Optical and electromagnetic tracking for navigated surgery of the sinuses and frontal skull base.

BACKGROUND New hardware and software algorithms in electromagnetic tracking for computer assisted surgery (CAS) have been developed. We aimed to compare electromagnetic tracking for navigated procedures in frontal skull base surgery to optical tracking. METHODS Target registration error (TRE) was determined in 6 anatomic specimens in an experimental wet-lab. As targets, 6 titanium screws were evenly distributed over the surgical areas of interest from the frontal sinus to the clivus. Optical tracking and electromagnetic tracking was evaluated in identical software environment using a last generation commercially available navigation system. RESULTS Submillimetric application accuracy could be achieved with both tracking modalities. Optical was more accurate than electromagnetic tracking and its reliability was better. Target position did not influence TRE, however TRE varied significantly from skull to skull. CONCLUSIONS Although less accurate than optical tracking, electromagnetic tracking still offers excellent accuracy and reliability for anterior skull base surgery. Electromagnetic tracking is not dependent on direct line of sight between its hardware components and therefore easily integrated even in cluttered operating theatres.