey i n slig htly d ifferent obliquities.
1 . What is the differential diagnosis of nonshadowing soft tissue masses in the renal calyces?
2. What is the most likely diagnosis in this case?
3. Does this finding require further evaluation?
4. How often is this finding seen in the absence of hydronephrosis?

Back 197

Promi nent Papillary Tips
1 . Blood clots, sloughed papillae, fungus balls ,
transitional cell cancer, malakoplakia, leukoplakia,
cholesteatoma, and prominent papillary tips can
potentially cause nonshadowing calyceal defects.
2. The fact that the lesions are seen in multiple
calyces and appear similar in all is very typical of
prominent papillary tips.
3. This appearance is so characteristic of prominent
papillary tips that no further evaluation is needed.
4. The papillary tips appear prominent because the
calyx is slightly distended by the hydronephrosis.
This finding is almost never seen in the absence of
hydronephrosis.
Reference
Dillard JP, Talner LB, Pinckney L: Normal renal papillae
simulating calyceal filling defects on sonography. A]R
A m ] Roentgenol 1 987 ; 1 48:895 -896.
Cross-Reference
Ultrasound: THE REQUISITES, pp 94-96.
Comment
The normal renal pyramids are cone-shaped, with the
apex of the cone directed toward the calyx. The
rounded apex, or papillary tip, protrudes into the calyx,
producing the typical cuplike appearance seen on intravenous
m"ograms. In the normal situation, the angles of
the calyceal fornices are acute, and there is not enough
urine in the calyces to make the outline of the papillary
tip visible. However, in the setting of hydronephrosis,
the calyx may distend with urine, and the papillary tip
can become surrounded by the urine in the calyceal
fornices. When viewed Ul long axis, the morphology of
the papillary tip is usually easily visible, and its origin is
recognizable. When viewed in short axis, the papillary
tip can simulate a pathologic filling defect in the collecting
system. This pitfall is very unusual in native kidneys
and slightly more common in renal transplants.
Characteristic features include the similar appearance
seen in several calyces and the presence of mild to
moderate hydronephrosis. Obtaining views in various
obliquities can help in distinguishing this pitfall from
true filling defects, but simple awareness of this pitfall
is usually enough to avoid misinterpretation.

Front 198

Transverse view of the l iver.
1 . What artifact is demonstrated on this image?
2. What causes this appearance?
3. Is this finding seen in the absence of ascites?

Back 198

Diaphragmatic Duplication Artifact
1. Both images show artifactual duplication of the
diaphragm.
2. This artifact is caused by refraction of sound
between the edge of the liver and the ascites.
3. In the absence of ascites there would be soft tissue
around the liver, and refraction would not occur, so
this artifact would not be seen.
Reference
Middleton WD, Melson GL: Diaplu'agmatic discontinuity
associated with perihepatic ascites: A so nographk
refractive artifact. AIR Am I Roentgenol 1988;
151 :709-71 1.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 112-115.
Comment
The subject of sound refrac tion in the abdominal midline
has been covered in a previous case (case 179).
This case is an example where sound is refr acted at the
oblique interfa ce between a solid structure (the liver),
in which sound travels more rapidly, and a liquid (ascites),
in which sound travels more slowly. Interfa ces such
as tlus act as an acoustic lens and cause sound waves
to bend. According to Snell's law, the angle of incidence
in the first tissue divided by the speed of sound in the
first tissue equals the angle of transmission in the second
tissue divided by the speed of sound in the second
tissue.
When an ultrasound pulse is transmitted, the computer
assumes that it travels in a straight line and that
all reflections arise from that line. When the sound
wave is bent, the reflections no longer arise fro m the
original line of transmission, so the computer misplaces
all of those echoes along the line that it assumes the
sOlmd is traveling. Therefore , the net result of refraction
is mislocalization of structures. In fa ct, structures become
duplicated because they are insonated once by a
sound wave that is not bent and a second time by a
sound wave that has been bent. Therefore the computer
thinks the echoes are ariSing from two diffe rent locations.
Refraction causes duplication artifacts where the duplicated
structures are located side by side at the same
depth in the image. The other common duplication
artifact is caused by mirror image s, and in that case, the
duplication artifact is always deeper in the image than
the original structure.

Front 199

Long itud inal extended field of view of the left calf and dual longitudinal
images of the left and right g astrocnemius and soleus m u scles.
1. Which leg is abnormal?
2. What is the most likely diagnosis?
3. Which muscle is usually affected?
4. What conditions is this abnormality frequently confused with clinically?

