Present status of CT in the lumbar spine examination.

As the resolution and versatility of CT equipment have improved, the role of CT in the spine has expanded. The purpose of this paper is to review briefly the CT appearance of the normal lumbar root sheaths, the dural sac, and the intervertebral discs, and to illustrate the CT diagnosis of herniated nucleus pulposus, bulging annulus, and diastematomyelia. In herniated discs CT shows a focal protrusion of the disc margin, in a bulging annulus it shows a generalized extension of the disc margin beyond the vertebral body margins. In diastematomyelia CT shows two spinal cords always with dimensions less than that of the normal spinal cord. Replacement of myelography by CT in these conditions and others involving the lumbar spinal canal can be anticipated.