A myelogram uses fluoroscopy and a special dye called contrast material to make pictures of the bones and the fluid-filled space (subarachnoid space) between the bones in your spine (spinal canal). A myelogram may be done to find a tumor, an infection, problems with the spine such as a herniated disc, or narrowing of the spinal canal caused by arthritis.

During the test, a contrast material is put injected into the subarachnoid space with a thin needle. The contrast material moves through the space so the nerve roots and spinal cord can be seen more clearly. Fluoroscopy images are taken before and after the contrast material is injected. A CT scan is done immediately after, while the contrast material is still in your body for further diagnostic results.