Contrast Materials

Contrast materials, also called Contrast Agents or contrast media, are used to improve pictures of the inside of the body produced by x-rays, computed tomography (CT), magnetic resonance (MR) imaging, and ultrasound. Often, contrast materials allow the radiologist to distinguish normal from abnormal conditions.

Contrast materials are not dyes that permanently discolor internal organs. They are substances that temporarily change the way x-rays or other imaging tools interact with the body . When introduced into the body prior to an imaging exam, contrast materials make certain structures or tissues in the body appear different on the images than they would if no contrast material had been administered. Contrast materials help distinguish or “contrast” selected areas of the body from surrounding tissue. By improving the visibility of specific organs, blood vessels or tissues, contrast materials help physicians diagnose medical conditions.

Contrast materials enter the body in one of three ways. They can be:

• swallowed (taken by mouth or orally)
• administered by enema (given rectally)
• injected into a blood vessel (vein or artery; also called given intravenously or intra-arterially)

There are several types of contrast materials:

• Iodine based and Barium Sulfate compounds are used in x-ray and computed tomography (CT) imaging exams.
• Gadolinium is the key component of the contrast material most often used in magnetic resonance (MR) exams.
• Saline (salt water) and air are also used as contrast materials in imaging exams. Microbubbles and microspheres have been administered for ultrasound imaging exams, particularly exams of the heart.