Magnetic Resonance Imaging (MRI) is a high quality method of imaging the interior of the body using the effect of magnetic waves on hydrogen protons. During varying periods and intensities of magnetization of hydrogen, the molecules align. Observing the relaxation time of the molecules after the magnet is turned off (the time it takes for the molecules to return to their normal orientation), a radio frequency wave is used to gather information and translated by a computer to produce a detailed visual image.

MRI is an excellent modality for the evaluation of soft tissue, since these tissues contain the most hydrogen. MRI is good at imaging bone as well.

Contrast agents, such as gadolinium can be used with MRI to detect tumors and their composition, inflammation, and to evaluate changes due to surgery and infection.