EPI Distortion Correction with ORACLE

Wei Lin¹, Feng Huang¹, Enrico Simonotto¹, Randy Duensing¹

A rapid EPI distortion correction method is proposed by off-resonance artifacts correction with convolution in k-space (ORACLE). A basis kernel is first computed by k-space data fitting between two EPI datasets with slightly different echo times. A B0 map is then computed from the inverse Fourier Transform of this basis kernel, resulting in robust estimations even in low signal intensity regions. Then different convolution kernels are applied to different phase-encoding lines to correct for EPI distortion directly in the k-space. in vivo brain DWI study demonstrates excellent correction results. An additional advantage of ORACLE is the reusability of correction kernels for images acquired with the same sequence but different contrasts.