Concurrent Correction of Geometric Distortion and Motion Using the Map-Slice-to-Volume Method in Echo-Planar Imaging

摘要

The accuracy of measuring voxel intensity changes between stimulus and rest images in fMRI echo-planar imaging (EPI) data is severelydegraded in the presence of head motion. In addition, EPI is sensitive to susceptibility-induced geometric distortions. Head motion causesimage shifts and associated field map changes that induce different geometric distortion at different time points. Conventionally, geometricdistortion is “corrected” with a static field map independently of image registration. That approach ignores all field map changes induced byhead motion. This work evaluates the improved motion correction capability of mapping slice to volume with concurrent iterative fieldcorrected reconstruction using updated field maps derived from an initial static field map that has been spatially transformed and resampled.It accounts for motion-induced field map changes for translational and in-plane rotation motion. The results from simulated EPI time seriesdata, in which motion, image intensity and activation ground truths are available, show improved accuracy in image registration, fieldcorrected image reconstruction and activation detection.