Noninvasive Registration Strategies and Advanced Image Guidance Technology for Submillimeter Surgical Navigation Accuracy in the Lateral Skull Base

Hypothesis: Combining novel registration strategies and advanced image guidance technology enable submillimeter accurate and noninvasive navigation for middle ear and lateral skull base surgery. Background: Surgery in the internal auditory canal and the petrous apex present a cognitive and motoric challenge for the surgeon. To date, image guidance rarely assists these procedures, mainly due to the lack of navigation solutions providing submillimeter accuracy associated with low cost in terms of invasiveness, radiation, and time. Methods: This study proposes an approach to clinically viable image guidance by using a combination of advanced image guidance technology and noninvasive registration strategies. Based on accuracy-optimized optical tracking hardware (accuracy: 0.05 ± 0.025 mm), 14 novel registration strategies were investigated. In human cadaveric temporal bone specimens n = 36 registration attempts per strategy were conducted. Target registration errors at 10 anatomical targets were measured. Results: The most accurate registration strategies were identified as paired-point-matching using eight landmarks located in the external auditory canal and middle ear and surface matching using combined surfaces of the middle ear, the external auditory canal and the mastoid cortex yielding target registration errors of 0.51 ± 0.28 mm and 0.36 ± 0.13 mm respectively. Conclusions: This study demonstrates submillimeter TREs achieved with noninvasive, anatomy-based registration strategies in combination with advanced image guidance technology. Clinically viable LSB and ME navigation is realized without additional invasiveness, radiation and time associated with artificial fiducials. The appropriate registration strategy can be chosen by the surgeon depending on the pathology and surgical approach.