A myelogram uses X-rays (fluoroscopy) and a special dye called contrast material to make pictures of bones and nerves of the spine (spinal canal).
The spinal canal contains the spinal cord and nerve roots surrounded by a fluid-filled space called the subarachnoid space. For a myelogram, the dye (which contains iodine) is put into the subarachnoid space. X-ray pictures are taken as the dye moves into different areas of the subarachnoid space.
A myelogram can be used to find:
A blockage in the spinal canal that may be caused by a tumor or by a spinal disc that has ruptured (herniated).
Inflammation of the membrane (arachnoid membrane) that covers the brain and spinal cord.
Problems of the blood supply to the spinal cord.
Problems of the spinal cord and the nerves that branch off from the spinal cord.