Lumbar disc disease evaluated by myelography and postmyelography spinal computed tomography.

Five- and ten-millimeter-thick transverse axial computed tomography (CT) scans were obtained at lumbar disc spaces in 81 patients with suspected lumbar disc disease. Scans were obtained following metrizamide myelography. CT and myelography findings were compared and correlated with clinical and surgical findings. Postmyelography CT scan was superior to myelography in 68% since it was able to demonstrate even small herniations. It was especially valuable in the L5-S1 space where the wide epidural space can hide the disc herniation without it being demonstrated by myelography. Also other kinds of pathology which may simulate or complicate disc herniation were readily evaluated by postmyelography CT. Although noncontrast CT scans are usually diagnostic and sufficient, the improved anatomical details obtained by postcontrast CT scans, increase the diagnostic accuracy, and selected, complicated cases may need the CT study with intrathecal metrizamide.