Spectrum of Fat-containing Soft-Tissue Masses at MR Imaging: The Common, the Uncommon, the Characteristic, and the Sometimes Confusing.

Fat-containing tumors are the most common soft-tissue tumors encountered clinically. The vast majority of fat-containing soft-tissue masses are benign. Lipomas are the most common benign fat-containing masses and demonstrate a characteristic appearance at magnetic resonance (MR) imaging. Less common benign soft-tissue masses include lipoblastoma, angiolipoma, spindle cell lipoma/pleomorphic lipoma, myolipoma, chondroid lipoma, lipomatosis of nerve, lipomatosis, hibernoma, and fat necrosis. Well-differentiated liposarcomas (WDLPSs)/atypical lipomatous tumors (ALTs) are locally aggressive soft-tissue masses that do not metastasize. Biologically more aggressive liposarcomas include myxoid, pleomorphic, and dedifferentiated liposarcomas. At MR imaging, lipomas typically resemble subcutaneous fat but may contain a few thin septa. The presence of thick, irregular, enhancing septa and nonfatty soft-tissue mass components suggests liposarcoma rather than lipoma. However, benign lipomatous lesions and WDLPS/ALT often have overlapping MR imaging findings. Distinguishing WDLPS/ALT from a benign lipomatous lesion or from fat necrosis at imaging can be challenging and often requires histologic evaluation. We present the spectrum of fat-containing masses, using the World Health Organization classification of adipocytic tumors, with an emphasis on commonly encountered lesions, characteristic MR imaging findings associated with specific tumors, and overlapping MR imaging findings of certain tumors that may require histologic sampling. We also briefly discuss the role of molecular markers in proper characterization and classification of fat-containing soft-tissue masses. (©)RSNA, 2016.

Radiographic and CT Assessment of Reduction of Calcaneus Fractures Using a Limited Sinus Tarsi Incision.

BACKGROUND: The lateral extensile incision for fixation of displaced intra-articular calcaneus fractures allows for fracture reduction but has been associated with high rates of soft tissue complications. This has prompted a search for less invasive methods of fracture fixation. The purpose of the present study was to determine the adequacy of reduction and rate of complications associated with operative fixation of calcaneal fractures using a limited sinus tarsi approach. METHODS: A limited sinus tarsi incision with plate fixation was utilized for treatment of 39 displaced intra-articular calcaneal fractures in 35 consecutive patients as part of a single surgeon series. Imaging assessment of previously described fracture displacement measures was undertaken in preoperative and postoperative radiographs and CT. A retrospective chart review was conducted to identify postoperative complications. RESULTS: Mean preoperative Bohler angle measurement was 7.7 (range, -26.0 to 30.0) degrees and the mean final postoperative standing Bohler angle was 25.5 (range, 12.3 to 37.7) degrees. Postoperative CT demonstrated that subtalar articular reduction was within 2 mm of anatomic in 91% of patients. There were 2 instances of superficial wound dehiscence (5.1%) and 1 deep infection (2.6%) that required debridement and complete hardware removal. Visual analog score (VAS) for pain averaged 3 of 10 in the 32 available patients at 1-year follow-up. Eight of these patients (25%) reported no pain (0/10) at final follow-up. CONCLUSION: Operative fixation of displaced intra-articular calcaneal fractures utilizing the limited sinus tarsi approach resulted in acceptable fracture reduction and a low rate of complications. LEVEL OF EVIDENCE: Level IV, retrospective case series.

High-resolution 3-T MRI of the fingers: review of anatomy and common tendon and ligament injuries.

OBJECTIVE. With high-resolution 3-T MRI, the complex anatomy of the fingers can be imaged in exquisite detail to provide an accurate diagnosis of clinically important ligament and tendon injuries. CONCLUSION. We present our 3-T MRI protocol using a dedicated hand-and-wrist coil and review normal MRI anatomy of the fingers. We emphasize a systematic approach to the interpretation of finger MRI examinations and illustrate this approach with examples of tendon and ligament abnormalities.

MRI of the posterolateral corner injury: a concise review.

The posterolateral corner of the knee represents a complicated area of anatomy and function. Failure to recognize injury to the posterolateral structures in the acute setting can result in long-term disability. Magnetic resonance imaging (MRI) provides a noninvasive evaluation of such structures. A systematic and simplified approach to the MRI evaluation of posterolateral corner injury can aid in diagnosis and subsequent surgical consideration.