Back 199

Muscle Te ar and Hemato ma
1. Abnormal separation of the gastrocnemius and
soleus muscles is observed on the left side. The
right side is normal.
2. The findings are typical of a tear of the
gastrocnemius muscle at its attaclunent to the
aponeurosis with the soleus.
3. This finding is sometimes referred to as tennis leg
and occurs at the distal aspect of the medial head
of the gastrocnemius.
4. Patients with tlus condition frequently are referred
fo r imaging to rule out deep vein thrombosis or
ruptured Baker's cyst.
Reference
Bianchi S, Martinoli C, Abdelwahab IF, et al: Sonographic
evaluation of tears of the gastrocnemius medial head
(" tennis leg"). I Ultrasound Med 1998; 17: 157 -162.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 112-115 .
Comment
Te ars of the medial head of the gastrocnemius muscle
are a common problem in middl e-aged amateur athletes
who are physically active. Tlus tear is sometimes referred
to as tennis leg. It occurs when the knee is
extended (producing stretclung of the gastrocnemius)
and the cali' muscles are fo rcefully contracted. Tlus injury
generally results in acute pain and swelling of the
calf. Te nderness is usually localized to the medial aspect
of the mid calf. Although the Ius tory and clinical findings
are usually characteristic, other abnormalities are
often considered. Imaging is therefore used to establish
a definitive diagnosis and to determine the extent of
the injury.
The normal gastrocnemius muscle inserts into an
aponeurosis located between the gastrocnenuus and the
soleus. Normally, tl1e fibers of the gastrocnemius can be
visualized extending directly to tlus aponeurosis. A tear
is diagnosed by identifying a hematoma between the
muscle fibers and the aponeurosis. If this injury is imaged
acutely, the hematoma may appear hyperechoic.
However, with time, the clotted blood starts to lyse, and
the hematoma develops areas of liquefaction. Ultimately,
the hematoma converts into a simple-appearing fluid
collection. Tius evolution takes several days to weeks
to occur.
Once the correct diagnosis is established, these patients
are usually managed conservatively with various
degrees and durations of rest and immobilization.

Front 200

Pu lsed Doppler waveform from the i ntrahepatic portion of the right
hepatic artery and the left h epatic a rtery i n a liver transplant patient.
(See color plates.)
1 . What do both of these waveforms have in common?
2. What else is abnormal about the left hepatic artery?
3. What test would you recommend next?
4. What would you expect to see on a cholangiogram?

Back 200

Hepati c Artery Thrombosis Status Post
Liver Tra nsplant
1. Both arteries demonstrate a blunted (parvus-tardus)
pattern with decreased resistive indices.
2. Flow in the left hepatic artery is reversed,
indicating that it is serving as a collateral.
3. The next test should be an arteriogram. This test
was performed and confirmed complete hepatic
artery thrombosis with reconstitution of the left
hepatic artery via the left gastric artery.
4. Since the bile ducts in a liver transplant are
dependent on hepatic arterial supply, arterial
thrombosis causes biliary ischemia and can produce
strictures or complete necrosis of the ducts.
Reference
Wa chsberg RH: Sonography of liver transplants. Ultrasound
Q 1998; 1 4(2):76-94.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 30-3 1.
Comment
Hepatic artery stenosis or thrombosis is the most common
vascular complication fo llowing liver transplantation.
It occurs in approximately 10% of cases. Significant
hepatic artery stenosis and hepatic artery thrombosis
with collateral flow can be detected with Doppler scanni.ng
by noting a blunted arterial waveform distal to the
stenosis. Blunting can be quantitated in several ways.
The easiest is by measuring the resistive index. If the
resistive index is less than 0.4, the waveform should be
considered severely blunted, and a diagnosis of hepatic
artery stenosis or thrombosis should be made. If the
resistive index is between 0.4 and 0. 5, then hepatic
artery stenosis/thrombosis should be considered. If the
resistive index is above 0.5, hepatic artery stenosis/
thrombosis is very unlikely. Stenosis, thrombosis, or
severely diminished flow may also cause an inability to
detect flow. Realize, however, that lack of detectable
flow may also be due to teclmical fa ctors. Therefore, if
the scan is diffi cult or limited in some way, inability to
confirm arterial flow should be correlated carefully with
clini.cal parameters. If the examination is not limited
and no flow is detectable, then arterial compromise
should be suggested.

Front 201

Longitudinal g rey-scale view a nd power Doppler scan
of the carotid bifurcation. (See color plates.)
1 . Describe the abnormalities .
2 . How good i s ultrasound a t making this diagnosis?
3. What is the Significance of this finding?
4. How does intraplaque hemorrhage appear?

Back 201

Ulcerated Carotid Plaque
1. The grey-scale view shows a hypoechoic plaque at
the origin of the internal carotid artery. The power
Doppler scan shows an area of blood flow
extending into the mid aspect of the plaque. These
findings are typical of plaque ulceration.
2. Ultrasound is not very sensitive at detecting plaque
ulceration.
3. Ulceration indicates a higher risk of emboli
regardless of the degree of stenosis.
4. Intraplaque hemorrhage appears as a fo cal
hypoechoic area in the plaque or as areas of
heterogeneity.
Reference
Bluth EI: Evaluation and characterization of carotid
plaque. Semin US CT MRI 1997; 18:57-65 .
Cross-Reference
Ultmsound: THE REQ UISITES, pp 476-477.
Comment
Some plaques that produce minimal stenosis can still
produce clinical symptoms by serving as a source of
emboli. This occurs when the intimal surface of the
plaque breaks down and exposes the plaque to intraluminal
blood. One of the first stages in tills process is
the development of intraplaque hemorrhage . Detection
of intraplaque hemorrhage on sonography is controversial.
Some believe that son ographic resolution is generally
not sufficient to identify intraplaque hemorrhage.
Others believe that intraplaque hemorrhage is reliably
seen as fo cal areas of decreased echogenicity, while
stable plaques (i.e., plaques that do not break down and
produce emboli) appear homogeneous.
Plaque ulceration also appears as a focal area of
decreased echogenicity. On color or power Doppler,
ulceration appears as a defect in the plaque that communicates
with the lumen and has detectable internal flow.
With large ulcers, a swirling pattern of flow is seen.
Although some ulcers are certainly detectable with
color Doppler, many ulcers are not . In fa ct, many ulcers
that are fo und pathologically are not even detectable
with arteriography. Partially because of the limitations
in detecting ulceration and in characterizing plaque, the
major fo cus of carotid Doppler scanning is to identify
and estimate the severity of stenoses.

