- contrast medium
Med.a radiopaque substance injected into a part of the body, as the stomach or duodenum, to provide a contrasting background for the tissues in an x-ray or fluoroscopic examination.[1950-55]
* * *Substance comparatively opaque to X rays, which appears lighter on X-ray film and allows a body structure that does not normally contrast with its background to be seen clearly on the film.Common contrast media include barium sulfate and iodized organic compounds. They are given by the route that introduces them into the structure to be examinedswallowed or as an enema for the digestive tract, inhaled for the respiratory tract, or injected for blood vessels and for organs and tissues they supply. Serious reactions to contrast media are not infrequent. See also diagnostic imaging.
* * *▪ medicinesubstance comparatively opaque to X ray, which, when present in an organ or tissue, causes a lighter appearance—i.e., a more definite image—on the X-ray film. Some body structures, such as the lungs, show in X-ray films and in fluoroscopic images by virtue of the sharp difference between the X-ray absorbing power of the air that distends them and that of the pulmonary tissue itself. This difference in absorbing power is called contrast. The heart, being composed largely of muscle and blood, contrasts strongly with the air-filled lungs adjacent to it but scarcely at all with the liver beneath; bones are distinguished from surrounding muscle and the various parts of bone from one another because of the calcium phosphate they contain. To a great extent, however, the clinical usefulness of the X-ray examination depends on the use of artificial contrast media. The most extensively used opaque medium is barium sulfate. Stirred into water and usually flavoured, this insoluble heavy metal salt is swallowed by the patient for examination of his esophagus and stomach; it is also used as a barium enema to examine the rectum, colon, and terminal ileum. Iodized organic compounds are used for examination of the gallbladder, urinary tract, blood vessels, spleen, liver, and bile ducts. X-ray visualization of the bronchi better than that obtained merely by the contrast of contained air is made possible by the introduction into the bronchial tree of unsaturated vegetable oil partially saturated with iodine. An emulsion of ethyl iodophenylundecylate also is used in bronchography and in the examination of the spinal canal (myelography). See also diagnostic imaging.
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См. также в других словарях:
contrast medium — n a substance (as a solution of iodine or suspension of barium sulfate) comparatively opaque to X rays that is introduced into the body (as by injection or swallowing) to contrast an internal part (as the gastrointestinal tract, kidneys, or blood … Medical dictionary
contrast medium — contrast agent a substance administered to enhance the visibility of structures (i.e. increase the contrast) during imaging. In radiography a positive contrast agent (e.g. barium sulphate or a water soluble iodine containing compound) increases… … The new mediacal dictionary
Contrast medium — A medical contrast medium (or contrast agent) is a substance used to enhance the contrast of structures or fluids within the body in medical imaging. It is commonly used to enhance the visibility of blood vessels and the gastrointestinal tract … Wikipedia
contrast medium — noun a substance that is opaque to x rays; when administered it allows a radiologist to examine the organ or tissue it fills • Syn: ↑contrast material • Hypernyms: ↑medium … Useful english dictionary
contrast medium — noun Any substance, such as barium sulfate, used in radiography to increase the visibility of internal structures … Wiktionary
contrast medium — noun Medicine a substance introduced into a part of the body in order to improve the visibility of internal structures during radiography … English new terms dictionary
contrast medium — con′trast me dium n. med a radiopaque substance introduced into a part of the body to provide a contrasting background for the tissues in an x ray examination • Etymology: 1950–55 … From formal English to slang
Вещество Контрастное (Contrast Medium) — любое вещество, применяемое для улучшения видимости структур организма во время проведения рентгенологического обследования. Барий, принимаемый внутрь или вводимый клизмой и позволяющий увидеть на рентгенограмме пищеварительный тракт, является… … Медицинские термины
contrast agent — contrast medium … The new mediacal dictionary
Contrast-enhanced ultrasound — (CEUS) is the application of ultrasound contrast medium to traditional medical sonography. Ultrasound contrast agents rely on the different ways in which sound waves are reflected from interfaces between substances. This may be the surface of a… … Wikipedia