MRI of Ganglion Cysts in Uncommon Sites or with Atypical Appeara

loskeletal system has become a well recognized and useful diagnostic method, especially for soft tissue lesions, and its use has been increasing. Ganglion cysts are common lesions which can be easily diagnosed in a clinician office, and in most cases do not, therefore, require further sophisticated and costly evaluation. They can be identified incidentally during the evaluation of MR images obtained during the investigation of other disorders, though some unusual ganglions can be confused with other more serious lesions. The typical MR imaging finding of a ganglion cyst is a well defined, relatively small, round-to-ovoid mass of intermediate signal intensity, as seen on T1-weighted images, and of homogeneous high signal intensity, as seen on T2-weighted images, with non-enhancement or thin rim enhancement. The isointensity seen on T1weighted images can be explained by the high protein content (1). The correct diagnosis of the ganglion cysts which develop at classical sites and show typical MR features is straightforward, but cysts either with unusual imaging characteristics or at uncommon sites often cause some diagnostic confusion. Most ganglion cysts, even though located at uncommon sites, usually demonstrate typical MR imaging features, namely a well-marginated cystic mass which is isointense and shows homogeneously high signal intensity on T1and T2-weighted images, respectively. In addition, ganglion cysts arising at several specific sites, such as the cruciate ligament, meniscus, shoulder notches, or labrum possess certain characteristic imaging findings which are also a great help in diagnosis. Complicated or long-standing ganglion cysts can become quite large and multiseptated with a thick wall, or J Korean Radiol Soc 1999;41:3 93-3 9 9