Single-shot Center-Overlapped EPI for distortion-frEe diffusion MRI (SCOPE)

Motivation: Single-shot EPI is prone to image distortion from B0 inhomogeneity and long echo time (TE), especially in diffusion MRI (dMRI). Goal(s): This study proposes a novel single-shot center-overlapped EPI readout, termed SCOPE, designed for distortion-free dMRI by correcting B0-induced distortions in each diffusion direction and reducing TE. Approach: SCOPE uses two overlapped k-space segments with opposing blip directions to derive ∆B0 maps directly from single-shot data, eliminating the need for additional acquisitions. The sequence was tested in vivo on 3T. Results: The SCOPE sequence produced high-fidelity dMRI images with minimal distortion, achieving effective distortion correction comparable to TOPUP-processed images. Impact: We proposed a novel single-shot center-overlapped EPI readout for distortion-free EPI, SCOPE. With overlapped segments, our method estimates the ∆B0 field map from the single-shot data for each diffusion direction. Further, our method has the potential to reduce the TE.