title: Surface matching for high-accuracy registration of the lateral skull base.
abstract: OBJECTIVE
  The accuracy achievable when utilizing image guidance depends to a large extent on the accuracy with which the patient can be registered to preoperative image data. This work proposes a method for the registration of the temporal bone based on surface matching and investigates the achievable accuracy of the technique.
  
  
  METHODS
  Fourteen human temporal bones were utilized for evaluation; incisions were made, fiducial screws were implanted to act as a ground truth, and imaging was performed. The positions of the fiducials and surface of the mastoid were extracted from image data and reference positions defined at the round window and the mastoid surface. The surface of the bone was then digitized using a tracked pointer within the region exposed by the incisions and the physical and image point clouds registered, with the result compared to the fiducial-based registration.
  
  
  RESULTS
  Results of one case were excluded due to a problem with the ground truth registration. In the remaining cases an accuracy of [Formula: see text] and [Formula: see text] mm was observed relative to the ground truth at the surface of the mastoid and round window, respectively.
  
  
  CONCLUSIONS
  A technique for the registration of the temporal bone was proposed, based on surface matching after exposure of the mastoid surface, and evaluated on human temporal bone specimens. The results reveal that high-accuracy patient-to-image registration is possible without the use of fiducial screws.
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland.|Institute of Forming Technology and Equipment, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Chaozheng
authors.initials: C
authors.lastname: Zhou
authors.affiliation: Department for ENT, Head and Neck Surgery, Bern University Hospital, Bern, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Anschuetz
authors.affiliation: Department for ENT, Head and Neck Surgery, Bern University Hospital, Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Weder
authors.affiliation: Institute of Forming Technology and Equipment, Shanghai Jiao Tong University, Shanghai, China. lexie@sjtu.edu.cn.
authors.forename: Le
authors.initials: L
authors.lastname: Xie
authors.affiliation: Department for ENT, Head and Neck Surgery, Bern University Hospital, Bern, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Caversaccio
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Weber
authors.affiliation: ARTORG Center for Biomedical Engineering, University of Bern, Bern, Switzerland. tom.williamson@artorg.unibe.ch.
authors.forename: Tom
authors.initials: T
authors.lastname: Williamson
mesh_terms: D006801:Humans; D007091:Image Processing, Computer-Assisted; D008416:Mastoid / Q000000981:diagnostic imaging / Q000601:surgery; D019291:Skull Base / Q000000981:diagnostic imaging* / Q000601:surgery; D025321:Surgery, Computer-Assisted / Q000379:methods; D013701:Temporal Bone / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: ICP algorithm; Patient-to-image registration; Surface matching; Surgical navigation