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Scintigraphy

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Scintigraphy

Scintigraphy
Intervention
Scintigraphy
ICD-9-CM 92.0-92.1
MeSH
OPS-301 code 3-70

Scintigraphy ("scint," Latin scintilla, spark) is a form of diagnostic test used in nuclear medicine, wherein radioisotopes are taken internally (via radiopharmaceuticals) and the emitted radiation is captured by external detectors (gamma cameras) to form two-dimensional[1] 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.

Contents

  • By organ or organ system 1
    • Biliary system (Cholescintigraphy) 1.1
    • Lung scintigraphy 1.2
    • Bone 1.3
    • Heart 1.4
    • Parathyroid 1.5
    • Thyroid 1.6
    • Renal and Urinary Systems 1.7
    • Full body 1.8
  • Function tests 2
  • Process 3
  • See also 4
  • References 5
  • External links 6

By organ or organ system

Biliary system (Cholescintigraphy)

Scintigraphy of the

External links

  1. ^ 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
  2. ^ a b c d MedicineNet.com > Definition of Scintigraphy Last Editorial Review: 12/6/2003
  3. ^ Society of Nuclear Medicine Procedure - Guideline for Lung Scintigraphy. Version 3.0, approved February 7, 2004 [2]
  4. ^ George J. Taylor (2004). Primary Care Cardiology. Wiley-Blackwell. p. 100.  
  5. ^ Rosen, Clifford J. (2008-11-18). Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism. John Wiley and Sons. pp. 168–.  
  6. ^ Hindie, Elif; Zanotti-Fregonara, Paolo (2007). "Bone metastases of differentiated thyroid cancer: impact of early 131 I-based detection on outcome" (PDF).  
  7. ^ Scarsbrook AF, Ganeshan A, Statham J, et al. (2007). "Anatomic and functional imaging of metastatic carcinoid tumors". Radiographics 27 (2): 455–77.  

References

See also

Another extensive use of scintillography is in medical imaging techniques which use gamma ray detectors called gamma cameras. Detectors coated with materials which scintillate when subjected to gamma rays are scanned with optical photon detectors and scintillation counters. The subjects are injected with special radionuclides which irradiate in the gamma range inside the region of interest, such as the heart or the brain. A special type of gamma camera is the SPECT (Single Photon Emission Computed Tomography). Another medical scintillography technique, the Positron-emission tomography (PET), which uses the scintillations provoked by electron-positron annihilation phenomena.

Scintillography is mainly used in scintillation cameras in experimental physics. For example, huge neutrino detection underground tanks filled with tetrachloroethylene are surrounded by arrays of photo detectors in order to capture the extremely rare event of a collision between the fluid's atoms and a neutrino.

Cross section of a gamma camera.
Schematic of a photomultiplier tube coupled to a scintillator.

Scintillography is an imaging method of nuclear events provoked by collisions or charged current interactions among nuclear particles or ionizing radiation and atoms which result in a brief, localised pulse of electromagnetic radiation, usually in the visible light range (Cherenkov radiation). This pulse (scintillation) is usually detected and amplified by a photomultiplier or charged coupled device elements, and its resulting electrical waveform is processed by computers to provide two- and three-dimensional images of a subject or region of interest.

Computer representation of false-color image of a cross section of human brain, based on scintillography in Positron-Emission Tomography

Process

Certain tests, such as the Schilling test and Urea breath test, use radioisotopes but are not used to produce a specific image.

Function tests

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[7] such as phaeochromocytomas and neuroblastomas.

Full body

Renal and Urinary Systems

To detect metastases/function of thyroid, the isotopes iodine-131 or technetium-99m is generally used,[6] 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.

Thyroid

Tc99m-sestamibi is used to detect parathyroid adenomas.[5]

Parathyroid

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 of ischemia where arteries are already 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.[4]

Heart

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.

Bone

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.

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.[3]

Lung scintigraphy evaluating lung cancer

Lung scintigraphy

[2] Other scintigraphic tests are done similarly.[2]

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