Scintigraphy

Last updated
Scintigraphy
Scyntygrafia.JPG
Scintigraphy
ICD-9-CM 92.0-92.1
MeSH D011877
OPS-301 code 3-70

Scintigraphy (from Latin scintilla, "spark"), also known as a gamma scan, is a diagnostic test in nuclear medicine, where radioisotopes attached to drugs that travel to a specific organ or tissue (radiopharmaceuticals) are taken internally and the emitted gamma radiation is captured by gamma cameras, which are external detectors that form two-dimensional images [1] in a process similar to the capture of x-ray images. In contrast, SPECT and positron emission tomography (PET) form 3-dimensional images and are therefore classified as separate techniques from 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

Process

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

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 charge-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.

Schematic of a photomultiplier tube coupled to a scintillator. Photomultipliertube.svg
Schematic of a photomultiplier tube coupled to a scintillator.
Cross section of a gamma camera. Gamma camera cross section.PNG
Cross section of a gamma camera.

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.

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.

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. [2] It can also diagnose gallbladder diseases, e.g. bile leaks of biliary fistulas. [2] 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. [2] Other scintigraphic tests are done similarly. [2]

Lung scintigraphy

Lung scintigraphy evaluating lung cancer Lung scintigraphy keosys.JPG
Lung scintigraphy evaluating lung cancer

The most common indication for lung scintigraphy is to diagnose pulmonary embolism, e.g. with a ventilation/perfusion scan and may be appropriate for excluding PE in pregnancy. [3] Less common indications include evaluation of lung transplantation, preoperative evaluation, evaluation of right-to-left shunts. [4]

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.

Bone

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.

Heart

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. [5]

Parathyroid

Tc99m-sestamibi is used to detect parathyroid adenomas. [6]

Thyroid

To detect metastases/function of thyroid, the isotopes technetium-99m or iodine-123 are generally used, [7] [8] 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.

Renal and urinary systems

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 [9] such as pheochromocytomas and neuroblastomas.

Function tests

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

History

Scintigraphic scanning was invented and proven by Neurologist and Radiologist professor Bernard George Ziedses des Plantes. [10] He presented the results in 1950 under the name 'indirect Autoradiograph’. In 1970, the Physikalisch-Medizinische Gesellschaft für Neuroradiologie (The Physics and Medical Society for Neuroradiology) instituted the ‘Ziedses des Plantes Medal'. It was first awarded to W. Oldendorf en G. Hounsfield in 1974 for Computer Tomography (CT). Later, in 1985, the medal was awarded to Ziedses des Plantes himself. In 1977 he received The Roentgen Medal. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Positron emission tomography</span> Medical imaging technique

Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging purposes, depending on the target process within the body.

<span class="mw-page-title-main">Radiology</span> Branch of medicine

Radiology is the medical specialty that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography, but today it includes all imaging modalities, including those that use no ionizing electromagnetic radiation, as well as others that do, such as computed tomography (CT), fluoroscopy, and nuclear medicine including positron emission tomography (PET). Interventional radiology is the performance of usually minimally invasive medical procedures with the guidance of imaging technologies such as those mentioned above.

<span class="mw-page-title-main">Medical imaging</span> Technique and process of creating visual representations of the interior of a body

Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to reveal internal structures hidden by the skin and bones, as well as to diagnose and treat disease. Medical imaging also establishes a database of normal anatomy and physiology to make it possible to identify abnormalities. Although imaging of removed organs and tissues can be performed for medical reasons, such procedures are usually considered part of pathology instead of medical imaging.

<span class="mw-page-title-main">Single-photon emission computed tomography</span> Nuclear medicine tomographic imaging technique

Single-photon emission computed tomography is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera, but is able to provide true 3D information. This information is typically presented as cross-sectional slices through the patient, but can be freely reformatted or manipulated as required.

<span class="mw-page-title-main">Nuclear medicine</span> Medical specialty

Nuclear medicine, or nucleology, is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease. Nuclear imaging is, in a sense, radiology done inside out, because it records radiation emitted from within the body rather than radiation that is transmitted through the body from external sources like X-ray generators. In addition, nuclear medicine scans differ from radiology, as the emphasis is not on imaging anatomy, but on the function. For such reason, it is called a physiological imaging modality. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) scans are the two most common imaging modalities in nuclear medicine.

