Magnetic resonance imaging, also known as MRI, uses radio waves and a strong magnetic field instead of x-rays to provide clear, detailed pictures of internal organs and tissues. The MRI scanner is a tube surrounded by a giant circular magnet. The patient lies on a bed that goes into the magnet, and the magnet and radio waves send information into a computer. The computer processes the information and then produces an image. MRI helps physicians to diagnose brain tumors or eye and inner ear problems. Learn more about MRI procedures.