Computed tomography and magnetic resonance imaging of intracranial ependymomas.

We evaluated the neuroimages of 18 pathologically proven cases of ependymoma, 15 cases by CT evaluation and 9 cases by MRI evaluations. In 7 cases of supratentorial ependymomas, 4 were intraparenchymal and 3 were intraventricular ependymomas originating from the ependymal lining layer, the floor of the lateral ventricle, which was best demonstrated on a sagittal MR image. For the cases of infratentorial ependymomas, all were intraventricular. Evidence of seeding through the cerebrospinal fluid pathway to the basal cisterns, spinal cord or ventricles was presented in 6 cases which were particularly well demonstrated in the sagittal section with gadolinium-DTPA enhanced MR imaging. On CT scan, isodense tumors with various portions of high enhancement within a moderate enhancement mass were the most frequent features. In MRI, isointensity relative to gray matter on T1-weighted images and hyperintensity on mild and heavy T2-weighted images were most frequently seen. The signal heterogeneity representing soft tissue, small cysts, necrosis, calcification, vessels or hemosiderin was better visualized in MRI which offered a better assessment of the character of tumor compositions. The soft tissue mass, calcification and cysts as revealed in both CT and MRI are nonspecific, but the location, ages, CSF seeding and particularly, superior MR images can offer very important clues for the diagnosis of ependymoma.