MR Imaging Findings of Synovial Sarcoma: Emphasis on Signal

ABSTRACT

PURPOSE: To determine the MR imaging findings of synovial sarcoma, with emphasis on the signal characteristicsof pathologically correlated T2-weighted images. MATERIALS AND METHODS: MR images of 14 cases ofpathologically-proven synovial sarcomas were retrospectively reviewed and correlated with the histopathologicfindings. We analyzed the signal intensity of T1- and T2-weighted images and the incidence of triple signalintensity, and evaluated the frequency of fluid-fluid levels, internal fibrous septa, calcification, the invasionof bone or neurovascular bundles and the involvement of joint capsules, as well as the size, location and marginof the tumors and pattern of contrast enhancement. RESULTS: Necrosis, cystic change or hemorrhage was suggested in11 cases, ten of which showed triple signal intensity, and in all cases, was pathologically confirmed. Fluid-fluidlevels were found in three cases and internal septa in ten. In four cases, maximum diameter was less than 5cm, andin nine, was greater than this. No mass was detected in one case. The tumor was located in the low extremity(n=9),pelvic girdle and hip joint area(n=2), scapular(n=1), shoulder joint area(n=1), and scalp(n=1). Eleven casesshowed a relatively well-defined margin and nine showed lobulation. Except in the area of necrosis and cysticchange, the pattern of contrast enhancement was diffuse and inhomogenous. Bony invasion was detected in two cases,neurovascular encasement in four, calcification in four, and joint capsule invasion in four. CONCLUSION: OnT2-weighted images, synovial sarcoma frequently showed triple signal intensity and internal septa with fluid-fluidlevels ; this was induced by cystic changes due to necrosis and hemorrhage.