Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
what are the 5 major physical densities from least dense to most dense. which appears darker and lighter on an X-ray
|
1. air
2. fat 3. water (muscle) 4. bone 5. metal Brightest |
|
|
what are the most common positions for X-rays in general
|
AP
Lateral Oblique |
|
|
what are the ABC's of X-ray eval
|
A-Alignment
-joint spaces -identify accessory bones if present -trace the bones B-bone density -look for different densities C-cartilage spaces -uniform, narrow S - soft tissues |
|
|
what is the approach to general X-ray eval
|
1. ABC'S
2. Id the view 3. orient the image (Left or right) |
|
|
CT scan
-what does it stand for -why would you use it |
-Computed Tomography
-trauma, subtle or complex fractures, spine, pelvis -infection -vascular, aneurysms |
|
|
why CT
why Xray why MRI |
CT and Xray for bone
MRI for soft tissue structures |
|
|
different MRI signal intensities, what shows up brighter on each
|
T1 = fat is brighter, better for bone and muscle
T2 = CSF and water is brighter, better for swelling or disc buldges |
|
|
what are the general positions for MRI
|
sagittal
coronal axial oblique |
|
|
what are the X ray views for the knee
|
AP
Lateral Tangential patellar/"Sunrise" view |
|
|
what are the MRI common views for the knee
|
Sagittal
axial coronal |
|
|
what is the knee MRI reading process
|
1. bone marrow
2. synovium 3. articular cartilage 4. collaterals 5. cruciates 6. menisci 7. extensor mechanism |
|
|
what is a bone marrow infarct, edema, and joint fluid common to knee pathology
|
bone marrow edema is often the result of trauma and there is a strong likelyhood of fracture
bone marrow infarcts can be found in individuals who use steroids or work in high pressure environments (divers) |
|
|
when do you order knee imaging
|
-patient is >55 yo
-tenderness over fibular head -tenderness over the patella -inability to flex the knee 90 deg -inability to bear weight both immediately and in the ED (4 steps) |
|
|
on the lateral knee x-ray what will you look for
|
-the medial femoral condyle is superimposed on the lateral femoral condyle
-length of patella and length of patella ligament should be equal +- 20% (patella alta=longer tendon=dislocation or patella baja=shorter tendon) -patellar fracture -knee dislocation -osgood-schlatter disease (inflammation from muscle pulling at the attachment of the bone) |
|
|
how much knee flexion for lateral knee x-ray? sunrise xray?
|
lateral = ~20
sunrise = ~45 |
|
|
how do you orient the sunrise xray view?
|
the lateral patella is thinner
|
|
|
what do you look at on the sunrise knee xray view?
|
-sulcus angle from apex of both femoral condyles is about 140 deg (greater=sublux patella, less=pain)
-patellar fracture -patellar dislocation |
|
|
what do you look for on the AP view of knee Xray
|
-femoral fractures, tibial fractures,
-joint space -genu varum, valgum -bone density (giant cell tumor) |
|
|
what to look for during knee MRI reading of bone marrow
|
-low on T1
-High on T2 -high on most fat supporessed sequence -look for abnormal bone density, or tumor, giant cell tumor common in tibia |
|
|
what to look for during knee MRI reading of synovium
|
(is there swelling)
-low on T1 -High on T2 -high on most fat supporessed sequence -bakers cysts=popliteal fluid accumulation behind the knee, usually after meniscus tear |
|
|
what to look for during knee MRI reading of articular cartilage
|
(osteochond/defects-black line)
-bright on fat suppressed sequences -low to intermediate signal on T1 and T2 synovial osteochondromatosis-loose bodies: benign, self-limiting cartilage containing tumor characterized by pain, swelling, and loss of ROM -appear intermediate to low on T1 -high on T2 -visible on Xray if ossified -look like little balls floating around in the synovium |
|
|
what to look for during knee MRI reading of extensor mechanism
|
(patellar tendonitis)
-patellar ligament should look like a thin black line, could indicate swelling if line is thicker fibrocartilage, ligaments, and tendons appear: -low on T1 -low on T2 -low on fat suppressed sequences -patellar tendon tear -jumpers knee (assessment of the quad tendon and patellar tendon can be done with sagittal and axial images) -patellar tendinopathy -quads tendon tear -osgood-schlatter's (pulling on the tibial tuberosity) easily seen on sagittal images complete tears are high signal intensity with tendon separation |
|
|
what to look for during knee MRI reading of collaterals
|
MCL/TCL and LCL/FCL
MCL: divided into layers, first layer is the superficial fibers, second layer is the bursa and fat, third layer is the deep fibers or the capsular ligament -superficial fibers run from the medial femoral condyle and pass distally to insert 5 cm below the joint line and posterior to the pes anserine tendons. -the bursa can become inflamed and enlarged and should not be confused with a ligament tear. -the deep ligament is attached to the capsule and the mid portion of the medial meniscus -the MCL should be viewed on three consecutive coronal silces -on coronal MRI can see all thre layers LCL/FCL: -runs from the lateral femoral condyle to the fibular head -does not blend intot he joint capsule or the meniscus as does the MCL -less prone to injury compared to the MCL -more like a capsular thickening -well defined cord -tear looks like a PCL tear -runs anterior to the biceps femoris on the sagittal view |
|
|
what to look for during knee MRI reading of cruciates
|
PCL and ACL
-best seen on T2 image ACL -multiple fibers that will show up as linear areas of low signal intenisty, broad band structure -high signal intensity will be seen on acute lesions. -chronic tears are seen as areas of intermediate signal intensity -70% of ACL tears result in other intraarticular damage PCL -thicker and has more uniform low signal intensity -tears are usually mid substance -appears hook like you want a shot where you can see both ligaments making an X |
|
|
what to look for during knee MRI reading of menisci
|
normal meniscus looks like a wedge
intra-meniscal signal reaching an articular surface indicates a tear (higher meniscal intensity has to reach the articular surface, bright signal where tear is) look for the bow tie sign = good |
|
|
what are the different types of meniscus tears?
|
1. degenerative - a horizontal tear
2. linear tear 3. bucket handle -most commonly missed tear, most likely to cause locking of the knee -scarring may occur in the intercondylar notch -absense of bow tie sign (1/2 of bow tie) -double PCL sign 4. flip -posterior horn displaced anteriorly -superior surface becomes inferior -medial or lateral 5. meniscus cyst 6. discoid meniscus |
|
|
degenerative joint disease of the knee
|
-cartilage loss
-meniscal tear (often horizontal) -osteophytes -osteochondral defect OCD -meniscal subluxation |
