Dynamic Geometric Distortion Correction for Quantitative Susceptibility Mapping Using a Multi-Echo 2D-EPI Sequence

Echo planar imaging (EPI) suffers from geometric distortions, which can be corrected using reference acquisitions for single-echo EPI, or using field maps calculated from the multiple echoes in multi-echo EPI. The effect of distortion on EPI quantitative susceptibility mapping (QSM) has not been investigated. We compared static and dynamic geometric distortion correction for magnitude images and QSM using multi-echo 2D-EPI acquisitions with and without changes in head position. Multi-echo EPI corrected distortion in both magnitude and QSM images without the need for reference scans. Correcting the local field map in the QSM pipeline was optimal to reduce temporal variance.