Medical Image Registration Incorporating Deformations

Multiple sources of 3D medical image data can be used to construct detailed patient representations. Typically registration is achieved assuming the validity of rigid body transformation. In many applications, and in particular when updating representations used for guidance during surgery and therapeutic interventions, this assumption is inappropriate. In this paper we describe a general method for 3D deformation, show how registration can incorporate a composite of rigid body and deformation components and illustrate this methodology on 3 example sets of images. The first is a repeated 3D MR scan of the abdomen of a volunteer who purposely changed position between scans; the second is an MR and CT scan of the head and neck, in which the patient was in a different position for the two scans; and the third is a set of MR and CT images of the head taken before and after epilepsy surgery. Non rigid deformation and composite warping showed significant improvement in registration accuracy in each case.