Comparison of MR and diskography in detecting radial tears of the anulus: a postmortem study.

Radial tears of the anulus fibrosus, which anatomic studies suggest are a primary event in disk degeneration, can be detected by diskography or MR imaging. We compared the sensitivity of MR and diskography in the detection of anular tears. MR, diskography, and cryomicrotomy anatomic sectioning were performed in eight cadaver lumbar spines. Diskography demonstrated 15 radial tears in 36 intervertebral disks. MR demonstrated 10 of the 15, a sensitivity of 67%. MR (T2-weighted images) in each of the diskographically normal disks showed the high signal intensity characteristic of normal disks. Thirteen of 15 disks from which contrast medium extravasated at diskography had diminished signal intensity in MR images. We conclude that although MR may demonstrate some radial tears of the anulus, and associated changes in the disk, it cannot be used as effectively as diskography to visualize a radial tear.