any internally administered substance that has a different opacity from soft tissue on radiography or computed tomography; includes barium, used to opacify parts of the gastrointestinal tract; water-soluble iodinated compounds, used to opacify blood vessels or the genitourinary tract; may refer to air occurring naturally or introduced into the body; also, paramagnetic substances used in magnetic resonance imaging. Synonym(s): contrast agent, contrast material
See contrast medium.
See contrast medium. See contrast medium.
Also called a contrast medium, this is usually a barium or iodine dye that is injected into the area under investigation. The dye makes the interior body parts more visible on an x-ray film.