It is a computed tomography (CT) scan of the lower spine and surrounding tissues with a contrast agent. The scan is performed to evaluate fractures, ruptured disks and any other abnormality of the spine, such as those due to arthritis or deformities. An abnormal result may reveal the following conditions: cyst, herniated disk, cancer that has spread to the spine, osteoarthritis, osteomalacia (softening of the bones) and pinched nerve.