title: Evaluation of a 3-dimensional voxel-based neuronavigation system with perspective image rendering for keyhole approaches to the skull base: an anatomical study.
abstract: BACKGROUND
  Keeping track of the endoscope tip in 3 planes (axial, coronal, and sagittal) while performing skull base surgeries can be difficult because the surgeon is focused most on the live video images of the endoscope. For that reason, it was the aim of this anatomical cadaver study to evaluate the usefulness of a voxel-based neuronavigation system with 3-dimensional (3D) perspective image rendering for endoscopic procedures through keyhole approaches to the skull base.
  
  
  METHODS
  On 5 whole-body fixed cadavers, frontolateral and retrosigmoid approaches were performed bilaterally using a neuronavigation system with 3D perspective image rendering (Cbyon, Med-Surgical Services Inc., Sunnyvale, California). Target points defined on the selected target structures were approached with the navigated ∅ 4-mm 0° endoscope (Storz, Tuttlingen, Germany). Using an Endocameleon 4-mm rigid endoscope capable of changing its angle of view while remaining stationary, the surgical field was checked for injuries before and after insertion of the navigated 0° endoscope.
  
  
  RESULTS
  The median neuronavigation registration error was 0.95 mm (range 0.6 to 1.2 mm). Evaluation showed that 100% of the defined targets were reached and visualized. Neither a target structure nor neurovascular structures or surrounding brain tissue were injured by the navigated 0° endoscope.
  
  
  CONCLUSIONS
  A neuronavigation system with 3D voxel-based perspective image rendering could potentially improve safety during complex skull base surgeries, and possibly also help to improve surgical results. Such a system, however, cannot replace a neurosurgeon's experience nor surgical skill or anatomical knowledge. It is an excellent teaching tool for young neurosurgeons, but it also has some limitations. Therefore, clinical studies will be necessary to further evaluate the benefits of this type of neuronavigation system in a clinical setting.
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany. Electronic address: guenther.feigl@web.de.
authors.forename: Guenther C
authors.initials: GC
authors.lastname: Feigl
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Krischek
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Ritz
authors.affiliation: Department of Neurosurgery, Katharinenhospital Stuttgart, Stuttgart, Germany.
authors.forename: Firas
authors.initials: F
authors.lastname: Thaher
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Jakob S
authors.initials: JS
authors.lastname: Marquardt
authors.affiliation: Institute of Anatomy, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hirt
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Korn
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schumann
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Marcos
authors.initials: M
authors.lastname: Tatagiba
authors.affiliation: Department of Neurosurgery, University Hospital Tuebingen, Eberhard-Karls-University, Tuebingen, Germany.
authors.forename: Florian H
authors.initials: FH
authors.lastname: Ebner
mesh_terms: D059925:Anatomic Landmarks; D001921:Brain / Q000033:anatomy & histology / Q000601:surgery; D002102:Cadaver; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging; D044583:Neuroendoscopy / Q000379:methods*; D038361:Neuronavigation / Q000379:methods*; D019291:Skull Base / Q000033:anatomy & histology* / Q000601:surgery*
keywords: 3D neuronavigation; Keyhole approach; Neuroendoscopy; Skull base