A Demons Algorithm for Image Registration with Locally Adaptive Regularization

Thirion's Demons [1] is a popular algorithm for nonrigid image registration because of its line linear computational complexity and ease of implementation. It approximately solves the diffusion registration problem [2] by successively estimating force vectors that drive the deformation toward alignment and smoothing the force vectors by Gaussian convolution. In this article, we show how the Demons algorithm can be generalized to allow image-driven locally adaptive regularization [3,4] in a manner that preserves both the linear complexity and ease of implementation of the original Demons algorithm. We show that the proposed algorithm exhibits lower target registration error and requires less computational effort effort the original Demons algorithm on the registration of serial chest CT scans of patients with lung nodules.