title: Updating navigation with intraoperative image data.
abstract: OBJECTIVE
  To localize overlooked tumor remnants by updating navigation with intraoperative magnetic resonance imaging compensating for the effects of brain shift.
  
  
  METHODS
  In 112 patients among 805 patients that were investigated by combined use of intraoperative high-field (1.5 T) magnetic resonance imaging and navigation, mostly glioma cases (n = 85), an update of the navigation was performed. Intraoperative image data were rigidly registered with the preoperative image data, the tumor remnant was segmented, and then the initial patient registration was restored so that the registration coordinate system of the preoperative image data was applied on the intraoperative images, allowing navigation updating without intraoperative patient re-registration.
  
  
  RESULTS
  Navigation could be updated reliably in all cases. Potential positional shifting impairing the initial update strategy was observed only in 2 cases so that a patient re-registration was necessary. The target registration error of the initial patient registration was 1.33 +/- 0.63 mm, and registration of preoperative and intraoperative images could be performed with high accuracy, as proven by landmark checks. Updating of navigation resulted in increased resections or correction of a catheter position or biopsy sampling site in 94%. In the remaining 7 patients, the intraoperative images were used for correlation with the surgical site but without changing the surgical strategy.
  
  
  CONCLUSIONS
  Navigation can be reliably updated with intraoperative image data without repeated patient registration, facilitating the update procedure. Updated navigation allows achieving enlarged resections and compensates for the effects of brain shift.
authors.affiliation: Department of Neurosurgery, University Erlangen-Nuremberg, Erlangen, Germany. nimsky@med.uni-marburg.de
authors.forename: Christopher
authors.initials: C
authors.lastname: Nimsky
authors.forename: Boris
authors.initials: B
authors.lastname: von Keller
authors.forename: Sven
authors.initials: S
authors.lastname: Schlaffer
authors.forename: Daniela
authors.initials: D
authors.lastname: Kuhnt
authors.forename: Daniel
authors.initials: D
authors.lastname: Weigel
authors.forename: Oliver
authors.initials: O
authors.lastname: Ganslandt
authors.forename: Michael
authors.initials: M
authors.lastname: Buchfelder
mesh_terms: D000328:Adult; D001927:Brain Diseases / Q000473:pathology* / Q000601:surgery*; D003399:Craniotomy / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018579:Patient Selection; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*