a diagnostic radiologic modality, using nuclear magnetic resonance technology, in which the magnetic nuclei (especially protons) of a patient are aligned in a strong, uniform magnetic field, absorb energy from tuned radiofrequency pulses, and emit radiofrequency signals as their excitation decays. These signals, which vary in intensity according to nuclear abundance and molecular chemical environment, are converted into sets of tomographic images by using field gradients in the magnetic field, which permits 3-dimensional localization of the point sources of the signals. SYN: nuclear magnetic resonance imaging, NMR imaging, nuclear magnetic resonance tomography. Magnetic resonance imaging (MRI) and Medical tests