Motivation: Odd-even phase errors are a long-standing problem for EPI, especially in cases with strong gradient systems and high field strengths. Goal(s): To enable high-quality odd-even correction in challenging cases using field-correcting GRAPPA (FCG). Approach: the FCG technique was applied to in vivo studies for 1-mm 3D EPI (CAIPI undersampling R=4) at 7T system, and 2D EPI (SMS=1-4, R=2-4) at 3T high-performance system through a straightforward and flexible pipeline for separate ghost correction and image reconstruction. Results: FCG produced the best correction and cleanest output on challenging cases. The pipeline is effective and flexible for different EPI structures and different vendors. Impact: A field-correcting GRAPPA (FCG) technique for high-quality correction of odd-even phase errors in EPI and a flexible pipeline for separate data correction and reconstruction was developed and validated, unleashing EPI applications for higher undersampling, stronger gradient systems, and higher fields.
Wang et al. (Tue,) studied this question.