A bone scan is a test used to show trouble spots on the spine. A radioactive chemical, sometimes called a "tracer", is injected into the bloodstream. The chemical quickly attaches itself to areas of the skeleton that are busy making new bone. Several hours after the injection, pictures are taken of the skeleton.
Why is it done?
A bone scan is very useful when it is unclear exactly where the problem is in the skeleton. It offers the ability to take a picture of the entire skeleton and pinpoint any problem areas. Concentrations of the chemical appear as dark spots on the film. In an adult, this usually indicates that there is a problem. The increased bone-making activity is a response to the problem. For example, if there is a fracture of the bone, bone cells will very quickly begin to make new bone to try to repair it. Once these areas are located on the bone scan, the doctor may order additional tests for specific information about your condition.
A bone scan can show problems such as bone tumors, infection, and fractures of the spine. It can also be used to determine bone density and the bone-thinning condition of osteoporosis.
How is it done?
An intravenous line (IV) is started in your hand or arm. The chemical tracer is injected into the bloodstream through the IV. There is a waiting period of two to three hours, while the chemical attaches itself to any areas of bone that are undergoing rapid changes. Usually, you are free to leave and come back after this period.
You will then be asked to lie or sit underneath a large "camera" that takes pictures of your skeleton. Since the chemical tracer is radioactive, it sends out radiation that can be captured by a special camera. The camera is similar to a "Geiger counter" in that it uses film to capture the radioactivity. The procedure takes 30-90 minutes.
What are the limitations?
The bone scan does not show details of the bones or soft tissue. It simply shows how much the bone around a specific area is reacting to the problem.
What are the risks?
There is always the risk of an allergic reaction to anything injected into the bloodstream. In this case, an allergic reaction to the chemical is uncommon. The chemical is radioactive, but it disappears from the body very rapidly-within hours.