RADIOLOGY MCQ---SPINAL CORD EPENDYMOMAS

Q.All are true regarding imaging of spinal cord ependymomas except

a. erosion of the pedicles or of the posterior surface of the vertebral bodies

b. typically heterogeneous on T2-weighted images

c.tend to enhance intensely but irregularly

d.  often have ill defined margin

e.areas of hemorrhage

ANS.---d

Although ependymoma are characteristically quite heterogeneous and astrocytomas are characteristically more homogeneous, it often is very difficult to differentiate these tumors from astrocytomas by imaging criteria. There are a few suggestive criteria, however.

First, ependymomas occur far more often in the lower cord and conus than astrocytomas.

Second, astrocytomas tend to arise eccentrically within the cord, especially posteriorly. Ependymomas arise from ependymal cells in the central canal and tend to be central

 Third, ependymomas are more frequently hemorrhagic than astrocytomas.

 Fourth, regions of low intensity reflecting hypercellularity are more common in ependymomas. Finally, because of the thin pseudocapsule that surrounds ependymomas, it may be possible on very thin sections to identify a plane separating the ependymoma from the cord, unlike astrocytomas, which tend to be infiltrative and have poorly defined borders.