Nuclear magnetic resonance imaging: methods and current status

Nuclear magnetic resonance (NMR) is a new noninvasive tool for the imaging specialist. Images are produced, not with X rays, but through the use of radio waves that stimulate transitions between "spin states" of nuclei in a magnetic field. The time required for the nucleus to return to equilibrium gives information about the environment of that nucleus. In this way, tissue chemical abnormalities such as detection of carcinoma and elucidation of metabolic pathways can be determined in vivo. Clinical experience is being accumulated which seems to indicate a role for NMR in the diagnostic evaluation of patients.