title: Is the head position during preoperative image data acquisition essential for the accuracy of navigated brain tumor surgery?
abstract: OBJECTIVE
  To analyze the influence of head positioning during preoperative image data acquisition on intraoperative accuracy of modern neuronavigation systems.
  
  
  METHODS
  All measurements were performed preoperatively before opening the head. In 24 patients, preoperative MR image data acquisition was performed twice on a 0.5 T scanner using a contrast-enhanced T1-weighted sequence; first in the neutral head position, and thereafter in the surgical head position for pterional craniotomy. For both data sets, the Sylvian fissure, the central sulcus, and the superior and inferior temporal sulci were depicted on the patient's scalp using the frameless neuronavigation system EasyGuide Neurotrade mark. At the beginning of surgery, with the head fixed in a Mayfield clamp and an articulated instrument holder being used for fixation of the navigation system's pointer, the distances of 10 correlating points of the sulci for the two data sets were measured. To evaluate the accuracy of the navigation system in this experimental set-up, a phantom study was also performed.
  
  
  RESULTS
  The phantom study revealed a mean inaccuracy of 1.6 mm (range 0.1-2.3 mm, standard deviation 0.6 mm). The patient study revealed a mean inaccuracy of 1.8 mm (range 0.4-2.8 mm, standard deviation 0.5 mm).
  
  
  CONCLUSIONS
  The data suggest that the positioning of the patient's head during preoperative imaging plays no relevant role in intraoperative accuracy of neuronavigation. However, further studies and a larger number of patients with various pathologies in different regions of the brain are necessary to obtain a better understanding of the problem of brain shift in neuronavigation due to patient positioning alone, and to avoid procedure-related operative morbidity.
authors: Department of Neurosurgery, University of Technology (RWTH), Aachen, Germany. m.reinges@mail.com
authors: M H
authors: MH
authors: Reinges
authors: T
authors: T
authors: Krings
authors: H H
authors: HH
authors: Nguyen
authors: F J
authors: FJ
authors: Hans
authors: M C
authors: MC
authors: Korinth
authors: M
authors: M
authors: Höller
authors: W
authors: W
authors: Küker
authors: R
authors: R
authors: Thiex
authors: U
authors: U
authors: Spetzger
authors: J M
authors: JM
authors: Gilsbach
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000601:surgery*; D002138:Calibration; D003625:Data Collection; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation; D008279:Magnetic Resonance Imaging / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D012984:Software; D013238:Stereotaxic Techniques / Q000295:instrumentation; D014584:User-Computer Interface