A substance opaque to X-rays, introduced into hollow or fluid-filled body parts to show them up on X-ray film. Barium is one of the most commonly used contrast media (see barium X-ray examinations).
A material that is used to increase the visibility of the body’s tissues and organs during RADIOGRAPHY. A common example is the use of barium which is given by mouth or as an enema to show up the alimentary tract.
(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 density of a structure. Gas is a negative contrast agent. Positive and negative contrast media can be used together (e.g. barium sulphate and gas in a double-contrast *barium enema). Magnetic resonance (MR) contrast agents contain either a positive contrast atom (usually gadolinium) to increase the signal or a negative contrast atom (such as iron) to decrease it. Ultrasound contrast medium consists of tiny (1–10 ?m diameter) bubbles of gas, which reflect back the sound waves strongly. They can also be made to resonate or rupture to increase the signal to the ultrasound probe.
A differential selective culture medium for Burkholderia pseudomallei, devised by Dr LesleyRichard Ashdown (1943-93), Townsville, Australia. B. pseudomallei grows as distinctive purple rugose colonies on this medium.... ashdown’s medium
n. 1. short for *contrast medium, e.g. post-contrast CT scan. 2. the difference in the shade of grey between different tissues on a diagnostic image, such as radiograph or CT scan (see grey scale).... contrast
deterioration in renal function (of more than 25%) after administration of radiocontrast material. Development of this condition is more likely when there is pre-existing renal disease (the most important factor) or diabetes, vasoconstriction, simultaneous use of NSAIDs, and large amounts of radiocontrast are used. It is thought that the radiocontrast induces vasoconstriction in the vessels supplying the medulla of the kidney and aggravates hypoxia in this part of the kidney.... contrast nephropathy
n. 1. any substance, usually a broth, agar, or gelatin, used for the *culture of microorganisms or tissue cells. An assay medium is used to determine the concentration of a growth factor or chemical by measuring the amount of growth it produces in a particular microorganism; all other nutrients are present in amounts adequate for growth. 2. see contrast medium.... medium
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