[Correlation of MR imaging features and histopathology of synovial sarcoma]

Magnetic resonance imaging (MRI) is the best detective technique for soft tissue tumors, but it lacks specific imaging signs to distinguish various tumors. The synovial sarcoma is observed more frequently in soft tissue tumors. This study was to evaluate correlation of MRI features and histopathology of synovial sarcoma, and to improve the diagnostic accuracy of synovial sarcoma by MRI.

Twelve patients with synovial sarcomas were confirmed by operation and histopathology, included 9 men, and 3 women, aged from 35 to 50 years. Ten tumors located in lower limbs, 2 located in upper limbs. MRI was performed with a 0.5T magnet system. All images were obtained through T1-weighted imaging (T(1)WI), and T(2)-weighted imaging (T(2)WI), and some images were obtained by T(2)WI with stair. All patients received enhanced scan after Gd-DTPA injection. Radiological and histopathologic findings were compared.

All tumors located in the places closed to joints, 2 invaded into joints, 3 invaded into bones. On T(1)WI, 12 tumors displayed signal intensity similar to that of skeletal muscle, and 3 showed cystic high intensity areas similar to that of subcutaneous fat. On T(2)WI, 6 tumors showed hyper-, iso-, and hypointense areas relative to fat constituting a triple signal intensity; 6 were multilocular, 3 were irregular, 3 were circular or elliptical. The septa configurations were seen in 5 tumors, fluid-fluid level sign was seen in 1 tumor. Maximum diameters of tumors ranged from 3 to 13 cm. All tumors enhanced asymmetrically after Gd-DTPA injection. On histological examination, 7 were poorly differentiated monophasic type, 3 were well differentiated monophasic type, 2 were biphasic type, 6 had old and/or fresh hemorrhage, 5 had large necrosis areas, 2 had calcification.

MRI manifestation is specific in synovial sarcoma, and may be correlated with histopathology of synovial sarcoma.