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116 Cards in this Set

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What kind of technique do you want to use when performing a thoracic radiograph?
High kilovoltage peak (kVp)
-Chest has inherent contrast
-Goal is to spread out the grayscale
Low mAs
-Highest mA possible
-Shortest s possible (1/30 s)
True or false. It is a good idea to anesthetize the patient when performing a thoracic radiograph.
False! sedate the patient and avoid chest radiographs under anesthesia
How can you prevent atelectasis when taking a radiograph of an anesthetized patient?
Inflate the lungs several times before taking the radiograph
What are 2 ways to maximize non-manual restraint when performing a thoracic radiograph?
1) Use sandbands
2) Tape feet
What 2 projections should be used when performing thoracic radiographs?
2 orthogonal views
-L or R lateral
-Vd or DV
Do you take thoracic radiographs at peak inspiration or expiration?
Peak inspiration
What 2 views are best for outlining the lung vessels?
Left lateral
DV
When should 3 thoracic views definitely be taken?
If metastasis, mass, nodule, infiltrate or pneumonia is suspected,
-If in doubt take 3 views
Where should you center the beam when taking a lateral thoracic radiograph? What are the anatomical boundaries a thoracic radiograph?
On heart or caudal edge of scapula
-Include thoracic inlet to last rib
How should you position a dog when taking a lateral thoracic radiograph?
Pull legs forward
-The rib heads should be superimposed
How should you position an animal for a VD or DV thoracic radiograph? Where should the beam be centered? What are the anatomical boundaries?
-Legs pulled forward
-Center of beam on heart
-Thoracic inlet to last rib
How can you tell if an animal was correctly positioned when viewing a VD or DV thoracic radiograph?
Spine superimposed on sternum
-Teardrop-shaped dorsal spinous processes
What views should be taken when taking a thoracic radiograph of large animals?
2 lateral views-animal is standing
-Structures close to the film are well visualized and have sharp margins
-Structures further away will be magnified and less distinct
What view do you take to evaluate rib or chest wall lesions?
Oblique views
What view do you take to evaluate fluid filled structures or pleural fluid?
Horizontal beam
What are 2 reasons to always take thoracic radiographs at peak inspiration?
1) Maximize lung contrast
2) Reduced one variable
On an inspiratory lateral thoracic view, where is the caudo-dorsal aspect of the lung located?
Caudal to T12
Taking a lateral thoracic radiograph upon inspiration cause increased aeration of the ______ lung lobe.
Accessory
Taking a lateral thoracic radiograph on inspiration is important for separation the _______ and_______.
Heart silhouette & diaphragm
Where is the diaphragmatic cupula normally located on an inspiratory VD or DV view?
Caudal to mid T8
Where are the lung tips normally located on an inspiratory VD or DV view?
Caudal to T10
How can you tell if a thoracic radiograph is dark enough?
Should be able to see individual vessels
How can you tell if a thoracic radiograph is too dark?
Should be able to see peripheral pulmonary vessels with naked eye
How do you correct minor bad exposure on a thoracic radiograph?
Change kVp +/- 10% (usually 5-8 kVp)
How do you correct major bad exposure on a thoracic radiograph?
Double or half mAs
What are 5 reasons to retake thoracic radiographs?
1) Under- or overexposed
2) Not at peak inspiration
3) Poor positioning
4) Part of the thorax is omitted
5) Motion
The likelihood of a diagnosis via a thoracic radiograph is strongly dependent on _____.
Quality-even if you send them to a radiologist
How is the heart usually shaped on a right lateral radiograph?
Oval or egg shaped
How are the diaphragmatic crura arranged on a right lateral projection?
Crura are parallel
True or false. There may be air in the fundus of the stomach on a left lateral projection.
False, that's on a right lateral projection
What lateral projection is better to visualize the right and left cranial pulmonary veins and arteries?
Left lateral, in a right lateral projection they overlap
How is the diaphragmatic crura position in a left lateral recumbency?
Left diaphragmatic crus is more cranial
-See a V shape in diaphragm
What view do you want to take to evaluate the caudal vena cava?
Left lateral projection
Do you want a right or left lateral radiograph to evaluate the apex of the heart?
Right lateral because apex of heart tends to be displaced from the sternum
What shape is the heart on a left lateral projection?
Heart tends to be more circular in shape
Which lateral projection allows better evaluation of relative vessel size?
Left lateral projection
What view do you want to visualize changes in the aorta and greater vessels?
Dorsal recumbency
What view do you want to take to visualize the accessory lung lobe?
Dorsal recumbency
-Less aerated due to the cranial displacement of diaphgram in DV
What shape is the heart in sternal recumbency? How is it positioned
Tends to be more oval as it is in a more upright position
-Often displaced to the right due to the cranial position of the diaphragm
What view do you want to visualize the caudal pulmonary vessels and bronchi?
Sternal recumbency as they are magnified and more perpendicular to the x-ray beam
What are the 4 structures (groups) to be evaluated on a thoracic radiograph?
