Framewise distortion correction in Multi-echo Echo Planar Imaging

Echo Planar Imaging (EPI) suffers from off-resonance image distortion due to B0 inhomogeneities. These distortions are typically corrected by separate field map acquisitions, but only allow for sparse temporal sampling of B0 inhomogeneity. This approach prevents distortion correction if changes in the B0 field occur over time due to motion. Here, we present a method of correcting off-resonance distortion by computing a time series of field maps using phase information from multi-echo (ME) EPI data. We show that our method produces corrections comparable to the current standard of distortion correction, in addition to enabling frame-by-frame correction in functional MRI data.