Bone scintigraphy is a technique in nuclear medicine to image bones. It is generally used for conditions that may not be picked up during other types of imaging studies because of the density of the bone, such as cancer, inflammation and even fractures that don't show up on an x-ray. It also allows imaging of bone metabolism. Although it does not provide much more detail than a PET scan, it is considerably less expensive.
The patient is prepared by injecting them with a solution that contains an isotope of technetium. Two to five hours latter, they are then scanned with a camera that picks up gamma rays. If a comparison is needed, they will be scanned again a few hours later.
The technetium binds to sites where bone is actually growing, so it prefers sites where there is cancerous growth, inflammation, and breaks that are healing, which show up brighter on the scan.