Sune Darkner1, Matthew George Liptrot1, Jon Sporring1
1Department of Computer Science, University of Copenhagen, Copenhagen, Denmark
Many of the analysis methods applied to neuroimaging are dependent upon correct co-registration of datasets. The direction in which the registration is applied (image A registered to image B, or vice-versa) may vary depending upon the topic of interest without consideration of possible confounds this may involve. Here we show how even affine registration is subject to inverse inconsistency, where the co-registration result is different depending upon the direction chosen. A difference of 0.5 voxels is demonstrated for a pure translational, affine registration. Care must therefore be taken when performing co-registration in order to minimize subsequent directionality-based confounds.