SYNOVIAL SARCOMA - FREQUENCY OF NONAGGRESSIVE MR CHARACTERISTICS

Purpose: Our objective was to examine the MR characteristics of synovi al sarcoma and determine the frequency of a nonaggressive imaging appe arance. Method: Fifteen patients with histologically confirmed cases o f synovial sarcoma and prior MR examinations were seen. Retrospective analysis of imaging features included assessment of size, margins, hom ogeneity, internal architecture, T1- and T2-weighted signal intensitie s, and bone invasion. Results: Five of 15 patients (33%) had well circ umscribed, homogeneous lesions with a mean length of 4.8 cm. The T1-we ighted signal intensity was either isointense to muscle or greater in signal intensity than muscle. The T2-weighted images demonstrated sign al intensity equal to or greater than fat. The remaining 10 lesions we re larger (mean length of 11.3 cm) with mild to complex levels of inho mogeneity and margins that varied from well circumscribed to infiltrat ing. Conclusion: There are two sets of MR features seen with synovial sarcoma. Small lesions of similar to 5 cm can demonstrate a nonaggress ive appearance with well circumscribed margins and homogeneous signal intensity. These tumors could be confused with benign lesions, resulti ng in inappropriate surgical intervention like excisional biopsies thr ough transverse incisions. This would make future surgery more difficu lt. Larger lesions tend to be more heterogeneous in signal intensity.