A contrast agent is a substance used to enhance the visualization of a body part during a diagnostic imaging procedure. The agent may be introduced into a bodily cavity, consumed orally, or injected intravenously. Some examples of contrast agents include barium (for x-rays), iodine (for x-rays), gadolinium (for MRI), and bubbles (for ultrasound). Contrast agents are highly effective at helping clinicians to better see certain parts of human anatomy and assess their function.
Contrast agents are generally safe to use. However, certain medical conditions may cause an undesirable reaction that can range in severity. Risk factors may include
- allergies to contrast agents,
- other pre-existing medical conditions, or
- taking other medications that are contraindicated to the contrast medium.
As a result, some individuals may need to undergo a medical test or screening before they are cleared to receive contrast agent for an imaging procedure. Contrast agents are removed from the body over time through normal processes.