MRI contrast agents are substances used during Magnetic Resonance Imaging (MRI) to enhance the visibility of internal structures. These agents help differentiate between normal and abnormal tissues, making it easier for doctors to diagnose conditions. They are typically injected into a patient's bloodstream and can highlight blood vessels, tumors, and other areas of interest. The most common type of MRI contrast agent contains gadolinium, a rare earth metal. Gadolinium-based agents are generally safe, but they can cause allergic reactions in some individuals. Patients with kidney issues may require special consideration, as gadolinium can pose risks in those with impaired kidney function.