CT features of recurrent lumbar disc herniation.

The CT findings of 29 patients with recurrent lumbar disc herniation, confirmed at reoperation, were analyzed. The shape of the recurrent herniation varied from a shallow bulge to round or triangular mass. Every lesion presented density numbers compatible with disc material. An enhancement study was made in six cases, and the lesions remained non-enhanced. Density measurement on CT proved reliable in the differential diagnosis between recurrent disc herniation and postoperative scar.