the absorption and emission of high-frequency radio waves by the nuclei of certain elements when placed in a strong magnetic field. The strongest signal is obtained from hydrogen atoms, which are abundant in the water and organic molecules in the body. In clinical use for magnetic resonance imaging, the signal is highly dependent on the concentration and mobility of water molecules within each tissue. NMR has important applications in noninvasive diagnostic techniques. See also magnetic resonance spectroscopy.
Medical dictionary. 2011.