Intra-articular ganglion cysts of the knee: clinical and MR imaging features

The purpose of this study was to present clinical and MR imaging features o f intra-articular ganglion cysts of the knee. Retrospective review of 1685 consecutive medical records and MR examinations of the knee performed at th ree imaging centers allowed identification of 20 patients (13 men and 7 wom en; mean age 35 years), in whom evidence of intra-articular ganglion cyst w as seen. Of the 20 ganglion cysts, 5 were found in the infrapatellar fat pa d, 10 arose from the posterior cruciate ligament, and 5 from the anterior c ruciate ligament. Three of five patients with ganglion cyst in the infrapat ellar fat pad had a palpable mass. In 7 of 15 patients with ganglion cyst i n the intercondylar notch, exacerbation of pain occurred in a squatting pos ition. On four MR arthrographies, ganglion cysts were an intra-articular ro und, lobulated, low signal intensity lesion. Five cases of fat-suppressed c ontrast-enhanced T1-weighted SE images demonstrated peripheral thin rim enh ancement. The clinical presentation of intraarticular ganglion cyst is vari ed according to its intra-articular location. The MR appearance of intraart icular ganglion cyst is characteristic and usually associated with the cruc iate ligament or the infrapatellar fat pad. Magnetic resonance arthrography has no definite advantage over conventional MR in the evaluation of the le sion. For intraarticular ganglion cyst in the infrapatellar fat pad, fat-su ppressed contrast-enhanced MR imaging could be useful, because a thin, rim- enhancing feature of intra-articular ganglion cyst allows it to be distingu ished from synovial hemangioma and synovial sarcoma.