title: Quantification of true in vivo (application) accuracy in cranial image-guided surgery: influence of mode of patient registration.
abstract: OBJECTIVE
  Very few studies have attempted to quantify the true (application) accuracy of image-guidance systems during craniotomy. This is, in part, because of the lack of millimetric intraoperative targets to allow such measurements. Few in vivo studies have compared the influence of mode of patient registration on subsequent true accuracy.
  
  
  METHODS
  Seven modes of patient registration (anatomic landmarks, 5 or 10 adhesive fiducials, bone-implanted fiducials [Stryker-Leibinger], surface matching using 45 or 100 points over scalp convexity or nose/auditory meatus contours) were compared. Thirty patients were involved in the study. Millimetric targets (bone drill holes or deep 1-mm titanium hemoclips) were placed then localized and saved at surgery. These targets were then identified on postoperative volumetric computed tomography fused with operative data sets. Localization errors of the targets were measured for each registration on an optical image-guidance system (StealthStation).
  
  
  RESULTS
  Only implanted cranial fiducials had a statistically significant accuracy advantage (1.7 +/- 0.7 mm). All other registrations had similar accuracies (approximately 4.0 +/- 1.7 mm) except anatomic landmarks, which were worse (4.8 +/- 1.9 mm). Calculated accuracies (root mean squared) had no predictive value for true (application) accuracies.
  
  
  CONCLUSIONS
  Not surprisingly, application accuracy of image-guidance is worse without implanted cranial markers. Unexpectedly, there was no major difference in localization of deep targets between the other registrations tested in this study. Care must be taken when using image-guidance tools to consider error introduced by registration. Cranium-implanted fiducials should be considered when high accuracy and reproducibility are needed.
authors.affiliation: Department of Neurosurgery, Toulouse University Hospitals, Toulouse-Rangueil, France. MascottDonnelly@netscape.net
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Mascott
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Sol
authors.forename: Philippe
authors.initials: P
authors.lastname: Bousquet
authors.forename: Jacques
authors.initials: J
authors.lastname: Lagarrigue
authors.forename: Yves
authors.initials: Y
authors.lastname: Lazorthes
authors.forename: Valérie
authors.initials: V
authors.lastname: Lauwers-Cances
mesh_terms: D000886:Anthropometry / Q000295:instrumentation / Q000379:methods; D001921:Brain / Q000033:anatomy & histology / Q000601:surgery; D003399:Craniotomy / Q000295:instrumentation / Q000379:methods*; D006257:Head / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D038361:Neuronavigation / Q000295:instrumentation* / Q000379:methods; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000295:instrumentation / Q000379:methods; D019736:Prostheses and Implants / Q000592:standards / Q000639:trends*; D015203:Reproducibility of Results; D012886:Skull / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D013525:Surgical Instruments / Q000592:standards / Q000639:trends; D014025:Titanium; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods
chemical_list: D014025:Titanium