title: New Protocol for Skin Landmark Registration in Image-Guided Neurosurgery: Technical Note.
abstract: BACKGROUND
  Newer versions of the commercial Medtronic StealthStation allow the use of only 8 landmark pairs for patient-to-image registration as opposed to 9 landmarks in older systems. The choice of which landmark pair to drop in these newer systems can have an effect on the quality of the patient-to-image registration.
  
  
  OBJECTIVE
  To investigate 4 landmark registration protocols based on 8 landmark pairs and compare the resulting registration accuracy with a 9-landmark protocol.
  
  
  METHODS
  Four different protocols were tested on both phantoms and patients. Two of the protocols involved using 4 ear landmarks and 4 facial landmarks and the other 2 involved using 3 ear landmarks and 5 facial landmarks. Both the fiducial registration error and target registration error were evaluated for each of the different protocols to determine any difference between them and the 9-landmark protocol.
  
  
  RESULTS
  No difference in fiducial registration error was found between any of the 8-landmark protocols and the 9-landmark protocol. A significant decrease (P < .05) in target registration error was found when using a protocol based on 4 ear landmarks and 4 facial landmarks compared with the other protocols based on 3 ear landmarks.
  
  
  CONCLUSIONS
  When using 8 landmarks to perform the patient-to-image registration, the protocol using 4 ear landmarks and 4 facial landmarks greatly outperformed the other 8-landmark protocols and 9-landmark protocol, resulting in the lowest target registration error.
authors.affiliation: *McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada; ‡Department of Biomedical Engineering, McGill University, Montreal, Quebec, Canada; §Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada; ¶Neuronavigation Unit, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Gerard
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Hall
authors.forename: Kelvin
authors.initials: K
authors.lastname: Mok
authors.forename: D Louis
authors.initials: DL
authors.lastname: Collins
mesh_terms: D000465:Algorithms; D059925:Anatomic Landmarks; D002983:Clinical Competence; D002985:Clinical Protocols; D005145:Face / Q000033:anatomy & histology; D006801:Humans; D038361:Neuronavigation; D019635:Neurosurgical Procedures / Q000379:methods*; D019047:Phantoms, Imaging; D012867:Skin / Q000033:anatomy & histology*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed