A bone scan (also known as a Radio Isotopic bone scan) is used to detect areas of bone with an increased blood flow or increased bone turnover. These may be due to inflammation and infection, or fractures, lesions and tumors respectively.
What is a bone scan?
A radioactive tracer which is attracted to bone (especially areas where metabolic rate is high) is injected into the blood stream which passes through the bones and other tissues in the area. As the tracer wears off it gives off radiation which is detected by a camera. A scan may be taken immediately, or after 3-4 hours, or both.
What are bones scans used for?
Bones scans are helpful in diagnosing the following conditions:
- Stress fractures.
- Osteochondral lesions.
- Identify bone tumors or cancers.
- Diagnose bone infections.
- Determine the cause of bone pain when no other cause has been found.
- Diagnose bone conditions such as Paget's disease.
What happens during the test?
You will be asked to remove all jewelry and it is important to tell the radiologist if there is a chance you may be pregnant. Similar to X-rays, radiation could harm an unborn baby.
The injection of the tracer may cause some pain or discomfort, but the actual scan doesn't hurt. The camera may move around the body part and you may be asked to change positions.
Side effects are rare, although some people have reported rashes or swelling in the area or very rarely anaphylactic shock (a severe allergic reaction).
Over the course of several hours, the tracer will be filtered by the kidneys and excreted along with your urine.
The tracer should move evenly throughout the bone, without any denser dark areas. If there are any dense areas (known as hot spots) then this indicates that more tracer has accumulated in that area and that an injury is present. Your results will be compared to other investigations (such as X-rays, MRI scans etc) as well as your symptoms, before a diagnosis is made.