Contrast agents are substances used to enhance the contrast of body structures or fluids during diagnostic imaging. Iodinated contrast agents are divided into two types: oil-soluble iodine contrast agents and water-soluble iodine contrast agents.

Iodinated contrast media (contrast agents) are used to enhance images of the inside of the body produced by X-rays and computed tomography (CT). Often, contrast media help doctors distinguish between normal and abnormal conditions in the body.