Contrast agents are used with imaging tests for diagnostic purposes. These agents work by improving the contrast of structures or fluids within your body during imaging tests like X-rays, CT scans, and MRIs, making it easier for healthcare professionals to see what's going on inside. Some contrast agents are taken orally, while others are injected into your bloodstream. Examples include gadobutrol (Gadavist), iohexol (Omnipaque), and ioversol (Optiray 240). These medications can help your care team see inside your body more clearly.