A Multi-scale Kernel Bundle for LDDMM: Towards Sparse Deformation Description Across Space and Scales
Abstract
The Large Deformation Diffeomorphic Metric Mapping frame- work constitutes a widely used and mathematically well-founded setup for registration in medical imaging. At its heart lies the notion of the regularization kernel, and the choice of kernel greatly affects the results of registrations. This paper presents an extension of the LDDMM frame- work allowing multiple kernels at multiple scales to be incorporated in each registration while preserving many of the mathematical properties of standard LDDMM. On a dataset of landmarks from lung CT images, we show by example the influence of the kernel size in standard LDDMM, and we demonstrate how our framework, LDDKBM, automatically in- corporates the advantages of each scale to reach the same accuracy as the standard method optimally tuned with respect to scale. The frame- work, which is not limited to landmark data, thus removes the need for classical scale selection. Moreover, by decoupling the momentum across scales, it promises to provide better interpolation properties, to allow sparse descriptions of the total deformation, to remove the trade-off be- tween match quality and regularity, and to allow for momentum based statistics using scale information.