Bone Scan:

A bone scan refers to detailed imaging of bone to help identify a region of increased blood flow and metabolic activity or compromise. These studies are sometimes called triple phase bone scan because three readings or measurements of bone metabolic activity are recorded. The bone scan is capable of imaging a large area in contrast to a regional X-ray study.  The bone scan may be performed to rule out an active inflammatory process within or involving bone such as a tumor, infection or fracture.  A short life radioactive compund (technetium 99m MDP) is introduced through an intravenous (IV) line as the initial step of the bone scan procedure.  Within approximately three hours after administration of the chemical, the patient is placed in a special scanner that is capable of detecting the radioactive marker and reveals regions of increased concentration.  

The bone scan is particularly sensitive at detecting disorders associated with regions of altered or increased bone metabolism.  The study can help reveal whether a bone fracture is new (active) or old (chronic).  More recent fractures are generally associated with a region of increased signal on a bone scan due to the greater concentration of radioactive markers at the site of high bone turnover. 

The bone scan is relatively good at identifying the region of involvement but not in discriminating the type of bone involvement such as a specific tumor process.  A positive bone scan may indicate a problem requiring additional testing such as an MRI or CT scan.  The subsequent imaging studies help characterize the nature of lesion for the purpose of implementing a specific plan of diagnostic or therapeutic intervention.