A radioactive tracer, radiotracer, or radioactive label is a synthetic derivative of a natural compound in which one or more atoms have been replaced by a radionuclide. By virtue of its radioactive decay, it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products. Radiolabeling or radiotracing is thus the radioactive form of isotopic labeling. In biological contexts, experiments that use radioisotope tracers are sometimes called radioisotope feeding experiments.

<span class="mw-page-title-main">Gamma camera</span> Camera to record gamma radiation

A gamma camera (γ-camera), also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body or the distribution of medically injected, inhaled, or ingested radionuclides emitting gamma rays.

Technetium (<sup>99m</sup>Tc) sestamibi Pharmaceutical drug

Technetium (99mTc) sestamibi (INN) is a pharmaceutical agent used in nuclear medicine imaging. The drug is a coordination complex consisting of the radioisotope technetium-99m bound to six (sesta=6) methoxyisobutylisonitrile (MIBI) ligands. The anion is not defined. The generic drug became available late September 2008. A scan of a patient using MIBI is commonly known as a "MIBI scan".

<span class="mw-page-title-main">Isotopes of iodine</span> Nuclides with atomic number of 53 but with different mass numbers

There are 40 known isotopes of iodine (53I) from 108I to 147I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element.

<span class="mw-page-title-main">Bone scintigraphy</span> Nuclear medicine imaging technique

A bone scan or bone scintigraphy is a nuclear medicine imaging technique of the bone. It can help diagnose a number of bone conditions, including cancer of the bone or metastasis, location of bone inflammation and fractures, and bone infection (osteomyelitis).

A gallium scan is a type of nuclear medicine test that uses either a gallium-67 (67Ga) or gallium-68 (68Ga) radiopharmaceutical to obtain images of a specific type of tissue, or disease state of tissue. Gallium salts like gallium citrate and gallium nitrate may be used. The form of salt is not important, since it is the freely dissolved gallium ion Ga3+ which is active. Both 67Ga and 68Ga salts have similar uptake mechanisms. Gallium can also be used in other forms, for example 68Ga-PSMA is used for cancer imaging. The gamma emission of gallium-67 is imaged by a gamma camera, while the positron emission of gallium-68 is imaged by positron emission tomography (PET).

Iodine-123 (123I) is a radioactive isotope of iodine used in nuclear medicine imaging, including single-photon emission computed tomography (SPECT) or SPECT/CT exams. The isotope's half-life is 13.2232 hours; the decay by electron capture to tellurium-123 emits gamma radiation with a predominant energy of 159 keV. In medical applications, the radiation is detected by a gamma camera. The isotope is typically applied as iodide-123, the anionic form.

<span class="mw-page-title-main">Ventilation/perfusion scan</span> Medical imaging to evaluate circulation of air and blood in the lungs

A ventilation/perfusion lung scan, also called a V/Q lung scan, or ventilation/perfusion scintigraphy, is a type of medical imaging using scintigraphy and medical isotopes to evaluate the circulation of air and blood within a patient's lungs, in order to determine the ventilation/perfusion ratio. The ventilation part of the test looks at the ability of air to reach all parts of the lungs, while the perfusion part evaluates how well blood circulates within the lungs. As Q in physiology is the letter used to describe bloodflow the term V/Q scan emerged.

<span class="mw-page-title-main">Technetium-99m</span> Metastable nuclear isomer of technetium-99

Technetium-99m (99mTc) is a metastable nuclear isomer of technetium-99, symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical radioisotope in the world.

<span class="mw-page-title-main">Myocardial perfusion imaging</span> Nuclear medicine imaging method

Myocardial perfusion imaging or scanning is a nuclear medicine procedure that illustrates the function of the heart muscle (myocardium).

<span class="mw-page-title-main">Iobenguane</span> Chemical compound

Iobenguane, or MIBG, is an aralkylguanidine analog of the adrenergic neurotransmitter norepinephrine (noradrenaline), typically used as a radiopharmaceutical. It acts as a blocking agent for adrenergic neurons. When radiolabeled, it can be used in nuclear medicinal diagnostic and therapy techniques as well as in neuroendocrine chemotherapy treatments.

