Three-dimensional echo-shifted echo planar imaging with simultaneous blip-up and blip-down acquisitions for correcting geometric distortion

Geometric distortion is a prevalent image artifact in echo planar imaging (EPI). In a method known as BUDA (blip-up/down acquisition), k-space model-based reconstruction of two EPI datasets acquired separately with opposing phase-encoding polarities has been shown to reduce image distortions. A main disadvantage is that the two-shot acquisition strategy doubles the scan time and increases vulnerability to motion. We herein introduce a novel sequence – 3D echo-shifted EPI with BUDA (esEPI-BUDA) – to address the aforementioned issues by integrating the two acquisitions into one shot. We have successfully applied the 3D esEPI-BUDA technique to functional MRI.