The value of MRI and CT-discography as a basis for surgical decision making

It is important to know the presence/absence of perforation of the posterior longitudinal ligament by herniation before surgery of lumbar disc herniation. MR images and CTD (CT-discography) findings of 25 patients with lumbar disc herniation and the findings at surgery were compared, and the possibility of judging presence/absence of perforation of posterior longitudinal ligament by herniation was retrospectively studied. The cases showing broken black line on MRI and the cases with epidural leak on CT were diagnosed as having perforation of the posterior longitudinal ligament. The diagnosis was made by a radiologist to whom the clinical symptoms of the patients had not been informed, and compared with the findings at surgery. The accuracy was 64.0%, sensitivity 69.2%, and specificity 58.3% on MRI, as for CTD on the other hand, accuracy was 60.0%, sensitivity 54.6%, and specificity 54.6%. The usefulness of black line on MRI and epidural leak on CTD for preoperative diagnosis of the presence/absence of perforation of the posterior longitudinal ligament by herniation was low. (S.Y.)