title: The impact of workflow and volumetric feedback on frameless image-guided neurosurgery.
abstract: OBJECTIVE
  During image-guided neurosurgery, if the surgeon is not fully orientated to the surgical position, he or she will briefly shift attention toward the visualization interface of an image guidance station, receiving only momentary "point-in-space" information. The aim of this study was to develop a novel visual interface for neuronavigation during brain tumor surgery, enabling intraoperative feedback on the entire progress of surgery relative to the anatomy of the brain and its pathology, regardless of the interval at which the surgeon chooses to look.
  
  
  METHODS
  New software written in Java (Sun Microsystems, Inc., Santa Clara, CA) was developed to visualize the cumulative recorded instrument positions intraoperatively. This allowed surgeons to see all previous instrument positions during the elapsed surgery. This new interactive interface was then used in 17 frameless image-guided neurosurgical procedures. The purpose of the first 11 cases was to obtain clinical experience with this new interface. In these cases, workflow and volumetric feedback (WVF) were available at the surgeons' discretion (Protocol A). In the next 6 cases, WVF was provided only after a complete resection was claimed (Protocol B).
  
  
  RESULTS
  With the novel interactive interface, dynamics of surgical resection, displacement of cortical anatomy, and digitized functional data could be visualized intraoperatively. In the first group (Protocol A), surgeons expressed the view that WVF had affected their decision making and aided resection (10 of 11 cases). In 3 of 6 cases in the second group (Protocol B), tumor resections were extended after evaluation of WVF. By digitizing the cortical surface, an impression of the cortical shift could be acquired in all 17 cases. The maximal cortical shift measured 20 mm, but it typically varied between 0 and 10 mm.
  
  
  CONCLUSIONS
  Our first clinical results suggest that the embedding of WVF contributes to improvement of surgical awareness and tumor resection in image-guided neurosurgery in a swift and simple manner.
authors.affiliation: Department of Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands. p.a.woerdeman@neuro.azu.nl
authors.forename: Peter A
authors.initials: PA
authors.lastname: Woerdeman
authors.forename: Peter W A
authors.initials: PW
authors.lastname: Willems
authors.forename: Herke J
authors.initials: HJ
authors.lastname: Noordmans
authors.forename: Cornelis A F
authors.initials: CA
authors.lastname: Tulleken
authors.forename: Jan W B
authors.initials: JW
authors.lastname: van der Sprenkel
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery; D002540:Cerebral Cortex / Q000473:pathology / Q000601:surgery; D003658:Decision Making, Computer-Assisted; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D012984:Software; D025321:Surgery, Computer-Assisted / Q000379:methods*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014584:User-Computer Interface