MRI (magnetic resonance imaging) is a way to look inside the body, especially at soft tissue structures such as the nerves, spinal cord, and disc material between the bones of the spine.
In the case of disc material, MRI shows the disc structure, amount of disc herniation, and disc height. Disc degeneration can begin even before it shows up on MRI, but MRI shows early, mild changes. MRI is also useful in showing changes over time.
A small study of 41 adults used MRI to show the spine and discs at the time of injury and again five years later. In all cases, patients had no symptoms at first. Almost half showed significant progression of disc degeneration during the five years. The authors related the disc changes to a lack of sports activity, night shift work, and impaired health in the disc at the start of the study.