title: Upgrade of an optical navigation system with a permanent electromagnetic position control: a first step towards "navigated control" for liver surgery.
abstract: BACKGROUND
  The main problems of navigation in liver surgery are organ movement and deformation. With a combination of direct optical and indirect electromagnetic tracking technology, visualisation and positional control of surgical instruments within three-dimensional ultrasound data and registration of organ movements can be realised simultaneously.
  
  
  METHODS
  Surgical instruments for liver resection were localised with an infrared-based navigation system (Polaris). Movements of the organ itself were registered using an electromagnetic navigation system (Aurora). The combination of these two navigation techniques and a new surgical navigation procedure focussed on a circumscribed critical dissection area were applied for the first time in liver resections.
  
  
  RESULTS
  This new technique was effectively implemented. The position of the surgical instrument was localised continuously. Repeated position control with observation of the navigation screen was not necessary. During surgical resection, a sonic warning signal was activated when the surgical instrument entered a "no touch" area--an area of reduced safety margin.
  
  
  CONCLUSIONS
  Optical tracking of surgical instruments and simultaneous electromagnetic registration of organ position is feasible in liver resection.
authors.affiliation: Surgery and Surgical Oncology, Charitè Universitätsmedizin Berlin, Experimental and Clinical Research Center, Berlin, Germany. siegfried.beller@krankenhaus-gmbh.de
authors.forename: Siegfried
authors.initials: S
authors.lastname: Beller
authors.forename: Sebastian
authors.initials: S
authors.lastname: Eulenstein
authors.forename: Thomas
authors.initials: T
authors.lastname: Lange
authors.forename: Michael
authors.initials: M
authors.lastname: Hünerbein
authors.forename: Peter M
authors.initials: PM
authors.lastname: Schlag
mesh_terms: D055590:Electromagnetic Phenomena; D004867:Equipment Design; D006498:Hepatectomy / Q000295:instrumentation*; D006801:Humans; D021621:Imaging, Three-Dimensional; D055096:Optical Devices; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D018084:Ultrasonography, Interventional / Q000295:instrumentation*