Uterine Leiomyoma on MRI

Leiomyoma in a 28-year-old woman. Sagittal MR images in T2W (A), T1W (B) and post-contrast T1W (C) show a large, rounded, circumscribed mass in the anterior wall of the uterus (U) that pushes the bladder (B) anteriorly. The mass demonstrates T2 hypointensity, T1 isointensity and heterogeneous enhancement. 

Facts

• Most common uterine neoplasms with prevalence up to 40% of women of reproductive age
• Benign tumors of smooth muscle with variable amount of fibrous tissue
• Surrounded by pseudocapsule and supplied by one or two large vessels
• Greater than 90% from uterine body
• Classified on their position relative to uterine wall (submucosal, intramural or subserosal)

MR Imaging Findings

• Well-circumscribed mass
• Classic signal intensity: T1 isointensity, T2 hypointensity, variable enhancement
• If T1 hyperintense, think hemorrhage
• If T2 hyperintense, think cellular leiomyoma
• If no enhancement, think partially or completely infarcted leiomyoma

References

Hricak H. MRI of the pelvis: a text atlas

Hamm B, et al. MRI and CT of the female pelvis. 

Tibial Spine Fracture in Adults

A lateral knee radiograph of a 22-year-old man sustaining motor vehicle collision demonstrates an oval bone fragment (arrow) in the intercondylar region of the knee. There is complete separation between the fragment and the donor site with superior displacement of the fragment. Note hemarthrosis (asterisk).

Facts:

• Classically described in pediatric patients and considered the childhood equivalent of anterior cruciate ligament (ACL) ruptures in adults
• Forceful hyperextension of the knee resulting in avulsive force/tension on ACL, which inserts into the anterior tibial spine. Possibly with valgus stress or rotation. 
• In adults, most injuries occur in road-traffic accidents and are isolated
• Adults more likely to have associated tear of medial collateral ligament (MCL) or intra-articular fracture

Classification (Meyers and McKeever)

• Based on degree of displacement. Type II & III are most common
• Type I = incomplete avulsion of tibial spine without displacement
• Type II = incomplete avulsion with anterior elevation of the fragment
• Type IIIA = complete separation of fragment
• Type IIIB = rotated and comminuted fragment
• Generally, types I and II are managed conservatively while type III fractures are managed arthroscopically or with open reduction

References:

Kendall NS, et al. Fracture of the tibial spine in adults and children. J Bone J Surg [Br] 1992;74-B:848-52.

Rosen's Emergency Medicine - Concepts and Clinical Practice

Sarcoidosis on PET/CT

(A) MIP image from a PET/CT shows areas of FDG avidity in multiple lymph node stations including hilar, mediastinal, axillary, upper abdominal and groin regions. Note intense uptake of the spleen. 

(B&C) Axial fused PET/CT images show intense FDG uptake within thoracic, axillary nodes and spleen. 

PET/CT: Three patterns of sarcoidosis

1. Typical: Bilateral hilar uptake extending to the mediastinum with bilateral lung uptakes (PET and CT concordant lesions). This is found in the majority of cases (about 2/3)
2. Discrepant: Multiple foci of uptake in and outside chest, along with splenic uptake (PET and CT discordant lesions). Fewer lesions are seen on CT than on PET. This pattern is the 2nd most common and is indistinguishable from malignancy (esp. metastasis, lymphoma)
3. Multiple small FDG avid lung lesions: This pattern is similar to lung metastasis. Fortunately, it is the least common pattern. 

Our case: Biopsy-confirmed sarcoidosis involving the hilar, mediastinal, upper abdominal lymph nodes, and spleen. This follows the "discrepant" pattern (basically meaning that malignancy cannot be reliably distinguished)

References:

Alavi A, et al. Positron emission tomography imaging in nonmalignant thoracic disorders. Semin Nucl Med 2002;32:293-321.