A discography is an examination of a disc by means of a contrast agent. It should not be confused with a myelography since during myelography, a contrast agent is injected into the space around the spinal cord.
In case of discography, the contrast agent is injected into the disc through a very small needle. This is done sterilely under CT- or X-ray-guidance in an operating room. Besides the application of a contrast agent and the analysis of the images, there is a pressure test with a special manometer, which measures if a disc is abnormally sensitive to pain. According to this information, physicians can find the disc, which is pathologically degenerated.
The upper X-ray image shows a discography of a disc herniation with a leakage of a contrast agent into the spinal canal (lower disc). Through fine needles is the contrast agent injected, visible as a dark/black fluid. The lower CT image shows a recontructed spine for the better evaluation of even small tears of a vertebral disc. The contrast agent is visible as a bright/white liquid.
A discography is indicated if a tear in a disc is expected, which could not be proven by an MRI examination.