A brain imaging technique that uses a magnetic field and radio waves to produce an image. Also known as magnetic resonance imaging (MRI).
A new, noninvasive diagnostic method that uses magnetic forces to produce cross-sectional images of body structures; also called magnetic resonance imaging.
A phenomenon in which the atomic nuclei of certain materials placed in a strong, static magnetic field will absorb radio waves supplied by a transmitter at particular frequencies. The energy of the radio frequency photons promotes the nucleus from a low-energy state, in which the nuclear spin is aligned parallel to the strong magnetic field, to a higher energy state in which the nuclear spin has a component transverse or opposed to the field. These nuclei will occasionally revert to the lower energy state by emitting photons at characteristic (resonance) frequencies, providing information about the local magnetic field at the nucleus. The rate at which the nuclei revert (relax) to the lower energy state when the source of radio waves is turned off is another important factor.
A physical phenomenon brought about in the body by subjecting the body to radio frequency fields in a strong magnetic field. It does not use radioactive materials or x-rays. NMRis used in nuclear magnetic resonance imaging (NMRI) and the study of certain biochemical activity.