- Bone scan
Bone imaging is a study to visually detect
bone abnormalities. Such imaging studies includemagnetic resonance imaging (MRI), X-raycomputed tomography (CT) and especiallynuclear medicine . In the latter case the patient is injected with a small amount of radioactive material such as 600 MBq oftechnetium-99m -MDP and then scanned with agamma camera , a device sensitive to the radiation emitted by the injected material. In order to view small lesions (less than 1 cm) especially in the spine,single photon emission computed tomography (SPECT) imaging technique may be required. In the United States, most insurance companies require separate authorization for SPECT imaging.About half of the radioactive material is localized by the bones. The more active the
bone turnover , the more radioactive material will be seen. Sometumor s, fractures andinfection s show up as areas of increased uptake. Others can cause decreased uptake of radioactive material. Not all tumors are easily seen on the bone scan. Some lesions, especially lytic (destructive) ones, requirepositron emission tomography (PET) for visualization.About half of the radioactive material leaves the body through the
kidney s and bladder inurine . Anyone having a study should empty their bladder immediately before images are taken.In evaluating for tumors, the patient is injected with the
radioisotope and returns in 2-3 hours for imaging. Image acquisition takes from 30 to 70 minutes, depending if SPECT images are required. If the physician wants to evaluate forosteomyelitis (bone infection) or fractures, then a Three Phase Bone Scan is performed where 20-30 minutes of images (1st and 2nd Phases) are taken during the initial injection. The patient then returns in 2-3 hours for additional images (3rd Phase). Sometimes late images are taken at 24 hours after injection.Pregnant patients should consult with a
physician before consenting to radioactive injections. The total amount of radiation is small, so the bone scan should not be delayed if there is a true medical necessity.References
* [http://www.webmd.com/hw/health_guide_atoz/hw200283.asp Bone scans] from WebMD, accessed
July 9 ,2008 .
* [http://www.skeletalscintigraphy.com SkeletalScintigraphy.com] Information regarding skeletal scintigraphy
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