A new method of measuring static field distribution using modified Fourier NMR imaging

Abstract

A new method for mapping the static magnetic field of NMR imagers is presented. The method uses a conventional Fourier imaging pulse-sequence with the exception that the time interval between the 90 degrees and 180 degrees pulses does not equal that between the 180 degrees pulse and spin-echo formation. In images obtained from the pulse sequence, the difference between those two time intervals causes phase shifts that depend on the static magnetic field distribution. Thus, the information on the field distribution can be extracted from these phase shifts. This method is quicker and more easily implemented than the method proposed by Maudsley et al. (1979, 1983, 1984).