Radiological features of subependymoma with emphasis on computed tomography

The features of 17 symptomatic subependymomas on X-ray computed tomography are described. Thirteen were reviewed from isolated case reports and 4 were original material. Over half were entirely intraventricular, 6 extended into brain substance and 2 into subarachnoidal cisterns. Twelve were isodense, 15 showed diffuse but irregular enhancement, and 5 contained nodular calcification. Large low density cysts, intratumoural haemorrhage and brain oedema were found almost exclusively in lesions extending into brain substance. It is concluded that subependymomas resemble ependymomas too closely on CT to be distinguished radiographically from them as a separate group. However subependymomas contain calcification slightly less frequently, and usually appear as mainly intraventricular lesions even when they occur above the tentorium.