Groupwise whole-body MR image registration guided by zero-average volume changes

Abstract: Imiomics (imaging-omics) is an image analysis technique developed at Uppsala University that allows statistical analysis of whole-body image data from scans of multiple subjects. The process requires a common coordinate system for all the images, currently obtained by manually selecting a subject from the cohort with average anatomical parameters, to which all the subjects are registered.While a wide collection of groupwise registration methods has been proposed in the field of neuroimaging, the different nature of whole-body image registration and its specific problems do not allow their direct application without further adaption. This work proposes an approach that refines a manual initial choice of the reference, warping it with a deformation field that brings the voxel-wise average volume change associated to the mapping of all the images in the cohort to zero. A method for the generation of deformation fields with known volume changes was implemented, and experiments on synthetic and real data were performed in order to evaluate the impact of this approach on the quality of the registration. Results on fat/water separated whole-body magnetic resonance (MR) images show a decrease of the registration error of about 8% in terms of inverse consistency and mean squared error.