Comparison of high-resolution computed tomography with discography in the evaluation of lumbar disc herniations

After failure of conservative treatment, 100 patients with symptoms suggestive of lumbar herniated nucleus pulposus (HNP) but without objective deficits were investigated both by high-resolution CT (without intravenous or intrathecal contrast) and by discography. The L4-L5 and L5-S1 discs were investigated by both techniques in all patients. In addition, the L3-L4 disc was investigated in 20 patients. The 220 investigated discs were sorted out into 6 CT categories according to morphologic and technical criteria. They were also classified into 3 discographic groups according to morphologic and clinical criteria. Based on morphologic considerations alone, the false-negative CT rates varied from 0 to 64% and the false-positive rates varied from 0 to 19%, depending on the category under consideration. Based on both morphologic and clinical consideration, the false-negative CT rates varied from 34 to 57% and the false-positive CT rates varied from 23 to 50%. Thus, high-resolution CT does not constitute an adequate means of investigation for this category of patients and discography appears justified before considering any form of radical therapy.