1) Heart & great vessels (middle mediastinum)
2) Cranial & caudal mediastinum
3) Lungs including pulmonary vessels & pleura
4) Extrathoracic structures
What are 5 locations you can exam for abnormalities on a thoracic radiograph?
1) Heart & great vessels
2) Mediastinum
3) Lungs & upper airways
4) Pleural cavity
5) Diaphragm & thoracic wall
What are 4 ways that a thoracic radiograph can be used to evaluate the heart (what can be diagnosed)?
1) Diagnosing heart enlargement
2) Diagnosing heart failure
3) Differentiating heart failure from lung disease
4) Diagnosing specific heart diseases
The cardiac silhouette delineates the margins of the ______.
Heart/pericardium
True or false. You can determine wall thickness or chamber size of the heart on a thoracic radiograph
False
Is the canine or feline cardiac silhouette more consistent?
Feline cardiac silhouette, canine cardiac silhouette varies widely
-Breed
-Size
-Body type
True or false. Cardiac disease in equine patients is usually diagnosed radiographically.
False, ultrasound is the technique of choice
-Hypoperfusion
-Hyperperfusion
What is different about the heart in a boston terrier and sheltie?
Increased sternal contact
What forms the three knuckles on the heart in a VD projection?
From right (of patient) to left:
Right auricle
Aortic outflow tract
Pulmonary outflow tract
What 3 structures are located on the dorsal 1/3 of the cranial border of the heart?
1) Right auricle
2) Ascending aorta
3) Main pulmonary artery
What 2 structures are located on the ventral 2/3 of the cranial border of the heart?
1) Wall of RV
2) Pulmonary outflow tract
What is located on the dorsal 1/3 of the caudal border of the heart?
Left atrium
What is located on the ventral 2/3 of the caudal border of the heart?
Left ventricle
What is located at 11:00-1:00 according to the clock face analogy?
Aortic arch
What is located at 1:00-2:00 according to the clock-face analogy?
Main pulmonary artery
What is located at 2:30-3:00 according to the clock-face analogy?
Left auricle
What is located at 2:00-5:00 according to the clock face analogy?
Left ventricle
What is located at 5:00-9:00 according to the clock face analogy?
Right ventricle
What is located at 9:00-11:00?
Right atrium
Where is the tracheal bifurcation located on a DV/VD view?
Left atrium
What is a normal vertebral heart score in the dog? Cat?
Dog 9.7 +/- 0.5
Cat 7.7 +/- 0.3
How do you calculate a vertebral heart score?
Ventral aspect of trachea to tip of heart, not including pericardial fat, then maximum width of heart at about 90 degree to other axis, then add lengths in vertebraes
How large is a normal feline heart on a lateral projection? DV?
2-2.5 IC spaces wide
2/3 DV thoracic height
How do old cat hearts appear on radiographs?
As cats age, they can develop "lazy heart" where the heart has increased sternal contact, a tortuous aorta, and an aortic bulge seen in VD/DV projections
Where is the apex of the heart normally located on a DV/VD projection of a cat?
Left side
The heart is more elongated on a VD or DV projection of a cat?
VD
the normal width of the heart takes up how much of the chest on a DV/VD projection?
1/2 to 2/3 width of chest
How is the heart oriented in deep-chested dogs such as dobermans, collies and irish setters on a lateral projection and DV/VD projection?
Lateral: upright orientation of heart, perpendicular to the spine
DV/VD: Circular to ovoid heart
How wide should a heart normally be in a deep-chested dog such as dobermans, collies and irish setters? Height in DV?
2.5 IC spaces wide
2/3 DV height
Where should the apex of the heart be in a DV/VD projection of a deep-chested dog?
Median to slightly left of midline
How is the shape of the heart different in a DV/VD projection of a dog with intermediate conformation such as a German shepherd or Labrador retriever?
More elongated
Where is the apex of the heart normally located in a VD/DV projection of a dog with an intermediate conformation?
To the left of midline
How is the heart shaped in a dog with a shallow-chested conformation such as a Boston terrier or bulldog on a lateral projection? How wide? Height on DV?
Heart is shorter, more round
3-3.5 IC spaces wide
2/3 or less DV heigh
In which chest conformation of canines does the heart have the most sternal contact?
Shallow-chested conformation
How is the heart shaped in a shallow-chested dog on a DV/VD projection? Where is the apex located?
Heart round to elongated
Apex shifted to the left
-Short distance from thoracic inlet to cupola of diaphragm
What's an example of the fact that normal heart size does not mean normal function?
Dilated cardiomyopathy and heart failure can be a normal sized heart
What is the definition of microcardia?
Cardiac silhouette < 2 1/2 intercostal spaces wide
What are 2 supporting Roentgen signs of microcardia?
1) Pulmonary hypoperfusion
2) Consistently small caudal vena cava
-May see heart elevated from sternum
What are 3 differentials diagnoses for microcardia?
1) Dehydration
2) Shock
3) Hypoadrenocorticism
Normally the caudal vena cava is approximately the same as ______.
