Kjems, Ulrik3; Storther, Stephen C.4; Anderson, Jon4; Law, Ian4; Hansen, Lars Kai5
1 Department of Informatics and Mathematical Modeling, Technical University of Denmark2 Cognitive Systems, Department of Informatics and Mathematical Modeling, Technical University of Denmark3 Risø National Laboratory for Sustainable Energy, Technical University of Denmark4 unknown5 Copenhagen Center for Health Technology, Center, Technical University of Denmark
This paper addresses the problem of neuro-anatomical registration across individuals for functional [15O]water PET activation studies. A new algorithm for 3D non-linear structural registration (warping) of MR scans is presented. The method performs a hierarchically scaled search for a displacement field maximizing one of several voxel similarity measures derived from the two dimensional histogram of matched image intensities, subject to a regularizer that ensures smoothness of the displacement field. The effect of the non-line ar structural registration is studied when it is computed on anatomical MR scans and applied to co-registered [15O] water PET scans from the same subjects; in this experiment a study of visually guided saccadic eye movements. The performance of the non-linear warp is evaluated using multivariate functional signal and noise measures. These measures prove to be useful for comparing different inter-subject registration approaches, e.g. affine versus non-linear. A comparison of 12-parameter affine registration versus non-linear registration demonstrates that the proposed non-linear method increases the number of voxels retained in the cross-subject mask. We demonstrate that improved structural registration may result in an improved multivariate functional signal-tonoise ratio. Furthermore registration of PET scans using the 12-parameter affine transformations that align the co-registered MR images does not improve registration compared to 12-parameter affine alignment of the PET images directly.
I E E E Transactions on Medical Imaging, 1999, Vol 18, Issue 4, p. 306-319