DefinitionA magnetic resonance imaging (MRI) scan of the leg is a noninvasive method to create detailed pictures of the leg, including the ankle, foot, and surrounding tissues.A leg MRI also creates pictures of the knee. However, the knee is discussed in a separate article. See also: MRI of the knee.Unlike x-raysand computed tomographic (CT) scans, which use radiation, MRI uses powerful magnets and radio waves. The MRI scanner contains the magnet. The magnetic field produced by an MRI is about 10 thousand times greater than the earth's.The magnetic field forces hydrogen atoms in the body to line up in a certain way (similar to how the needle on a compass moves when you hold it near a magnet). When radio waves are sent toward the lined-up hydrogen atoms, they bounce back, and a computer rec