title: Frameless stereotactic targeting devices: technical features, targeting errors and clinical results.
abstract: BACKGROUND
  Brain biopsies (BB) and depth electrode placements (DEP) are increasingly performed using frameless stereotactic targeting devices. This paper is intended to provide a comprehensive review of the technical features, targeting errors and clinical results.
  
  
  METHODS
  A PubMed literature search from 1995-2010 was performed.
  
  
  RESULTS
  (A) Modified stereotactic arcs, (B) arm-based devices with and without aiming facilities, and (C) skull affixed devices were found. Guidance technologies were navigation systems (all groups), prospective stereotaxy and custom designed platforms (group C). Mean total errors ranged between 4.4 and 5.4 mm for BB and 2.0 and 3.2 mm for DEP. Diagnostic yield of BB was 89-100%. The clinical success rate for DEP was 96-100%.
  
  
  CONCLUSIONS
  Frameless stereotactic targeting devices may reach targeting errors and clinical results comparable with standard frame-based stereotaxy. Advantages and disadvantages of different devices should be acknowledged to ensure optimal technical performance.
authors.affiliation: Medical University of Innsbruck, SIP-Department for Microinvasive Therapy, Department of Radiology, Austria. gerlig.widmann@i-med.ac.at
authors.forename: Gerlig
authors.initials: G
authors.lastname: Widmann
authors.forename: Peter
authors.initials: P
authors.lastname: Schullian
authors.forename: Martin
authors.initials: M
authors.lastname: Ortler
authors.forename: Reto
authors.initials: R
authors.lastname: Bale
mesh_terms: D001706:Biopsy / Q000379:methods; D001921:Brain / Q000473:pathology*; D006801:Humans; D019300:Medical Errors; D038361:Neuronavigation / Q000295:instrumentation* / Q000379:methods*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012371:Robotics; D013238:Stereotaxic Techniques / Q000295:instrumentation*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation