This is a brief introduction to the COPE (Correction based on Opposite Phase Encoding) plugin for EPI distortion correction.
Due to the susceptibility artifact, echo planar imaging (EPI) data can be deformed. There are several approaches to alleviate the problem. One approach is to calculate and apply the pixelshift map from a B0 map from the static magnetic field to EPI data (, ); the anatabacus plugin in BrainVoyager can be used for this approach. Another approach is based on reverse phase encoded EPI datasets, where image registration is used to compose a shift/voxel displacement map. An example is Andersson's approach  or Ruthotto's correction method .
This is an early version (version 0.5) of the plugin to correct EPI images using reverse phase encoded data sets. Please consult the BrainVoyager support site for updates.
This plugin version was tested on BrainVoyager QX 2.8. It might or might not work on previous versions.
 Jezzard, P. & Balaban, B.S. (1995). Correction for Geometric Distortion in Echo Planar Images from B0 Field Variations. MRM, 34:65-73.
 Implementation of : Breman, H., Peters, J., Ashburner, J., Weiskopf, N. and Goebel, R. (2009), NeuroImage 47, Supplement 1, S81. See also anatabacus.
 Andersson, J.L.R. and Skare, S. (2001) A Model-Based Method for Retrospective Correction of Geometric Distortions in Diffusion-Weighted EPI. NeuroImage 16, 177-199.
 Ruthotto, L, Mohammadi, S, Heck, C, Modersitzki, J, and Weiskopf, N. (2013) HySCO - Hyperelastic Susceptibility Artifact Correction of DTI in SPM. Presented at the Bildverarbeitung fuer die Medizin 2013.
Latest update of this page: 05 March 2015