METHOD OF ELIMINATING EFFECTS OF SPURIOUS FREE INDUCTION DECAY NMR SIGNAL CAUSED BY IMPERFECT 180GRAD RF PULSES

摘要

A method for eliminating the effects of a spurious free induction decay (FID) NMR signal due to imperfect 180° RF pulses comprises applying a large magnitude, short duration magnetic field gradient pulse, termed the "crusher" pulse immediately following the 180° pulse. When the method is employed with NMR pulse sequences in which the 180. degree. pulse is part of a spin echo type refocusing RF pulse sequence, the 180° pulse is preceded by a magnetic field gradient pulse termed the "primer", having an equal integral with respect to time as the crusher pulse. The method is effective in removing NMR image artifacts produced by spurious FID in both planar and three- dimensional NMR imaging methods.