Front 202

Pregnant patient with a left u reteral stone (the same patient shown i n
case 27). T h e figures include a longitudinal view of the left kid n ey,
transverse color Doppler view of the bladder, and pu lsed Doppler
waveforms from the left and rig ht kidney.
1 . What is a normal resistive index (R1) for an intrarenal artery?
2. Are RI measurements a reliable means of determining the presence or absence of urinary obstruction?
3. What is being shown on the color Doppler view of the bladder?
4. In the setting of acute high-grade urinary obstruction, which becomes abnormal first, RI
measurements or ureteral jets?

Back 202

U rinary Obstruction
1 . A normal resistive index (RI) ranges from 0.5 to 0.7.
2. TItis is a controversial topic, but RI measurements
seem to have significant linlitations in the
evaluation of urinary obstruction.
3. The color Doppler view shows a ureteral jet arising
from the left ureteral orifice.
4. Ureteral jets become abnormal before the RI
becomes abnormal.
References
Baker S, Middleton WD: In vivo color Doppler sonographic
analysis of ureteral jets in normal voltmteers:
Importance of the relative specific gravity of urine
in the ureter and bladder. AJR Am J Roentgenol
1 992 ; 1 59:773-77 5 .
Burge JR, Middleton WD, McClennan B L , Rildeboldt CF:
Ureteral jets in healthy subjects and in patients with
unilateral ureteral calculi: Comparison with color
Doppler ultrasound. Radiology 1 99 1 ; 1 80:437-442.
Koelliker SL, Cronan JJ: Acute urinary tract obstruction:
imaging update. Urol CUn North Am 1 997;24:57 1 -
582 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 77-8 1 .
COlll1llent
On sonography, the detection of urinary obstruction
depends primarily on the identification of hydroneplu'osis.
Unfortunately, urinary tract obstruction is not synonymous
with hydronephrosis. For this reason, a fair
amow1t of effort has been directed toward developing
ways that can help sort out kidneys that are obstructed
but not hydronephrotic and kidneys that are hydronephrotic
but not obstructed.
One relatively direct way of looking at this is to
monitor the flow of urine out of the ureters and into
the bladder. This can be done in a qualitative manner
by watching for ureteral jets. For many years, it was
known that grey-scale ultrasound was capable of identifying
echogenic jets of urine periodically entering the
bladder from the ureteral orifices. However, detection
of ureteral jets on grey-scale imaging is intermittent and
often subtle, and ureteral jets were never used to analyze
urinary obstruction. When color Doppler became
available, ureteral jets became much easier to recognize,
and it became possible to obtain useful information
from the analysis of ureteral jets. In particular, studies
showed that ureteral jets were elintinated by moderate
and high-grade obstruction, and a useful characteristic
of ureteral jets is that they disappear immediately in the
setting of obstruction and reappear immediately when
2 1 8
the obstruction is relieved. One limitation is that lowgrade,
partial obstructions may not cause a detectable
change in ureteral jets.
In order for ureteral jets to be analyzed, they must
be detectable. For tIus reason, it is important to realize
that ureteral jets are detected only when there is a
difference in the density between the urine in the bladder
and the urine in the ureters. This is usually the case
because density of urine in the bladder is an average of
the density of urine that has accumulated over time and
thus is slightly different from the density of urine exiting
the ureter at any particular point in time. However,
when someone is well hydrated and empties Ius or her
bladder inunediately prior to the examination, there will
be dilute urine in both the bladder and the ureters, and
jets may not be seen even when there is very active
diuresis. Therefore, patients should be instructed to
avoid completely emptying the bladder prior to the
analysis of ureteral jets.
Doppler analysis of renal blood flow is another means
of studying renal dysfunction. Tlus is generally done by
measuring the RI of intrarenal arterial waveforms. Many
different underlying renal diseases will affect the RI
value. Urinary obstruction is no exception. Tlus is likely
due to the release of vasoactive substances that cause
vasoconstriction. Since diastolic flow is affected to a
greater extent than systolic flow, the effect can be identified
by noting an increase in the RI measurement. Studies
have shown that the best value to use as the upper
limit of normal for the RI is 0.70. In the cfuucal setting
of suspected unilateral obstruction, an RI value greater
than 0.70 on the affected side should raise the suspicion
of obstruction even if there is no grey-scale evidence of
hydronephrosis. If there is underlying renal parenchymal
disease that causes bilateral elevation of the RI then
RI asynunetry of greater than 0.08 to 0. 1 0 SilOUld
prompt increased consideration of unilateral obstruction.
While a unilateral elevation in the RI can be helpful,
it is important to realize that the RI may remain elevated
for a variable length of time after obstruction has been
relieved. A normal RI is not very useful and should not
be used as a way of excluding obstruction. Part of the
problem is that in the setting of acute obstruction it
tal(es time for the RI to become abnormal. In additi

Front 203

G rey-scale views and accom panying pu lsed Doppler waveforms from the
hepatic vei n and the portal vei n .
1 . What i s wrong with the hepatic venous waveform?
2. What does this indicate?
3. What is wrong with the portal venous waveform?
4. What does this indicate?

