Fully automatic surface-based pre- to intra-operative CT registration for cochlear implant

Abstract

Percutaneous cochlear implantation (PCI) is an image-guided surgical approach, where access to the cochlea is achieved by drilling a channel from the outer skull to the cochlea. The PCI requires pre- and intra-operative planning. Computation of a safe drilling trajectory is performed in a pre-operative CT. This trajectory is mapped to intra-operative space using the transformation matrix that registers the pre- and intra-operative CTs. However, the misalignment between the two CTs is too extreme to be recovered by standard registration methods. Thus the registration is initialized manually. In this work we present a method that aligns the scans completely automatically. We compared the performance of this method to the manually initialized registration. There is a maximum difference of 0.19 mm between the entry and target points resulting from the automatic and manually initialized registrations. This suggests that the automatic method is accurate enough to be used in a PCI surgery. © 2012 Springer-Verlag.