Bone Scan is a study used to detect any inflammatory process in the body. When the source of pain is not clear the bone scan is able to direct the attention of your physician to the area inflammation. The inflammation may be caused by fracture, infection, tumor, or high bone turn over. However, the bone scan will not differentiate between these processes.
When inflammation is present, blood flow to that area increases in proportion to the inflammation. A radioactive marker is injected into a vein (through an IV), and the marker will travel to the area of inflammation. Time is allowed for the marker to reach the area of inflammation or high bone turn over. This takes approximately 3 hours. At that time, a scanner will detect the area in which there is higher level of the marker and results will be printed on specialized paper. The images are obtained in a similar process to a CT Scan or an Xray and the process is usually painless.
Since bone scans can not differentiate between different diagnoses, this test is usually followed by other tests like MRI, or CT scans. Furthermore, not all disease processes will be detected by bone scans. Old fractures are not always seen on bone scans as well as some tumors like Multiple Myeloma, certain thyroid and certain breast cancers.
SPECT scan is a variation of the bone scan and is very sensitive for stress fractures of the spine (Spondylolysis). The SPECT scan is usually ordered for younger adults or teenagers to detect these stress type of fractures in the spine.