MR imaging in chronic partial epilepsy: role of contrast enhancement

Gadopentetate dimeglumine was administered prospectively to 150 consecutive patients who had had partial epilepsy for longer than 1 year to determine whether it is routinely indicated for the diagnosis of this disorder. MR abnormalities correlating with clinical or electroencephalographically documented seizure foci were detected in 69 cases (46%). Contrast enhancement was seen in 33 of these lesions, but the presence of enhancement altered the original radiologic diagnosis in only 17 (11%) of 150 cases. In only two cases (1%) did contrast administration reveal lesions that were not definitely apparent on the unenhanced images. The utility of contrast administration could not be predicted on the basis of seizure type (simple or complex) or the presence of secondary generalization. Gadopentetate dimeglumine does not appear to be routinely required in the MR workup of patients with chronic partial epilepsy. It should be used selectively to clarify or better define the nature of abnormalities encountered on unenhanced images.