What is "contrast medium"

n. (context medicine English) Any substance, such as barium sulfate, used in radiography to increase the visibility of internal structures

n. 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]

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.