Back 203

Passive Hepatic Congestion
1. The hepatic vein waveform shows inversion of the
normally antegrade systolic pulse so that there is
only one antegrade pulse, which occurs during
diastole.
2 . Inversion of the systolic peak indicates the
presence of tricuspid regurgitation.
3. The portal vein waveform is abnormally pulsatile.
4. Portal vein pulsatility to this degree indicates
passive congestion.
References
Abu-Yousef MM: Duplex Doppler sonography of the
hepatic vein in tricuspid regurgitation. AJR Am J
RoentgenoI 1991;156:79-83.
Duerinckx A, Grant E, Perrella R, et al: The pulsatile
portal vein: Correlation of duplex Doppler with right
atrial pressures. Radio logy 1990; 176:655-658.
Gallix BP, Taourel P, Dauzat M, et al: Flow pulsatility
in the portal venous system: A study of Doppler
sonography in healthy adults. AJR Am ] Roentgenol
1997; 169: 141- 144.
Cross-Reference
Ultrasound: THE REQUISITES, pp 29-30.
Com.ment
The appearance of the normal hepatic vein waveform
has been described in a previous case (case 112) . Recall
that there should be ante grade flow out of the liver at
all times except fo r during right atrial contraction. In
fa ct, the antegrade flow is divided into a systolic component,
which is usually larger, and a diastolic component,
which is usually smaller. In this case, there is only one
antegrade component. During most of the cardiac cycle
there is retrograde flow in the hepatic veins. This means
the effective venous outflow fr om the liver is reduced.
Consequently, the hepatic sinusoids become congested.
In the normal liver, the portal venous system is isolated
from the right atrial pulsations by the hepatic
parenchyma. Therefore , the portal venous waveform is
normally flat witl1 minimal pulsatil ity. However, when
the sinusoids become congested, the right atrial pulsations
can be transmitted to the portal vein, and the
portal vein waveform becomes pulsatile. It is important
to realize that some degree of portal vein pulsatility can
be normal. This is especially true in otherwise healthy
thin patients. The point at which a pulsatile portal
vein should be called abnormal is not precisely defined.
However, if the maximum velocity drops below zero,
then the possibility of right-Side heart dysfunction
should be considered.

Front 204

Views of the pancreas in two patients.
1 . Describe the abnormality seen in these patients.
2. Is this lesion most likely benign or malignant?
3. What type of fluid would you expect to aspirate?
4. Is this patient more likely to be 20 or 60 years old?

Back 204

Microcystic Serous Cystadenoma
of the Pancreas
1. Both unages show a mass that is predomffiantly
solid-appearing but that contains multiple tiny
cystic spaces. This is a typical appearance of
microcystic (serous) cystadenomas.
2. These are benign lesions with no malignant
potential.
3. The cyst fluid is glycogen-rich serous fluid.
4. This lesion is typically seen in elderly women.
Reference
Buck JL, Hayes WS: Microcystic adenoma of the pancreas.
Radiographies 1990; 10:313-322.
Cross-Reference
Ultrasound: THE REQ UISITES, pp 137- 139.
Com.ment
Microcystic serous neoplasms of the pancreas are benign
lesions that consist of multiple small cystic spaces.
The individual cysts typically range fr om less than 1 I11111
to 20 mm U1 diameter. On cut section, they have a
honeycomb or spongy appearance. The cyst fluid, and
particularly the cellular cytoplasm, is rich ill glycogen.
These cysts may contain a central stellate scar, and
central calcification occurs U1 up to 40% of lesions.
There is no significant predilection to any part of the
pancreas. It is uncommon fo r these tumors to produce
symptoms or to cause obstruction of the bile duct or
pancreatic duct unless they are very large. Together
with mucu10uS cystic neoplasms, they account fo r approximately
10% of pancreatic cysts.
On sonography, tl1e lesion usually appears solid with
some small cystic areas. Depending on the size of the
internal cystic spaces and the number of reflecting u1terfa
ces between the cysts, the lesion may range ill echogenicity
from hyperechoic to hypoechoic. In some
cases, the appearance is of a cystic mass composed of
multiple small cysts. The central scar is rarely seen on
sonography. It is not uncommon fo r the lesion to appear
very cystiC on CT and very solid on ultrasound. This
combu1ation should suggest the diagnosis of microcystic
serous cystadenoma. These tumors are typically very
vascular, and this is occasionally reflected on color
Doppler scans

Front 205

Color Doppler view of hepatic vein b ranches and pulsed Doppler
waveform from one of these veins. (See color pl ates.)
1 . How sensitive is sonography in establishing the diagnosis of the condition shown in this case?
2. What happens to portal venous flow in the condition shown here?
3. Is normal hepatic venous flow hepatofugal or hepatopetal?
4. What causes flattening of the hepatic venous waveform?

