title: Fieldmap-free retrospective registration and distortion correction for EPI-based functional imaging.
abstract: We describe a method for correcting the distortions present in echo planar images (EPI) and registering the EPI to structural MRI. A fieldmap is predicted from an air / tissue segmentation of the MRI using a perturbation method and subsequently used to unwarp the EPI data. Shim and other missing parameters are estimated by registration. We obtain results that are similar to those obtained using fieldmaps, however neither fieldmaps, nor knowledge of shim coefficients is required.
authors.affiliation: Computer Science and Artificial Intelligence Lab, MIT, USA.
authors.forename: Clare
authors.initials: C
authors.lastname: Poynton
authors.forename: Mark
authors.initials: M
authors.lastname: Jenkinson
authors.forename: Stephen
authors.initials: S
authors.lastname: Whalen
authors.forename: Alexandra J
authors.initials: AJ
authors.lastname: Golby
authors.forename: William
authors.initials: W
authors.lastname: Wells
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001185:Artificial Intelligence; D001921:Brain / Q000033:anatomy & histology*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique