title: In Vivo Accuracy of a Frameless Stereotactic Drilling Technique for Diagnostic Biopsies and Stereoelectroencephalography Depth Electrodes.
abstract: BACKGROUND
  Accurate frameless neuronavigation is highly important in cranial neurosurgery. The accuracy demonstrated in phantom models might not be representative for results in patients. Few studies describe the in vivo quantitative accuracy of neuronavigation in patients. The use of a frameless stereotactic drilling technique for stereoelectroencephalography depth electrode implantation in epilepsy patients, as well as diagnostic biopsies, provides a unique opportunity to assess the accuracy with postoperative imaging of preoperatively planned trajectories.
  
  
  METHODS
  In 7 patients with refractory epilepsy, 89 depth electrodes were implanted using a frameless stereotactic drilling technique. Each electrode was planned on a preoperative magnetic resonance and computed tomographic scan, and verified on postoperative computed tomographic scan. After fusion of preoperative and postoperative imaging, the accuracy for each electrode was calculated as the Euclidean distance between the planned and observed position of the electrode tip.
  
  
  RESULTS
  The median Euclidean distance between planned and observed electrode implantations was 3.5 mm (95% confidence interval, 2.9-3.9 mm) with a range of 1.2-13.7 mm.
  
  
  CONCLUSIONS
  In this study, we showed that the in vivo accuracy of our frameless stereotactic drilling technique, suitable for stereoelectroencephalography depth electrode placement and diagnostic brain biopsies, was 3.5 mm.
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands. Electronic address: n.verburg@vumc.nl.
authors.forename: Niels
authors.initials: N
authors.lastname: Verburg
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands.
authors.forename: Johannes C
authors.initials: JC
authors.lastname: Baayen
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Idema
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands.
authors.forename: Michiel A J
authors.initials: MA
authors.lastname: Klitsie
authors.affiliation: Department of Clinical Neurophysiology, Stichting Epilepsy Instellingen Nederland, Epilepsy Institutes in The Netherlands, SEIN, Heemstede, The Netherlands.
authors.forename: Steven
authors.initials: S
authors.lastname: Claus
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands.
authors.forename: Catharina S
authors.initials: CS
authors.lastname: de Jonge
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands.
authors.forename: W Peter
authors.initials: WP
authors.lastname: Vandertop
authors.affiliation: Neurosurgical Center Amsterdam, VU Medical Centre, Amsterdam, The Netherlands.
authors.forename: Philip C
authors.initials: PC
authors.lastname: de Witt Hamer
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy / Q000379:methods; D001921:Brain / Q000033:anatomy & histology / Q000601:surgery; D002648:Child; D000069279:Drug Resistant Epilepsy / Q000601:surgery; D004567:Electrodes, Implanted; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D059906:Neuroimaging; D038361:Neuronavigation; D019635:Neurosurgical Procedures / Q000379:methods; D015203:Reproducibility of Results; D013238:Stereotaxic Techniques; D055815:Young Adult
keywords: Depth electrode placement; Diagnostic biopsies; Frameless stereotaxy; Stereotactic drilling