Nonrigid image registration is widely used to estimatetissue deformations in highly deformable anatomies. Amongthe existing methods, nonparametric registration algorithmssuch as optical flow, or Demons, usually have the advantage ofbeing fast and easy to use. Recently, a diffeomorphic versionof the Demons algorithm was proposed. This provides theadvantage of producing invertible displacement fields, whichis a necessary condition for these to be physical. However,such methods are based on the matching of intensities andare not suitable for registering images with different contrastenhancement. In such cases, a registration method based on thelocal phase like the Morphons has to be used. In this paper, adiffeomorphic version of the Morphons registration method isproposed and compared to conventional Morphons, Demons,and diffeomorphic Demons. The method is validated in thecontext of radiotherapy for lung cancer patients on several4D respiratory-correlated CT scans of the thorax with and withoutvariable contrast enhancement.
展开▼