Back 205

Hepatic Vei n Thrombosis
1 . Sonography is a relatively sensitive way to diagnose
hepatic vein tlu-ombosis, and it is a reasonable way
to start the imaging evaluation. However, there are
cases where the hepatic veins cannot be seen well
on ultrasound (e.g., end stage cirrhotic livers and
extremely enlarged livers), and alternative
modalities such as MRI may be reqlUred.
2. Hepatic vein thrombosis is one of the posthepatic
causes of portal hypertension. Therefore, all of the
signs of portal hypertension can occur.
3. Normal hepatic venous flow is hepatofugal (away
from the liver). In this case, the flow in one of the
branches is hepatopetal (toward the liver).
4. Anything that isolates the hepatic vein from the
right atrium can cause flattening of the normal
venous pulsatility. Possibilities include hepatic vein
thrombosis, inferior vena cava or hepatic vein
webs, extrinsic compression, and tumor invasion.
Cirrhosis can also cause flattening of the normal
venous pulsatility because regenerating nodules
compress the hepatic veins and cause strictures.
Reference
Kane R, Eustace S: Diagnosis of Budd-Chiari syndrome:
Comparison between sonography and MR angiography.
Radiology 1 995 ; 1 95 : 1 1 7- 1 2 1 .
Cross-Reference
Ultrasound: THE REQUISITES, pp 27-29.
Corrnnent
Hepatic vein thrombosis (HVT) can be either bland or
due to tumor thrombus. Bland thrombus appears like
thrombus elsewhere in the body. It can range from
hyperechoic to anechoic. In the acute setting, extensive
hepatic vein thrombosis can manifest as a Budd-Chiari
syndrome with hepatic failme, liver enlargement, and
massive ascites. In such cases, visualization of the hepatic
veins may be very difficult. In chronic cases, the
hepatic veins may be small and fibrotic and difficult to
see. Therefore, it is important to look for the hemodynamic
consequences of HVT in addition to looking for
the thrombosis itself.
Because HVT isolates the hepatic vein from the right
atrium, the pressme fluctuations in the right atrium do
not get transferred to the patent portions of the hepatic
vein. Therefore, the hepatic vein waveform loses its
pulsatility and becomes monophasic . Since hepatic venous
flow from obstructed segments calUl0t flow to the
inferior vena cava in the normal way, it seeks collateral
pathways, usually via unobstructed hepatic veins (such
as accessory hepatic veins) or via subcapsular veins. In
both cases, there are segments of hepatic veins where
the flow is reversed as it travels toward the collateral.
222
This produces the typical appearance shown in this
case where one hepatic vein branch is flowing in a
hepatofugal direction and a communicating vein is
flowing in a hepatopetal direction .

Front 206

Magnified tra nsverse color Doppler view and pu lsed Doppler waveform
of the right renal a rte ry. (See color p l ates.)
1. What is the abnormality?
2 . Is this the most common site for renal artery stenosis?
3. Is this patient most likely male or female?
4. What is the treatment of choice for this condition?

Back 206

Fi bromuscular Dysplasia
1 . The color Doppler image shows very disordered
flow localized to the mid right renal artery. The
Doppler waveform shows increased velocity, with
the arterial signal aliased from the negative side of
the base line to the positive side of the base line.
2. TIus is not a common site for stenosis. Usually the
narrowing is closer to the origin of the renal artery.
3 . Renal artery fibromuscular dysplasia is more
common in women.
4. Angioplasty is the treatment of choice.
Reference
Luscher TF, Lie ]T, Stanson AW, et al: Arterial fibromuscular
dysplasia. Mayo CUn Proc 1 987;62:93 1 -9 5 2 .
Cross-Reference
Genitourinary Radiology: THE REQUISITES, P 395 .
Corrnnent
Fibromuscular dysplasia can affect the intima, media, or
adventitia of the artery. Medial fibroplasia is the most
common type in adults. After atherosclerosis, fibromuscular
dysplasia is the most common cause of renovascular
hypertension. It occurs most often in middle-aged
women. Unlike atherosclerosis, fibromuscular dysplasia
affects the mid and distal renal artery and spares the
proximal segment. It may extend into the branch vessels.
The classic "string of beads" appearance seen angiograplucally
is produced by fibromuscular ridges alternating
with areas of arterial wall thinning and aneurysm
formation. Percutaneous angioplasty is very effective in
restoring the patient's normal blood pressure.
The morphologic changes in the artery are almost
never visible sonographically. However, as in this case,
the disturbed flow can be detected as marked heterogeneity
in color assiglUnent on color Doppler scatu1ing.
This case is unusual because the patient was quite thin
and could be scanned with a linear array transducer,
allowing for resolution not typically seen. Because of
the location of the lesion, renal artery fibromuscular
dysplasia is more difficult to detect with Doppler scanning
than is atherosclerosis. When dealing with hypertensive
middle-aged or young adult women without a
history of vascular disease, it is very inlportant to visualize
the mid renal artery.

