A bone scan or bone scintigraphy is a bone nuclear medicine imaging technique. It can help diagnose a number of bone conditions, including bone or metastatic cancer, locations of bone and fracture inflammation (which may not be seen in traditional X-ray images), and bone infections.
Nuclear medicine provides functional imaging and allows visualization of bone metabolism or bone remodeling, which most other imaging techniques (such as X-ray computed tomography, CT) can not be performed. Bony scintigraphy competes with positron emission tomography (PET) for imaging of abnormal metabolism in bone, but is much cheaper. Bone scintigraphy has a higher sensitivity but lower specificity than CT or MRI for diagnosis of scaphoid fracture after plain negative radiography.
Video Bone scintigraphy
History
Some of the earliest investigations into bone metabolism were performed by George de Hevesy in the 1930s, using phosphorus-32. In the 1950s and 1960s calcium-45 was investigated, but as a beta emitter proved difficult to image. Positron imaging and gamma emitters such as fluorine-18 and strontium isotopes with rectilinear scanners are more useful. The use of technetium-99m ( 99m Tc) labeled phosphate, diphosphonates or the same agent, as in modern techniques, was first proposed in 1971.
Maps Bone scintigraphy
Principles
The most common radiopaophonic for bone skintigraphy is 99m Tc with methylene diphosphonate (MDP). MDP absorbs into bone mineral crystalline hydroxyapatite. Mineralization occurs in osteoblasts, representing sites of bone growth, where MDP (and other diphosphates) "bind to the hydroxyapatite crystals in the proportion of local blood flow and osteoblastic activity and hence the markers of bone turnover and bone perfusion".
The more active the bone turnover, the more radioactive material you will see. Some tumors, fractures and infections appear as areas of increased uptake.
Technique
In a typical bone scanning technique, the patient is injected (usually into a vein in the arm or hand, occasionally leg) with up to 740 MBq technetium-99m-MDP and then scanned with a gamma camera, which captures anterior planar and posterior photon emission tomography images or single photon (SPECT). To see small lesions, SPECT imaging techniques may be preferred over planar scintigraphy.
In a single-phase protocol (skeletal imaging only), which will primarily highlight osteoblasts, images are usually obtained 2-5 hours after injection (after four hours 50-60% of activity will be repaired into bone). Two or three phase protocols use additional scans at different points after the injection to obtain additional diagnostic information. A dynamic (ie multiple frames obtained) learns immediately after the injection captures the perfusion information. A second phase "blood pool" image following perfusion (if performed in a three-phase technique) can help diagnose inflammatory conditions or blood supply problems.
Dosis efektif yang khas diperoleh selama scan tulang adalah 6,3 millisieverts (mSv).
Referensi
Tautan eksternal
- "Pemindaian tulang". WebMD . Diperoleh 9 Juli, 2008 .
Source of the article : Wikipedia
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