title: An advanced navigation protocol for endoscopic transsphenoidal surgery.
abstract: OBJECTIVE
  To report our clinical experience with an advanced navigation protocol that provides seamless integration into the operating workflow of endoscopic transsphenoidal surgery.
  
  
  METHODS
  From 32 consecutive cases of endoscopic transsphenoidal surgery, an optimal setup of continuous electromagnetic instrument navigation was created. Additionally, our standard multimodality image navigation of T1-weighted magnetic resonance (MR) images for soft tissue, MR angiogram for vascular structures, and computed tomography (CT) for solid bone was advanced by the addition of a CT surface rendering for fine paranasal sinus structures. The anatomic structures visualized and their clinical impacts were compared between standard and advanced visualization protocol. Bone-windowed CT images served as reference. The accuracy of the navigation setup was assessed by intraoperative landmark tests. Potential tissue shift was calculated by comparing pre- and postoperative MR angiograms of 20 macroadenomas.
  
  
  RESULTS
  After a learning curve of 2 cases (1 ferromagnetic interference and 1 dislocation of the patient reference tracker), the advanced navigation protocol was feasible in 30 cases. Advanced multimodality imaging was able to visualize significantly finer paranasal sinus structures than multimodality image navigation without CT surface rendering, equal to bone-windowed CT images (P < 0.001, McNemar test). This was found helpful for orientation in cases of complex sphenoid sinus anatomy. The accuracy of the advanced navigation setup corresponded to standard optic navigation with skull fixation. A tissue shift of median 2 mm (range 0-9 mm) was observed in the posterior genu of the internal carotid arteries after tumor resection.
  
  
  CONCLUSIONS
  The advanced navigation protocol permits continuous suction-tracked navigation guidance during endoscopic transsphenoidal surgery and optimal visualization of solid bone, fine paranasal sinus structures, soft-tissue and vascular structures. This may add to the safety of the procedure especially in cases of anatomical variations and in cases of recurrent adenomas with distorted anatomy.
authors.affiliation: Department of Neurosurgery, Medical University Vienna, Austria.
authors.forename: Ayguel
authors.initials: A
authors.lastname: Mert
authors.affiliation: Department of Neurosurgery, Medical University Vienna, Austria.
authors.forename: Alexander
authors.initials: A
authors.lastname: Micko
authors.affiliation: Department of Neurosurgery, Medical University Vienna, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Donat
authors.affiliation: Department of Neurosurgery, Medical University Vienna, Austria.
authors.forename: Manuela
authors.initials: M
authors.lastname: Maringer
authors.affiliation: VRVis Research Centre for Virtual Reality and Visualization GmbH, Vienna, Austria.
authors.forename: Katja
authors.initials: K
authors.lastname: Buehler
authors.affiliation: Department of Clinical Neurosciences, Division of Neurosurgery, University of Calgary, Canada.
authors.forename: Garnette R
authors.initials: GR
authors.lastname: Sutherland
authors.affiliation: Department of Neurosurgery, Medical University Vienna, Austria.
authors.forename: Engelbert
authors.initials: E
authors.lastname: Knosp
authors.affiliation: Department of Neurosurgery, Medical University Vienna, Austria; Department of Clinical Neurosciences, Division of Neurosurgery, University of Calgary, Canada. Electronic address: stefan.wolfsberger@meduniwien.ac.at.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wolfsberger
mesh_terms: D002985:Clinical Protocols; D004724:Endoscopy / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D064847:Multimodal Imaging; D038361:Neuronavigation / Q000295:instrumentation / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods*; D015203:Reproducibility of Results; D013100:Sphenoid Bone / Q000601:surgery*; D014057:Tomography, X-Ray Computed
keywords: Accuracy; Endoscopy; Multimodality navigation; Transsphenoidal pituitary surgery