Introduction: 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.
Conclusion: Optical tracking of surgical instruments and simultaneous electromagnetic registration of organ position is feasible in liver resection.