Discography or a discogram, is a diagnostic procedure performed to confirm or rule out an intervertebral disc as the source of a person's low back pain or neck pain for that matter. After local anesthetic is applied, a needle injects fluid into the disc between the vertebrae, the resulting pressure may cause pain in a damaged disc. Next, dye is injected into the discs and a special x-ray called a CT scan takes a picture of the disc, identifying the damage in the disc by where the dye leaks to. In a damaged disc, the dye may leak into fissures called annular tears. Discogram results by themselves do not normally determine a surgical decision. A discogram study is another piece of evidence, along with MRI results, x-rays, and clinical findings, that help the surgeon and the patient decide on surgery for back pain.