Thomas Benner1, Andre J. W. van Der Kouwe1, Caterina Mainero1, Dominic Holland2, Anders M. Dale2
1Radiology, Athinoula A. Martinos Center, Charlestown, MA, United States; 2Multimodal Imaging Laboratory,, University of California, San Diego, La Jolla, CA, United States
Single-shot EPI suffers from spatial and intensity distortions caused by B0 field inhomogeneities. For comparison with anatomical MRI scans, undistorted images are highly desirable. We demonstrate a fully automatic version of a method to correct geometric distortions as implemented on Siemens MRI scanners. The method involves a displacement mapping scan based on two EPI scans with opposed phase encoding polarities together with a fast nonlinear alignment procedure. Results show better match of unwrapped data to the anatomical data as demonstrated in BOLD and DTI scans. The method has also been implemented in other EPI scans like PACE and ASL.