title: VarioGuide: a new frameless image-guided stereotactic system--accuracy study and clinical assessment.
abstract: OBJECTIVE
  VarioGuide (BrainLAB AG, Feldkirchen, Germany) is a new system for frameless image-guided stereotaxy. In the present study, we aimed to assess target point accuracy in a laboratory setting and the clinical feasibility of the system.
  
  
  METHODS
  Using the phantom of our frame-based stereotactic system (Riechert-Mundinger; Inomed Medizintechnik GmbH, Teningen, Germany), target points were approached from different angles with the frameless system. Target point deviation in the x, y, and z planes was assessed. Furthermore, patients harboring intracranial lesions were diagnostically biopsied using VarioGuide.
  
  
  RESULTS
  Phantom-based accuracy measurements yielded a mean target point deviation of 0.7 mm. Between February 2007 and April 2008, 27 patients were diagnostically biopsied. Lesion volumes ranged from 0.2 to 117.6 cm3, trajectory length ranged from 25.3 to 64.1 mm, and the diagnostic yield was 93%.
  
  
  CONCLUSIONS
  Concluding from the phantom measurements with ideal image-object registration, assumed spherical lesions with a volume of 0.524 cm can be biopsied with 100% target localization. Early clinical data revealed VarioGuide to be safe and accurate for lesions of 0.2 cm3 and larger. Thereby, the system seems feasible for the biopsy of most intracranial lesions.
authors.affiliation: Department of Neurosurgery, Technical University of Munich, Munich, Germany. florian.ringel@lrz.tum.de
authors.forename: Florian
authors.initials: F
authors.lastname: Ringel
authors.forename: Dominik
authors.initials: D
authors.lastname: Ingerl
authors.forename: Stephanie
authors.initials: S
authors.lastname: Ott
authors.forename: Bernhard
authors.initials: B
authors.lastname: Meyer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000295:instrumentation / Q000379:methods; D001921:Brain / Q000033:anatomy & histology / Q000473:pathology / Q000601:surgery*; D003399:Craniotomy / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007431:Intraoperative Complications / Q000517:prevention & control; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000295:instrumentation* / Q000379:methods*; D019635:Neurosurgical Procedures / Q000295:instrumentation* / Q000379:methods*; D011446:Prospective Studies; D012984:Software; D012986:Software Validation; D055815:Young Adult