Perfusion is the passage of fluid through the lymphatic system or blood vessels to an organ or a tissue. The practice of perfusion scanning is the process by which this perfusion can be observed, recorded and quantified. The term perfusion scanning encompasses a wide range of medical imaging modalities.

Nuclear medicine physicians, also called nuclear radiologists or simply nucleologists, are medical specialists that use tracers, usually radiopharmaceuticals, for diagnosis and therapy. Nuclear medicine procedures are the major clinical applications of molecular imaging and molecular therapy. In the United States, nuclear medicine physicians are certified by the American Board of Nuclear Medicine and the American Osteopathic Board of Nuclear Medicine.

Technetium (<sup>99m</sup>Tc) tetrofosmin Chemical compound

Technetium (99mTc) tetrofosmin is a drug used in nuclear medicine cardiac imaging. It is sold under the brand name Myoview. The radioisotope, technetium-99m, is chelated by two 1,2-bis[di-(2-ethoxyethyl)phosphino]ethane ligands which belong to the group of diphosphines and which are referred to as tetrofosmin.

<span class="mw-page-title-main">Radiopharmaceutical</span> Pharmaceutical drug which emits radiation, used as a diagnostic or therapeutic agent

Radiopharmaceuticals, or medicinal radiocompounds, are a group of pharmaceutical drugs containing radioactive isotopes. Radiopharmaceuticals can be used as diagnostic and therapeutic agents. Radiopharmaceuticals emit radiation themselves, which is different from contrast media which absorb or alter external electromagnetism or ultrasound. Radiopharmacology is the branch of pharmacology that specializes in these agents.

References

  1. ↑ "Scintigraphy". Dorland's Medical Dictionary for Health Consumers; Saunders; Saunders Comprehensive Veterinary Dictionary (3rd ed.). McGraw-Hill Concise Dictionary of Modern Medicine. 2007.
  2. 1 2 3 4 "Definition of Scintigraphy". MedicineNet.com. 6 December 2003.
  3. ↑ van Mens TE, Scheres LJ, de Jong PG, Leeflang MM, Nijkeuter M, Middeldorp S (January 2017). Cochrane Vascular Group (ed.). "Imaging for the exclusion of pulmonary embolism in pregnancy". The Cochrane Database of Systematic Reviews. 1 (1): CD011053. doi:10.1002/14651858.CD011053.pub2. PMC   6464730 . PMID   28124411.
  4. ↑ "Guideline for Lung Scintigraphy" (PDF) (3.0 ed.). Society of Nuclear Medicine Procedure. 7 February 2004. Archived from the original (PDF) on 23 July 2011. Retrieved 2 April 2010.
  5. ↑ Taylor GJ (2004). Primary Care Cardiology. Wiley-Blackwell. p. 100. ISBN   1-4051-0386-8.
  6. ↑ Rosen CJ (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.
  7. ↑ Hindié E, Zanotti-Fregonara P, Keller I, Duron F, Devaux JY, Calzada-Nocaudie M, et al. (September 2007). "Bone metastases of differentiated thyroid cancer: impact of early 131I-based detection on outcome". Endocrine-Related Cancer. 14 (3). Bioscientifica: 799–807. doi: 10.1677/ERC-07-0120 . PMID   17914109.
  8. ↑ Mandel SJ, Shankar LK, Benard F, Yamamoto A, Alavi A (January 2001). "Superiority of iodine-123 compared with iodine-131 scanning for thyroid remnants in patients with differentiated thyroid cancer". Clinical Nuclear Medicine. 26 (1): 6–9. doi: 10.1097/00003072-200101000-00002 . PMID   11139058. S2CID   44740573.
  9. ↑ Scarsbrook AF, Ganeshan A, Statham J, Thakker RV, Weaver A, Talbot D, et al. (2007). "Anatomic and functional imaging of metastatic carcinoid tumors". Radiographics. 27 (2): 455–77. doi:10.1148/rg.272065058. PMID   17374863.
  10. ↑ Valk, Jaap (June 1994). "Bernard George Ziedses des Plantes, MD". Radiology. 191 (3): 876. doi:10.1148/radiology.191.3.876-b.
  11. ↑ Busch, Dr. Uwe (1977). "The Roentgen Medal 1970-1979". Deutsches Röntgen Museum. Retrieved August 7, 2022.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.