What does the alpha angle suggest in this hip?

You are shown two MRI images. One is a standard orthogonal coronal with a line through it. This shows the angle of acquisition to evaluate the alpha angle. The second image is the axial oblique with the lines used for alpha angle measurement. Questions:

  • What is a normal alpha angle?
  • What does an abnormal alpha angle suggest?
  • Is an abnormal alpha angle pathognomonic of a symptomatic disease process?

Answers:

  • Normal alpha angle is 55 to 60 degrees or less.
  • Increased alpha angles suggest cam impingement syndrome or impingement syndrome type 1.
  • The yellow line in the second image is placed from the center of the femoral head to the junction of the medial transition of the upper femoral head to the bump. The green line bisects the center of the femoral head, neck, and trochanteric region as demonstrated on the axial oblique image.
  • Athletic, large men often have abnormal alpha angles in the absence of symptoms. Therefore, the alpha angle is not pathognomonic of symptomatic cam impingement, only suggestive.
  • For more orthopaedic case review, head to MRI Online.

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Figuring out T stage with limited imaging

This 87-year-old man presents with two cancers. Note they are unrelated and not the result of one cancer spreading to another organ. What are the two cancers? Advanced questions: Can you posit the T stage of cancer #1 from limited imaging? How valuable is diffusion imaging in the prostate as an example?

Answer: Prostate and rectal cancer. You can posit the T stage of the prostate lesion on the left (arrow) as T3b as there is seminal vesicle invasion. The diffusion image is especially valuable for mass-like lesions over 3 millimeters in size in the prostate peripheral zone. Many “benign’ or nonaggressive central zone masses in the prostate will have mild diffusion restriction. For more prostate staging resources, visit MRI Online.

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What sport has a squeeze play? And where is the squeeze play on this cardiac MRI?

BASEBALL!

The squeeze play is seen in baseball. It’s used when a batter bunts the ball in an attempt to bring his teammate on third base home to score a run. It is an exciting play, as the team initiating it is often looking for a tying or winning run late in a close game.

Where is the squeeze play here on axial T1 cardiac MRI?

The squeeze play here is a fatty tumor compressing the superior vena cava. The vena cava is normally round. Here, it appears squeezed or slit-like (second image, arrow). This could lead to superior vena cava syndrome. Surveillance recommended every 6 months. The third MR image shows signs of right ventricular dysplasia. The anterior right ventricle is lobulated, irregular and exhibits sparse fat signal.

For more case review resources, head to MRI Online.

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ADEM or MS? How to differentiate between two favored diagnoses

This 15-year-old presents with blurred vision and white-matter lesions on axial FLAIR MRI. Acute disseminated encephalomyelitis (ADEM) and multiple sclerosis (MS) are the two favored diagnoses, so what questions would you ask to differentiate?

You should ask: How long has this symptom been present? Is it clinically monophasic or polyphasic? Was there a recent upper respiratory infection (URI) or vaccination? A longer symptom time favors MS. Monphasic favors ADEM. Polyphasic waxing and waning clinical course favors MS. History of URI, viral infection or recent vaccination favors ADEM. In this case, ADEM is favored due to the patient being an adolescent. Other factors include the extension into the parasagittal genu of the corpus callosum (left greater than right forceps minor). The fact that this is a single monophasic episodic event (blurred vision for two weeks) also favors ADEM.

For more neuro case review, check out MRI Online.

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A meniscus case with some dangerous verbiage

This 12-year-old female presents with left knee pain, and the clinician alleges meniscal tear. The initial read was noncommunicating tear, but is this the proper call? You are shown four gradient echo sagittal water-weighted images and one sagittal T1.

Sagittal

Sagittal

Sagittal

Sagittal

Sagittal T1

 

No, this was not the proper call! Save the whales and the menisci. It’s a 12-year-old. High signal due to vascularity and overuse is not uncommon in this age group. A meniscectomy in a 12-year-old is a DISASTER in most cases in the long term. This signal fades in meniscus inner third and is most conspicuous in the outer one-third red-red zone. It is also window framed by dark signal, the meniscus has normal size and shape, the signal in the meniscus is ill-defined and not very bright on T1 and finally T2* gradient echoes always tend to overestimate signal in menisci compared to proton density SPIR MRI. Patient has patellofemoral maltracking as cause of pain anyway. There is NO meniscal tear.

For more meniscus content, head to MRI Online.

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What do your grill and this prostate case have in common?

What do your grill and this prostate case have in common? The first image is a prostate axial MRI T2. Can you name the sign? There is also an axial diffusion and ADC parametric map. Gleason score is probably greater than what number?

“Charcoal erasure sign” of malignancy (axial T2 arrow). With erasure sign (on axial T2 the normal anatomy is “smeared away,” by hypointensity), broad capsular contact anteriorly (a worrisome sign for capsular invasion), and pronounced diffusion restriction. The Gleason score is likely greater than 6. You use charcoal in your grill and you have the charcoal erasure sign in the anterior prostate as a sign of malignancy.

For more interesting prostate case review, visit MRI Online.

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Ten-Year-Old With Hearing Loss: What Are The Tipoffs?

10-year-old male with bilateral hearing loss and a bout of meningitis. You are shown one sagittal CT reconstruction. What is the diagnosis? What are some clinical tipoffs? Be sure to think about your answer, then scroll below to see mine.

Cystic cochleovestibular anomaly.

Clinical tipoffs – Congenital deafness plus recurrent bacterial meningitis.

ProScan Pearl: Remember in bilateral congenital deafness to always check the thyroid (Pendred’s syndrome).

For more comprehensive neuro case review, visit MRI Online.

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A subependymoma that’s easy to miss

This 37-year-old female presents with a 4th ventricle subependymoma. You could sure miss this!

Sagittal T1 FLAIR

Axial T2 FLAIR

Coronal T1

 

The inferior 4th ventricle is the most common location followed by the lateral ventricle (over 90 percent are in 4th or lateral). They may not enhance, but the 4th ventricular ones are more likely to, as seen in this case. Subependymoma is seen in an older patient demographic than ependymoma. Most subependymomas under 2 centimeters are asymptomatic.

To check out more neuro case review, head to MRI Online.

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Elbow: No known injury-but missing component of lateral stabilizers

This 65-year-old presents for an elbow MRI with no known injury. Can you name the components of lateral stabilizers and what is missing? Let the arrows be your clue.

 

Dynamic stabilizers are musculotendinous extensors and these are ruptured from their origin. Static stabilizers include:

  • Lateral ulnar collateral ligament- intact (LUCL – double arrows, image one)
  • Annular ligament (not seen)
  • Accessory annular ligament (not seen)
  • Lateral capsule (torn-arrow, images two and three)
  • Proper radial collateral ligament (torn-arrow, images two and three).

For additional case review resources, check out MRI Online.

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Known tibia diagnosis, but still questions about management

This 13-year-old presents with a tibia lesion. You know the diagnosis. What should you do to recommend management?

The diagnosis is osteoid osteoma. Treat the pain with aspirin or anti-inflammatory agents. But, these lesions will burn out and should not be lasered, removed, etc. Save the whales! Save the shins of our children! Leave osteoid osteomas alone. And check out additional valuable case review on MRI Online.

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