A substance administered during a medical imaging examination to make particular tissues, organs, blood vessels, or other structures easier to distinguish.
A contrast agent changes the appearance of certain structures on an imaging study, helping healthcare professionals see anatomical features or abnormalities more clearly. Different imaging techniques use different types of contrast agents.
For example, iodinated contrast agents are commonly used in CT, while gadolinium-based contrast agents may be used in MRI. Some contrast agents are swallowed or injected, depending on the examination and the body area being assessed.
Contrast agents are not themselves treatments for the condition being investigated, although they can make diagnosis more accurate.
COMMONLY CONFUSED WITH
- Contrast: the difference in appearance between adjacent structures on an image; a contrast agent is a substance used to enhance that difference.
- Tracer: a substance used in certain nuclear medicine examinations to track physiological processes; it serves a different imaging purpose.
SEE ALSO