A discogram uses x-ray and a special dye injected into the center of the injured disc(s). The dye makes the disc clearly visible on x-ray film and a fluoroscope screen. The discogram can help your doctor diagnose which disc(s) are damaged and whether you will need surgery. The discogram is better than an x-ray or myelogram for determining whether there is a disc problem, because a plain x-ray shows only the vertebrae, and a myelogram only shows whether the disc has entered the spinal canal.