MR imaging is generally considered to be safe and millions of people have MRI scans every year without problems but accidents, injuries, and even deaths have occurred during MRI procedures. Such adverse events are extremely rare if appropriate safety precautions are followed. Serious complications can occur in people who have pacemakers, metallic particles in their eyes, or certain types of metal prostheses or medical implants. A researcher or technologist will review safety information with you before the scan. In order to determine whether it is safe for you to have the MRI scan, it will be important that you tell the technologist about any metallic objects or devices in or on your body. You will be provided with a squeeze ball that will enable you to contact the MRI and research staff at any time during your scan.