Scintigraphy ("scint," Latin scintilla, spark) is a form of diagnostic test used in nuclear medicine, wherein radioisotopes (here called radiopharmaceuticals) are taken internally, and the emitted radiation is captured by external detectors (gamma cameras) to form two-dimensional images. In contrast, SPECT and positron emission tomography (PET) form 3-dimensional images, and are therefore classified as separate techniques to scintigraphy, although they also use gamma cameras to detect internal radiation. Scintigraphy is unlike a diagnostic X-ray where external radiation is passed through the body to form an image.
By organ or organ system 
Biliary system (Cholescintigraphy) 
Scintigraphy of the biliary system is called cholescintigraphy and is done to diagnose obstruction of the bile ducts by a gallstone (cholelithiasis), a tumor, or another cause. It can also diagnose gallbladder diseases, e.g. bile leaks of biliary fistulas. In cholescintigraphy, the injected radioactive chemical is taken up by the liver and secreted into the bile. The radiopharmaceutical then goes into the bile ducts, the gallbladder, and the intestines. The gamma camera is placed on the abdomen to picture these perfused organs. Other scintigraphic tests are done similarly.
Lung scintigraphy 
The most common indication for lung scintigraphy is to diagnose pulmonary embolism, e.g. with a ventilation/perfusion scan. Less common indications include evaluation of lung transplantation, preoperative evaluation, evaluation of right-to-left shunts.
In the ventilation phase of a ventilation/perfusion scan, a gaseous radionuclide xenon or technetium DTPA in an aerosol form (or ideally using Technegas, a radioaerosol invented in Australia by Dr Bill Burch and Dr Richard Fawdry) is inhaled by the patient through a mouthpiece or mask that covers the nose and mouth. The perfusion phase of the test involves the intravenous injection of radioactive technetium macro aggregated albumin (Tc99m-MAA). A gamma camera acquires the images for both phases of the study.
For example, the ligand methylene-diphosphonate (MDP) can be preferentially taken up by bone. By chemically attaching technetium-99m to MDP, radioactivity can be transported and attached to bone via the hydroxyapatite for imaging. Any increased physiological function, such as a fracture in the bone, will usually mean increased concentration of the tracer.
A thallium stress test is a form of scintigraphy, where the amount of thallium-201 detected in cardiac tissues correlates with tissue blood supply. Viable cardiac cells have normal Na+/K+ ion exchange pumps. Thallium binds the K+ pumps and is transported into the cells. Exercise or dipyridamole induces widening (vasodilation) of normal coronary arteries. This produces coronary steal from areas where arteries are maximally dilated. Areas of infarct or ischemic tissue will remain "cold". Pre- and post-stress thallium may indicate areas that will benefit from myocardial revascularization. Redistribution indicates the existence of coronary steal and the presence of ischemic coronary artery disease.
To detect metastases/function of thyroid, the isotopes iodine-131 or Technetium-99m is generally used, and for this purpose the iodide isotope does not need to be attached to another protein or molecule, because thyroid tissue takes up free iodide actively.
Full body 
Examples are gallium scans, indium white blood cell scans, Iobenguane scan (MIBG) and octreotide scans. The MIBG scan detects adrenergic tissue and thus can be used to identify the location of tumors such as phaeochromocytomas and neuroblastomas.
Function tests 
See also 
- thefreedictionary.com > scintigraphy Citing: Dorland's Medical Dictionary for Health Consumers, 2007 by Saunders; Saunders Comprehensive Veterinary Dictionary, 3 ed. 2007; McGraw-Hill Concise Dictionary of Modern Medicine, 2002 by The McGraw-Hill Companies
- MedicineNet.com > Definition of Scintigraphy Last Editorial Review: 12/6/2003
- Society of Nuclear Medicine Procedure - Guideline for Lung Scintigraphy. Version 3.0, approved February 7, 2004 
- George J. Taylor (2004). Primary Care Cardiology. Wiley-Blackwell. p. 100. ISBN 1-4051-0386-8.
- Rosen, Clifford J. (2008-11-18). Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism. John Wiley and Sons. pp. 168–. ISBN 978-0-9778882-1-4. Retrieved 17 July 2011.
- Hindie, E.; Zanotti-Fregonara, P.; Keller, I.; Duron, F.; Devaux, J. -Y.; Calzada-Nocaudie, M.; Sarfati, E.; Moretti, J. -L. et al. (2007). "Bone metastases of differentiated thyroid cancer: Impact of early 131I-based detection on outcome". Endocrine Related Cancer 14 (3): 799–807. doi:10.1677/ERC-07-0120. PMID 17914109. 
- Scarsbrook AF, Ganeshan A, Statham J, et al. (2007). "Anatomic and functional imaging of metastatic carcinoid tumors". Radiographics 27 (2): 455–77. doi:10.1148/rg.272065058. PMID 17374863.
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