Jonathan Morris MD, Presenter: Nothing to Disclose

Robert James Witte MD, Abstract Co-Author: Nothing to Disclose

John Ignatius Lane MD, Abstract Co-Author: Nothing to Disclose

The radiological literature has suggested that the imaging characteristics of intracranial subependymomas often allow them to be distinguished from the more common ependymomas. The purpose of this study was to determine if the imaging features of pathologically proven ependymal tumors permit this distinction.

A computer-aided search of the medical records at our institution identified all patients with the pathologic diagnosis of subependymoma and ependymoma during the years 1994-2004. We were able to obtain the preoperative MR examinations in seventeen intracranial ependymomas and eleven subependymomas. Studies were retrospectively reviewed. Tumors were characterized according to location (infratentorial vs. supratentorial, intraventricular vs. extraventricular), T1 and T2 signal characteristics, enhancement pattern, and route of spread (ie. cisternal extension, parenchymal invasion).

Seventy five percent of the ependymomas and sixty four percent of the subependymomas were infratentorial. These were primarily located in the fourth ventricle, demonstrated parenchymal invasion in an equal number of cases, and had similar cisternal extension. The remaining five ependymomas were located in the frontal lobe (3), the third ventricle (1), and the atrium of the lateral ventricle (1). The supratentorial subependymomas were all located in the lateral ventricle. When compared to grey matter the solid components of both tumors were primarily hypo to iso intense on T1 weighted images and primarily hyperintense on T2 weighted images. Both tumors had varied enhancement patterns ranging from homogeneous, to heterogeneous, to only minimal enhancement. Fifty percent of both tumors had small cystic components. Hemorrhage was a minor component in both tumors. The age range of the subependymomas was thirty three to eighty one. While the age ranges for ependymomas was one to seventy five.

Significant overlap of MR imaging characteristics was noted between surgically proven intracranial ependymomas and subependymomas. In our experience the neuroradiologist can not reliable distinguish between these histologically distinct tumors based on imaging features alone.

Morris, J, Witte, R, Lane, J, MRI Findings of Intracranial Subependymomas and Ependymomas.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4407646.html