Discontinuity preserving registration of abdominal MR images with apparent sliding organ motion

Abstract

Discontinuous displacement fields are quite common in the medical field, in particular at organ boundaries with breathing induced organ motion. The sliding motion of the liver along the abdominal wall clearly causes a discontinuous displacement field. Today's common medical image registration methods, however, cannot properly deal with this kind of motion as their regularisation term enforces a smooth displacement field. Since these motion discontinuities appear at organ boundaries, motion segmentation could play an important guiding role during registration. In this paper we propose a novel method that integrates registration and globally optimal motion segmentation in a variational framework. The energy functional is formulated such that the segmentation, via continuous cuts, supports the computation of discontinuous displacement fields. The proposed energy functional is then minimised in a coarse-to-fine strategy by using a fast dual method for motion segmentation and a fixed point iteration scheme for motion estimation. Experimental results are shown for synthetic and real MR images of breathing induced liver motion. © 2012 Springer-Verlag.