MRI Characteristics of Spinal Ependymoma in WHO Grade II: A Review of 59 Cases.

Abstract

Retrospective multicenter study. The goal of this study is to determine the characteristic imaging features of spinal ependymoma in a review of magnetic resonance imaging (MRI) data for a large series of surgically proven cases. Common spinal intramedullary neoplasms are mostly ependymomas and comprise 50% to 60% of spinal neuroepithelial tumors in adults. Preoperative prediction of the pathological diagnosis could enhance surgical planning and explanation of the procedure to patients. However, these types of tumors exhibit a variety of MRI findings. Records were examined for 59 patients who underwent surgery for spinal cord ependymoma and had a pathological diagnosis of cellular ependymoma of World Health Organization classification grade II. The ependymomas included 28 in the cervical spine, 34 in the thoracic spine, and 3 conus lesions. All cases were isointense or hypointense on T1-weighted MRI, and 55 (93%) were hyperintense on T2-weighted MRI. Tumors were located centrally in all cases; 50 (85%) showed surrounding cord edema; and 52 (88%) had associated cysts, including 36 (61%) rostral or caudal cysts, 10 (17%) intratumoral cysts, and 6 (10%) with syringomyelia. Of the 59 tumors, 17 (29%) showed the "cap sign," a rim of extreme hypointensity seen around the tumor on T2-weighted images, due to hemosiderin. In gadolinium-enhanced MRI, all cases were enhanced, and 27 (46%), 16 (27%), 11 (19%), and 5 (8%) cases showed homogeneous, heterogeneous, rim, and nodular enhancement, respectively. Hypointense changes on T2-weighted MRI and hemosiderin deposition reflect easy bleeding. Tumors are associated with various types of cysts, and gadolinium-enhancement patterns reflect a variety of intratumor cellular components. In cases in which the whole tumor shows gadolinium enhancement on MRI, rostral, or caudal cyst and a cap sign with hemorrhage are characteristics of grade II classical ependymoma. 3.