title: Accuracy of magnetic resonance imaging-directed frame-based stereotaxis.
abstract: BACKGROUND
  Accurate placement of a probe to the deep regions of the brain is an important part of neurosurgery. In the modern era, magnetic resonance image (MRI)-based target planning with frame-based stereotaxis is the most common technique.
  
  
  OBJECTIVE
  To quantify the inaccuracy in MRI-guided frame-based stereotaxis and to assess the relative contributions of frame movements and MRI distortion.
  
  
  METHODS
  The MRI-directed implantable guide-tube technique was used to place carbothane stylettes before implantation of the deep brain stimulation electrodes. The coordinates of target, dural entry point, and other brain landmarks were compared between preoperative and intraoperative MRIs to determine the inaccuracy.
  
  
  RESULTS
  The mean 3-dimensional inaccuracy of the stylette at the target was 1.8 mm (95% confidence interval [CI], 1.5-2.1. In deep brain stimulation surgery, the accuracy in the x and y (axial) planes is important; the mean axial inaccuracy was 1.4 mm (95% CI, 1.1-1.8). The maximal mean deviation of the head frame compared with brain over 24.1 ± 1.8 hours was 0.9 mm (95% CI, 0.5-1.1). The mean 3-dimensional inaccuracy of the dural entry point of the stylette was 1.8 mm (95% CI, 1.5-2.1), which is identical to that of the target.
  
  
  CONCLUSIONS
  Stylette positions did deviate from the plan, albeit by 1.4 mm in the axial plane and 1.8 mm in 3-dimensional space. There was no difference between the accuracies at the dura and the target approximately 70 mm deep in the brain, suggesting potential feasibility for accurate planning along the whole trajectory.
authors.affiliation: West Australian Neurosurgical Service, Sir Charles Gairdner Hospital, Perth, Australia.
authors.forename: Nova B
authors.initials: NB
authors.lastname: Thani
authors.forename: Arul
authors.initials: A
authors.lastname: Bala
authors.forename: Christopher R P
authors.initials: CR
authors.lastname: Lind
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000601:surgery*; D046690:Deep Brain Stimulation / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D004567:Electrodes, Implanted / Q000592:standards; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods / Q000592:standards*; D011300:Preoperative Care / Q000295:instrumentation / Q000379:methods / Q000592:standards; D013238:Stereotaxic Techniques / Q000592:standards*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods / Q000592:standards*