title: Do image modality and registration method influence the accuracy of craniofacial navigation?
abstract: OBJECTIVE
  Cone-beam computed tomography (CBCT) is increasingly used in craniofacial imaging and may be an interesting option for navigated surgery. The purpose of this study was to evaluate the accuracy of various registration techniques in CBCT compared with intraoperative and diagnostic multislice spiral computed tomography (MSCT).
  
  
  METHODS
  High-resolution images of an anthropomorphic skull phantom with target markers were obtained using 2 CBCT machines (KaVo 3D eXam, ILUMA), an intraoperative MSCT (Sensation Open), and the standard diagnostic MSCT (LightSpeed VCT). Bone markers, a registration template, and an external registration frame were used for registration with an optical-based navigation system. Target registration errors (TREs) were evaluated and statistically analyzed in SPSS (P < .05).
  
  
  RESULTS
  The mean ± standard deviation for overall TREs of the KaVo 3D eXam, ILUMA, Sensation Open, and LightSpeed VCT devices were 1.37 ± 0.54, 1.67 ± 0.65, 1.27 ± 0.52, and 1.31 ± 0.30 mm, respectively. The KaVo 3D eXam showed no significant differences compared with the MSCTs. The ILUMA imaged the external registration frame only marginally and showed significant higher TREs compared with the other registration methods (P < .001). In the 2 MSCTs, no significant differences between the registration methods were found.
  
  
  CONCLUSIONS
  CBCT and intraoperative MSCT may show comparable TREs as standard diagnostic MSCT. Bone markers are the gold standard. Registration templates and external registration frames are valuable alternatives. When using only external registration frames, CBCTs with a large scan field are recommended.
authors.affiliation: SIP-Department for Microinvasive Therapy, Medical University of Innsbruck, Innsbruck, Austria. gerlig.widmann@i-med.ac.at
authors.forename: Gerlig
authors.initials: G
authors.lastname: Widmann
authors.forename: Antoniette
authors.initials: A
authors.lastname: Zangerl
authors.forename: Peter
authors.initials: P
authors.lastname: Schullian
authors.forename: Martin
authors.initials: M
authors.lastname: Fasser
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Puelacher
authors.forename: Reto
authors.initials: R
authors.lastname: Bale
mesh_terms: D016477:Artifacts; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation / Q000592:standards*; D005147:Facial Bones / Q000000981:diagnostic imaging / Q000601:surgery*; D057918:Fiducial Markers; D005624:Frontal Bone / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000592:standards*; D007430:Intraoperative Care / Q000592:standards; D008416:Mastoid / Q000000981:diagnostic imaging; D061330:Multidetector Computed Tomography / Q000295:instrumentation / Q000592:standards*; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000592:standards; D012886:Skull / Q000000981:diagnostic imaging / Q000601:surgery*; D019291:Skull Base / Q000000981:diagnostic imaging; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000592:standards*; D013701:Temporal Bone / Q000000981:diagnostic imaging; D015050:Zygoma / Q000000981:diagnostic imaging