Definition: A liquid dye prescribed by a doctor in order to visualize certain organs (e.g., the intestinal tract) and/or their arteries or veins. The contrast material can be taken by mouth, or injected into a blood vessel. The composition of the dye makes it appear bright on imaging studies such as x-rays, CT, or MRI scans.
Examples of commonly used dyes include barium to visualize the intestinal tract with X-rays or CT scans, iodinated dyes to visualize the blood vessels of the brain and other organs by X-ray or CT scans, and gadolinium to visualize blood vessels by MRI.
