Patent ID: 6369568
Filing Date: 2002-04-09
Classification: G01R

Abstract:
In a magnetic resonance imaging system which performs a scan to acquire MR data using a fast spin echo (FSE) pulse sequence in which an RF magnetic field is produced by an RF excitation pulse followed by a series of RF refocusing pulses and readout, phase-encoding and slice-select magnetic field gradients are applied to spatially encode echo signals that are acquired during the pulse sequence, a prescan in which the FSE pulse sequence is adjusted prior to conducting the scan, which comprises:a) acquiring MR data using a first modified FSE pulse sequence; b) calculating first order phase error that corresponds to readout gradient corrections from the MR data acquired in step a); c) acquiring MR data using a second modified FSE pulse sequence; d) calculating first order phase error that corresponds to phase-encoding gradient corrections from the MR data acquired in step c) e) calculating zeroth order phase error that corresponds to spatially invariant magnetic field corrections from the MR data acquired in step a) or step c); f) acquiring MR data using a third modified FSE pulse sequence; g) calculating a first order phase error that corresponds to slice-select gradient correction from the MR data acquired in step f); and h) adjusting the FSE pulse sequence with the phase shift corrections calculated in steps b), d), e) and g).