Concurrent Geometric Distortion Correction in Mapping Slice-to-volume (MSV) Motion Correction of fMRI Time Series
Fessler J, Kim B, Yeo D
University of Michigan, University of Michigan Medical School
The accuracy of measuring voxel intensity changes between stimulus and rest images in fMRI echo-planar imaging (EPI) data, from which brain activation maps are computed, is severely degraded in the presence of head motion. In addition, EPI is sensitive to susceptibility-induced geometric distortions. Head motion causes image shifts as well as field-map changes which result in local changes in geometric distortion. Conventionally, geometric distortion correction is performed, with a static field-map, independently of image registration. This does not account for field-map changes with head motion. This work evaluates the improved motion correction capability of MSV with concurrent iterative field-corrected reconstruction using only an initial field-map. The results from simulated motion EPI data show improved accuracy in image registration and field-corrected reconstruction for the correction of image artifacts complicated by the motion induced field effects.