A bone scan is a nuclear scanning test that identifies new areas of bone growth or breakdown. It can be done to evaluate damage to the bones, find cancer that has spread (metastasized) to the bones, and monitor conditions that can affect the bones (including infection and trauma). A bone scan can often find a problem days to months earlier than a regular X-ray test.
For a bone scan, a radioactive tracer substance is injected into a vein in the arm. The tracer then travels through the bloodstream and into the bones. This process may take several hours. A special camera (gamma) takes pictures of the tracer in the bones. This helps show cell activity and function in the bones. Areas that absorb little or no amount of tracer appear as dark or "cold" spots, which may indicate a lack of blood supply to the bone (bone infarction) or the presence of certain types of cancer. Areas of rapid bone growth or repair absorb increased amounts of the tracer and show up as bright or "hot" spots in the pictures. Hot spots may indicate problems such as arthritis, the presence of a tumor, a fracture, or an infection.
A bone scan may be done on the entire body or just a part of it.