A myelogram is a diagnostic imaging test generally done by a radiologist. It uses a contrast dye and X-rays or computed tomography (CT) to look for problems in the spinal canal. Problems can develop in the spinal cord, nerve roots, and other tissues. This test is also called myelography. The contrast dye is injected into the spinal column before the procedure. The contrast dye appears on an X-ray screen allowing the radiologist to see the spinal cord, subarachnoid space, and other nearby structures more clearly than with standard X-rays of the spine. The radiologist will also use a CT scan when doing a myelogram. A CT or CAT scan is an imaging test that uses X-rays and a computer to make detailed images of the body. A CT scan shows details images of the spinal canal. CT scans show more details than standard X-rays.