Front 207

Lo ngitudinal and two transverse g rey-sca le views and transverse power
Doppler view of the kid ney in a patient with flank pain.
1 . Describe the abnormalities.
2. How good is ultrasound at malting this diagnosis?
3. What is the role of ultrasound in managing these patients?

Back 207

Pyelonephritis
1 . The kidney is enlarged (16 cm), there is thickening
of the renal pelvis, there is a patchy area of
increased cortical echogenicity, and there is a focal
area of decreased vascularity seen on power
Doppler. These findings are typical of
pyelonephritis.
2. Many patients with pyelonephritis have
sonographically normal kidneys. Ultrasound is not a
good way of making the diagnosis.
3 . Since ultrasound is not sensitive at diagnosing
pyeloneplu-itis, its role is more to look for
complications in patients who are not responding
to treatment.
Reference
Baumgarten DA, Baumgartner BR: Imaging and radiologic
management of upper urinary tract infections.
Ural Clin North Am 1 997;24:545-569.
Cross-Reference
Ultrasound: THE REQUISITES, pp 99- 1 00.
Comment
Pyelonephritis usually arises as a result of the ascent of
infection from the bladder, or less commonly from a
hematogenous route. In adults, pyelonephritis is usually
diagnosed clinically, patients are treated with antibiotics,
and symptoms improve within 48 to 72 hours. In
this group of patients, radiologic imaging is not necessary.
However, patients with pyelonephritis may be imaged
for other reasons, or may be imaged prior to the
proper clinical diagnosis. Therefore, the appearance of
pyelonephritis should be recognized when it is encountered.
On sonography, the most common finding is usually
mild urothelial thickening of the renal pelvis, the ureter,
or the intrarenal collecting system. This is usually a
subtle finding and typically is not seen unless a directed
search is made. Normally the wall of the collecting
system is visualized as a single bright line that represents
the reflection between the surface of the wall and the
adjacent urine in the lumen. When the wall becomes
thick, the substance of the wall can be seen as a hypoechoic
layer adjacent to the normal surface reflection.
This produces a layered appearance with a bright central
layer and a hypoechoic peripheral layer. In this
respect, thickened urothelium appears similar to thickened
bile duct walls (case 1 56). In addition to infection,
stones in the ureter or renal pelvis can cause wall
thickening, as can indwelling stents. Urothelial thickening
may also appear after bouts of obstruction due to
redundancy of the wall. In kidney transplants, rejection
and ischemia are additional causes.
224
Other findings seen with pyelonephritis include renal
enlargement, patchy areas of either increased or decreased
echogenicity (often in a somewhat wedge
shape), loss of central sinus echogenicity, loss of corticomedullary
distinction, and tiny amm.mts of perinephric
fluid usually seen best around the poles of the
kidney. Color Doppler may show areas of decreased
perfusion that correspond to areas of decreased enhancement
on CT scans. All of these findings are more
difficult to see in adults than in children.

Front 208

Views of the kid ney i n two patients.
1 . Describe the renal masses shown on these llnages.
2. What is the differential diagnosis?
3 . What would the most likely diagnosis be if these patients also had pheochromocytomas?
4. What else can be done sonographically to assist in this differential diagnosis?

Back 208

Complex Renal Cysts
1 . Both masses are predominantly cystic but contain
significant solid-appearing internal components.
2. The primary possibilities include hemorrhagic cysts
and cystic renal cell cancer. Complex cystic masses
can also be due to infected cysts or abscesses,
multilocular cystic neplu"oma, partially tlu"ombosed
aneurysms, echinococcal cysts, or urinomas.
3. The presence of complex renal masses and
pheochromocytomas suggests von Hippel-Lindau
disease and renal cell cancer.
4. Color Doppler scanning would indicate a cystic
renal cell cancer if vascularity were seen in the
solid components. This was the case in the first
image. If the solid component were mobile when
the patient changed position, then the diagnosis
would be a hemorrhagic cyst with mobile clot. This
was the case with the second image.
Reference
Kawashima A, Goldman SM, Sandler CM: The indeterminate
renal mass. Radiol Clin Nortb Am 1 996; 34:997-
1 0 1 5 .
Cross-Reference
mtmsound: THE REQUISITES, pp 8 1 -84.
Comment
Benign renal cysts are the most common incidental
lesion detected during abdominal sonography. When
cysts have an anechoic lumen, a well-defined back wall,
and produce posterior acoustic enhancement, they require
no further evaluation. A limited number of thin
septations also require no further evaluation. However,
when they have a thick or irregular wall, thick septations,
or obvious solid elements similar to those seen
in these itnages, cysts should not be considered simple,
and further evaluation is necessary. As mentioned in the
answer to question 4, looking for motion or vascularity
may help in further characterization. Intravenous ultrasound
contrast agents will almost certaitlly help to sort
out many of these lesions by detecting the presence
or absence of enhancit1g components similar to the
principles used with CT or MR!.
In this case, the first itnage was of a cystic renal cell
cancer. Approximately 1 5% of renal cell cancers have
significant cystic components or are predominantly cystic.
Cystic changes may be due to hemorrhage or necro"
sis (often seen itl larger lesions), or to true cystic elements.

