What is a contrast agent?

What is a contrast medium?

Contrast media are drugs that are generally administered directly into veins, arteries or joints, or are taken by mouth. They are used to visualize organs such as the brain, kidneys, liver, blood vessels and stomach and any abnormalities affecting them.

Three main contrast media categories

For X-ray procedures:

  • iodinated contrast media for most examinations
  • barium media for examinations of the digestive tract

For magnetic resonance imaging (MRI):

  • gadolinium complexes for all examinations