Robust method for EPI ghost correction

Introduction: An important step in the reconstruction of an EPI scan is the phase correction between the odd and even lines to reduce the Nyquist ghost. Typically, the correction is performed for each channel, slice, and repetition of a data set separately. We propose a phase correction technique, which determines the phase correction differences between channels and slices with high accuracy in a preparation step from a set of navigator echoes. Taking this calibration into account, only one single correction needs to be determined dynamically for all slices and channels during the EPI series, greatly improving stability. Thus, the information in the navigator echoes can be optimally combined favoring strong signals and avoiding correction of low signal region (e.g. away from small receiver coils) with noise navigators.