Contrast enhancement in CT differentiation between recurrent disk herniation and postoperative scar: prospective study.

Recurrent disk herniation and postoperative scarring are among the major causes of recurrent symptoms after surgery for lumbar disk disease. The myelographic differentiation between these two etiologies is, at best, difficult. To evaluate the role of intravenous contrast enhancement and its impact on making this differentiation using computed tomography (CT), 98 postoperative symptomatic patients were studied prospectively with this technique. Twenty-two patients had subsequent reexploration (23 disk spaces). The unenhanced and enhanced studies of these patients were interpreted independently without surgical information. With contrast enhancement, only three CT studies were considered indeterminate, whereas 10 studies without contrast enhancement were indeterminate. The overall correct diagnosis with contrast enhancement was 17 (74%) of 23, while only 43% of the unenhanced studies yielded the correct diagnosis. Therefore, intravenous contrast enhancement significantly increased the diagnostic accuracy and level of confidence in making the differentiation between recurrent herniated disk and scar.