Low-Rank Constrained Reacquired-Navigator Reconstruction of multi-shot DWI.

Abstract

The Diffusion-Weighted Imaging (DWI) requires additional acquisition of phase correction data and parallel imaging prescan data to respectively suppress artifacts caused by odd-even echo errors and motion-induced phase errors. In this study, we propose subtle modifications to the widely used spin-echo DW sequence, wherein an additional 180° radiofrequency refocusing pulse is applied after the completion of image echoes to acquire fully sampled navigator-echo data. Our proposed approach draws parallels with the dual spin-echo DW technique. However, our methodology distinguishes itself by utilizing positive and negative gradients to independently capture fully sampled navigator-echo data. Following this, we employ algorithms grounded in low-rank constraints, in conjunction with the reacquired navigator-echo data to address the two major phase errors inherent in Multi-Shot DWI (MSDWI). Simulation studies and in vivo brain imaging experiments demonstrate that this approach effectively suppresses image artifacts caused by the phase error, without the need for additional time-consuming prescans.