Aorta
The caudal vena cava is variable with ______ and ________.
Cardiac cycle and respiration
What are 2 differential diagnoses for a small caudal vena cava?
1) Hypovolemia
2) Shock
What is a differential diagnosis for an enlarged caudal vena cava?
Congestive right sided heart failure
Where is the aortic arch located?
11:00-1:00 (VD/DV)
What are 2 locations/causes for segmental enlargement of the aorta?
1) Proximal descending aorta
-Ductus arteriosus
2) Aortic outflow tract stenosis/PDA
According to the clock analogy where is the main pulmonary artery segment located?
1:00-2:00 region (DV,VD)
What are 2 causes of enlargement of the main pulmonary artery segment (1-2 o'clock)?
1) Pulmonary hypertension
-Heartworm disease
2) Pulmonary outflow tract stenosis
How are the pulmonary vessels arranged on a lateral view? How big should they be?
Pulmonary artery is dorsal
Pulmonary vein is ventral
-Bronchus in b/w
-Veins are ventral & central
-Should be 0.5 to 1.0 width of 4th rib
How are the pulmonary vessels arranged on a VD/DV? How big should they be?
Pulmonary artery is lateral
Pulmonary vein is medial
0.5 to 1.0 width of 9th rib
What does it mean if you see global enlargement of the heart?
Pericardial effusion
-Always has rounded caudodorsal border
-Ovoid shape
Is it a better prognosis to be able to detect global enlargement of the heart or left atrial enlargement?
Global enlargement is NOT good
True or false. The ability to evaluate MILD general heart enlargement on radiographs is important.
False, not important, not reliable, diagnosis of the presence of heart disease is made by clinical methods, NOT radiography
Radiography is used to help diagnose _________.
Failure
Do you take thoracic radiographs of a congenital disease for diagnosis or prognosis?
Prognosis
-Larger the heart and more changes of vessels=worse prognosis
What are 2 differential diagnoses for severe generalized cardiomegaly/globoid heart?
1) Pericardial effusion
2) Dilated cardiomyopathy
-Medium to large size dogs
3) PPDH
What are 2 differential diagnoses for mild/moderate generalized cardiomegaly?
1) Mitral/tricuspic valve endocardiosis (small breed dogs)
2) Dilated cardiomyopathy (large breed dogs)
What is a differential for left atrial enlargement in a dog ?
Mitral endocardiosis (small breeds)
What are 2 differential diagnoses for right heart enlargement in a dog?
1) Tricuspid endocardiosis
2) Heart worm disease
What are 2 differential diagnoses for cardiomegaly in a cat?
1) Hypertrophic cardiomyopathy
2) Dilated cardiomyopathy (rare)
What heart condition in a cat can still have a normal sized heart?
Hypertrophic cardiomyopathy-radiographs are insensitive for HCM
What should you do if you detect a heart murmur in a young animal?
Should refer the animal and send the radiographs with the referral
What are 3 changes in the shape of the heart should you look for?
1) Left atrial enlargement
2) Reverse-D for cor pulmonale (heartworms)
3) Post-stenotic dilations in congenital disease
What is the most common acquired cardiac disease?
Mitral regurgitation
What dogs have the highest prevalence of mitral regurgitation?
Middle aged and old small-medium sized breeds
-Not a disease of young dogs
What causes mitral regurgitation?
Thickened mitral valve
What are 3 signs of a mitral regurgitation on a lateral projection?
1) Dorsal displacement of trachea
2) Increase in proportion of the DV diameter of the thorax
3) Straightening of the caudal border of the heart
What are 3 typical signs of mitral regurgitation on a VD/DV?
1) Double opacity sign
2) Separation of the main stem bronchi
-"Bow-legged cowboy"
3) Left auricular enlargement
True or false. You can rule out divergence of the mainstem bronchi if you do not see the "bow legged cowboy".
False, doesn't always cause divergence of main stem bronchi
What 2 structures can be involved in the bow-legged cowboy?
1) Tracheal bifurcation (carina)
2) Main bronchi
What is located between the main stem bronchi?
Left atrium
What is a sign of left atrial enlargement on a lateral projection?
Straightening of the caudal border of the heart and main stem bronchi is pushed dorsally (can lead to compression of main stem bronchi if severe
What are 3 typical signs of mitral regurgitation on a VD/DV?
1) Double opacity sign
2) Separation of the main stem bronchi
-"Bow-legged cowboy"
3) Left auricular enlargement
True or false. You can rule out divergence of the mainstem bronchi if you do not see the "bow legged cowboy".
False, doesn't always cause divergence of main stem bronchi
What 2 structures can be involved in the bow-legged cowboy?
1) Tracheal bifurcation (carina)
2) Main bronchi
What is located between the main stem bronchi?
Left atrium
What is a sign of left atrial enlargement on a lateral projection?
Straightening of the caudal border of the heart and main stem bronchi is pushed dorsally (can lead to compression of main stem bronchi if severe