Front 209

Tra nsperineal views of the u rethra. The fi rst image i s in a coronal plane
and the second image is i n a sag ittal plane j ust to the left of the m idline.
1. What i s the differential diagnosis?
2. To what are the arrows POll1tll1g?
3 . The wall of this lesion is lined with what?
4. Are these abnormalities more commonly seen in men or in women?

Back 209

U reth ra l Diverti cu l u m
1 . The differential diagnosis i s urethral diverticulum or
periurethral abscess.
2. The arrows are pointing to the urethra.
3. The wall is lined with fibrous tissue, not
urothelium.
4. Urethral diverticulae are much more conunon it1
women.
Reference
Siegel C, Middleton WD, Teefey SA, et al: Sonography
of the female urethra. AJR A m J Roentgenol
1 998; 1 70: 1 269- 1 27 2 .
Cross-Reference
Genitourinary Radiology: THE REQUISITES, pp 244-
245.
Comment
These in1ages are obtained from a transperit1eal approach.
They show a fluid collection posterior to the
urethra. This is the most conunon location for a urethral
diverticulum. These diverticulae frequently dissect
around the left and right lateral aspects of the urethra.
It is believed that most female urethral diverticulae
develop from an infected paraurethral gland that erodes
it1tO the urethra and maintains a persistent patent neck
between the urethra and the cavity. Because these lesions
do not contain elements of the urethral wall, they
are really pseudodiverticulae.
Sonography is an excellent way to evaluate women
with suspected uretlu"al diverticulae. Sonography is better
tolerated than urethrography, and it is just as accurate.
In fact, ultrasound also visualizes periurethral lesions
that do not conununicate with the urethra, and ill
that respect it is superior to urethrography. MRI with a
transvagit1al or transrectal probe is also an excellent way
of evaluating patients with suspected urethral diverticulae.

Front 210

Power Doppler view of a TI P S s h u nt foll owed by a series of color
Doppler views and pu lsed Doppler waveforms from the main portal vein,
proximal stent, and mid stent. (See color plates .)
1. What are the important findings on these scans?
2. What happens to the portal vein velocity after a successful TIPS shunt?
3. What happens to the flow in the right and left portal vein after a successful TIPS shunt?
4. What is the significance of focal color Doppler aliasing in a TIPS stent?

Back 210

Stenosis of a TI PS Stent
1 . The power Doppler view shows incomplete color
fill-in of the stent due to hypoechoic tissue along
the wall of the stent. The portal vein waveform
shows an abnormally low velocity in the main
portal vein Oess than 30 cm/sec). The stent
waveforms show an elevated velocity in the mid
stent (greater than 1 90 cm/sec) and a discrepancy
of velocities in the proximal and in the mid stent
(velocity difference of greater than 1 00 cm/sec is
abnormal).
2. Normally, the portal vein velocity increases
following placement of a TIPS stent.
3. Usually, flow in the right and left portal veins
reverses after TIPS so that blood flow is directed
toward the stent.
4. Focal aliasing in a TIPS often identifies the site of
peak velocity.
References
Feldstein VA, Patel MD, LaBerge ]M: TIPS shunts: Accuracy
of Doppler US in determination of patency and
detection of stenoses. Radiology 1 996;20 1 : 1 4 1 - 1 47 .
Kanterman RY, Darcy MD, Middleton WD, e t a l : Doppler
sonographic findings associated with tnmsjugular intrahepatic
portosystemic shunt (TIPS) malfi.mction.
A]R Am ] RoentgenoI 1997; 168:467-472.
Cross-Reference
Ultrasound: THE REQUISITES, pp 3 1 -3 2 .
Cotnment
The transjugular intrahepatic porto systemic shunt
(TIPS) has become a well-accepted treatment of portal
hypertension and its complications. Although the technical
success rate for placement of TIPS shunts is greater
than 90%, a number of complications can cause shunt
malfunction. These include stenosis of the stent or hepatic
vein and shunt tlu·ombosis. The I -year primary
patency rate is 25% to 60%. However, with radiologic
intervention, the I -year patency rate increases to approximately
85%. Because of thiS, there is much incentive
to monitor these stents so that stenosis can be
detected and treated early, prior to development of
clinical symptoms. Although the use of ultrasound as a
screening test in this patient population is controversial,
multiple centers have shown that Doppler scanning can
be an effective means of following patients after TIPS.
Normally, the portal vein velocity increases after a
TIPS has been placed. We expect the post-TIPS portal
vein velocity to be greater than 30 cm/sec. Lower velocities
should raise the suspicion of a stenosis. Flow velocity
in the TIPS itself should be rapid. In our experience,
228
the normal range for stent velOCity is 90 to 1 90 cm/
sec. Higher and lower velocities should both raise the
suspicion of a stenosis. In the area of the stenosis,
the velocities increase . This increase can sometimes be
detected as a focal area of color aliaSing in the stent on
color Doppler scanning. Such areas should be sampled
with pulsed Doppler scanning so that velocities can be
measured from the waveform. Another sign of TIPS
stenosis is a change in direction of flow in the right and/
or left portal vein from toward the stent (hepatofugal) to
away from the stent 01epatopetal). This change in flow
direction tends to be a late finding.
We have found it difficult to rely on a single parameter
to make the diagnosis of TIPS stenosis. For instance,
a portal vein velocity of 28 cm/sec would not be an
indication for venography wlless other abnormalities
were present. Likewise, a slightly elevated maximum
stent velocity or a slightly depressed minimum stent
velocity would not be indications for venography if they
were isolated abnormalities. However, we have found
that combining the results of multiple parameters is
effective in predicting the need for venography and
intervention. It is worth noting that some centers have
had success in predicting stenosis by measuring only
the minimum stent velocity. These groups have found
that a stent velOCity below 50 to 60 cm/sec is a sign of
a failing stent.

