Bone scans are a nuclear medicine (scintigraphic) study that makes use of Technetium 99m (commonly Tc99m-methylene diphosphonate (MDP)) as the active agent.
The study has three phases which follow intravenous injection of the tracer. Sometimes a fourth (delayed/delayed) phase is performed.
- malignancy: detection and follow-up of skeletal metastases
- detection of radiographically occult fractures, e.g. stress or insufficiency fractures
- reflex sympathetic dystrophy
- hip joint prosthesis: evaluation for infection or loosening
- Paget disease
- remove metal objects
- void immediately before study
Tracer dose and route of administration
Tc99m diphosphonate is administered intravenously, at a dose of 20 mCi (740 Mbq) in adults.
Phases (kinetic modelling)
- 2-to-5 second images are obtained for 60 seconds after injection
- demonstrates perfusion
- characterizes blood flow to a particular area
Blood pool phase
- obtained 5 minutes after injection
- demonstrates the blood pool (balance between plasma and interstitium), not the blood flow
- inflammation causes capillary dilatation and increased blood flow
If the study is going to be a triphasic bone scan, a third phase is added.
- obtained 2-4 hours later
- urinary excretion has decreased the amount of the radionuclide in soft tissue
- mechanism of uptake is not known with certainty, although it has been proposed that the radiotracer attaches to hyroxyapatite crystals (chemisorption) 5
- degree of uptake depends on blood flow and rate of new bone formation
- obtained 24 hours after injection as a static image
- 1. Ziessman HA, O'Malley JP, Thrall JH. Nuclear medicine, the requisites in radiology. Mosby. (2006) ISBN:0323029469. Read it at Google Books - Find it at Amazon
- 2. Love C, Din AS, Tomas MB et-al. Radionuclide bone imaging: an illustrative review. Radiographics. 2003;23 (2): 341-58. doi:10.1148/rg.232025103 - Pubmed citation
- 3. Alazraki N, Dries D, Datz F et-al. Value of a 24-hour image (four-phase bone scan) in assessing osteomyelitis in patients with peripheral vascular disease. J. Nucl. Med. 1985;26 (7): 711-7. Pubmed citation
- 4. Toyama H, Kimura Y. [Tracer kinetic modeling in nuclear medicine]. (1993) Kaku igaku. The Japanese journal of nuclear medicine. 30 (12): 1497-501. Pubmed
- 5. McDougall IR. Skeletal scintigraphy. (1979) The Western journal of medicine. 130 (6): 503-14. Pubmed