Image 1

Clinical History: 
Back pain in a 58 year old woman

Diagnosis:
Synovial cyst

MR Technique: 
2D FSE T1- and T2-weighted axial scans obtained at 3 T on a Siemens Verio MR unit are presented. The slice thickness was 4 mm, with TR/TE = 700/9.3 and 3000/94 and scan times of 3:20 and 2:18 respectively.

Imaging Findings:
At the L5-S1 level, there is a round, 2 x 1 cm cystic lesion, slightly hyperintense to CSF on the T1-weighted scan and isointense to CSF on the T2-weighted scan, adjacent to the medial border of left L5-S1 facet joint. The lesion displays mass effect, with displacement and compression of both S1 and S2 on the left. Synovial cysts can have any signal intensity on T1- and T2-weighted scans, depending upon the fluid contents, and can mimic the clinical symptoms of a disk herniation