Front 211

Views of the liver in fou r patients with the same condition.
1 . What are the two most likely diagnoses in these patients?
2 . Which image allows you to strongly suggest one diagnosis over the other?
3 . What history are these patients likely to have?
4 . What would you expect these lesions to look like on color Doppler?

Back 211

Hepatocellular Carcinoma
1. The most likely possibilities are metastatic disease
and hepatocellular carcinoma.
2. The last image shows tumor invading the adjacent
hepatic vein. This behavior is much more
consistent with hepatocellular carcinoma than with
metastatic disease.
3. All of these patients had a history of cirrhosis or
hepatitis.
4. Hepatocellular carcinoma is usually a hypervascular
lesion with disorganized, chaotic vascular pattern.
The ability to detect and visualize this vascularity
on color Doppler depends on the location of the
lesion. Superficial lesions are more successfully
interrogated with color Doppler than deep lesions.
Intravenous contrast agents improve the
sonographic analysis of vascularity in hepatocellular
cancer.
Reference
EI-Serag HB, Mason AC: Rising incidence of hepatocellular
carcinoma in the United States. N Engl ] Med
1 999: 340:745-750.
Cross-Reference
Ultrasound: THE REQUISITIES, pp 1 2 - 1 4.
Comment
Hepatocellular carcinoma (HCC) is the fourth most common
cancer in the world, and its incidence is increasing
in the United States. It affects patients with underlying
chronic liver disease. The most common causes are
alcoholic cirrhosis and chronic hepatitis B and C. Cirrhosis
develops during the first 1 0 years after transmission
in 20% of patients with chronic hepatitis C. Once
cirrhosis has occurred, HCC develops at a rate of 1 % to
4% per year in patients with chronic hepatitis C infection.
In cirrhosis, it is believed that regenerating nodules
undergo dysplastic changes and that dysplastic nodules
progress to HCC. In patients with end-stage liver disease
undergoing liver transplantation, tI1is progressive dysplastic
process results in HCC in approximately 25% of
patients with hepatitis B and C and in 10% of patients
with alcoholic cirrhosis. HCC is especially common in
Asia and sub-Saharan Africa because of the high incidence
of hepatitis B and C. Other predisposing causes
are hemochromatosis, liver flukes, exposure to aflatoxins,
Wilson's disease, and use of anabolic steroids.
As the images in this case show, the sonograpl1ic
appearance of HCC is quite variable. Lesions can be
hypoechoic (first image) or hyperechoic (large lesion
on last image). Some will have a target appearance
(small lesion on last image). Large lesions are more
230
frequently heterogeneous. Occasionally, lesions will be
mixed with organized nodular areas of increased echogenicity
in a background of decreased echogenicity (second
image), or vice versa. Calcification and cystic
changes occur but are distinctly unusual. Because cirrlIotic
liver parenchyma may attenuate the ultrasound
beam more than the tumor, increased through transmission
is occasionally seen posterior to HCC.
The pattern of HCC also varies and is dependent on
the population of patients being scanned. In groups of
patients who are being screened, tumors are detected
when they are relatively small and solitary. In Ullscreened
populations, tumors tend to be larger and are
often mutifocal. One pattern seen often in un screened
patients is a large, dominant mass with multiple smaller
satellite lesions (last image). A final pattern is a diffuse
infiltrative appearance that can affect entire segments
and lobes of ilie liver (third image). In many cases, the
lesions that infiltrate large portions of the liver are more
difficult to detect sonographically than the smaller lesions.
Sonograpl1ically visible portal vein invasion is also
common with the larger masses (see case 1 89). It is
believed that many of the satellite lesions are metastases
that arise from the tendency of HCC to invade the portal
veins. Hepatic vein invasion also occurs (last image) but
is less common than portal vein invasion.
In most patients, the key to the diagnosis of HCC is
the clinical history of chronic liver disease. Elevated
alpha-fetoprotein levels may suggest the diagnosis, but
false negative results are common, particularly with
small tumors. False positive results are also seen in
otherwise uncomplicated cirrhosis and during flares of
hepatitis. In a cirrhotic patient, HCC should be the
primary consideration whenever a solid liver mass is
detected on sonography. In my institution, such patients
undergo CT and in most cases subsequently have an
ultrasound guided percutaneous liver biopsy. My approach
is to start with fine needle aspiration (FNA)
using a 25-gauge needle. With experienced cytopathologists,
this can provide a diagnosis in approximately 50%
of cases. If the FNA is nondiagnostic, I proceed inlmediately
to a core biopsy using 1 8- to 20-gauge needles.
Many radiologists do not do FNA for HCC but rather
start initially with core biopsies.