Synovial cysts of the lumbosacral spine: diagnosis by MR imaging.

Intraspinal synovial or ganglion cysts are uncommon lesions associated with degenerative lumbosacral spine disease. CT usually reveals cystic lesions adjacent to a facet joint, and they may show calcification. MR imaging of four surgically confirmed cases of intraspinal synovial cysts revealed subtle signal changes compared with CSF. Short TR/TE images showed the lesions to be slightly hyperintense in three cases and isointense in one case. Long TR/TE sequences revealed a hyperintense appearance in two cases and a hypointense appearance in the others. A peripheral rim of decreased signal on long TR/TE images probably reflects fine calcification or hemorrhage in the margins of the cysts. The multiplanar and contrast characteristics of MR make this technique well suited to the diagnosis of herniated disk, degenerative facet disease, and synovial cyst.