The accuracy of image-based safety analysis for robotic cochlear implantation.

PURPOSE: To evaluate the accuracy and reliability of image-based safety analysis for robotic cochlear implantation (RCI) in an ex vivo assessment. METHODS: The accuracy was evaluated in a study on 23 human temporal bones. For image analysis, a computer-assisted safety analysis based on intraoperative cone beam computed tomography was implemented. The method automatically segments the drill tunnel and predicts the distance between the tunnel and the facial nerve. In addition, the drilling error at the target is predicted. The predicted distances were compared with the actually drilled distances measured in postoperative high-resolution micro-computed tomography scans. The automatic method was compared to accuracies associated with a manual analysis of the image data. RESULTS: The presented computerized image-based analysis enabled the proximity of the facial nerve to the drill trajectory to be predicted with an accuracy of 0.22 ± 0.15 mm and drilling error at the target to be predicted with an accuracy of 0.11 mm ± 0.08 during N = 19 RCI procedures. The manual assessment of facial nerve proximity was performed with an accuracy of 0.34 ± 0.20 mm by a trained clinical expert. CONCLUSION: The assessment of intraoperative CT-based imaging presents multiple benefits over alternative safety mechanisms including early detection and applicability even in cases of malformation of the mastoid. This work presents a computer-assisted approach to image analysis that enables procedure safety measurements to be reliably performed with superior accuracy to other proposed safety methodologies, at a safe distance from the facial nerve. Its application must, however, be considered in relation to associated costs (time, cost, irradiation) and the dependence of the measure on a reliable preoperative segmentation.

Instrument flight to the inner ear.

Surgical robot systems can work beyond the limits of human perception, dexterity and scale making them inherently suitable for use in microsurgical procedures. However, despite extensive research, image-guided robotics applications for microsurgery have seen limited introduction into clinical care to date. Among others, challenges are geometric scale and haptic resolution at which the surgeon cannot sufficiently control a device outside the range of human faculties. Mechanisms are required to ascertain redundant control on process variables that ensure safety of the device, much like instrument-flight in avionics. Cochlear implantation surgery is a microsurgical procedure, in which specific tasks are at sub-millimetric scale and exceed reliable visuo-tactile feedback. Cochlear implantation is subject to intra- and inter-operative variations, leading to potentially inconsistent clinical and audiological outcomes for patients. The concept of robotic cochlear implantation aims to increase consistency of surgical outcomes such as preservation of residual hearing and reduce invasiveness of the procedure. We report successful image-guided, robotic CI in human. The robotic treatment model encompasses: computer-assisted surgery planning, precision stereotactic image-guidance, in-situ assessment of tissue properties and multipolar neuromonitoring (NM), all based on in vitro, in vivo and pilot data. The model is expandable to integrate additional robotic functionalities such as cochlear access and electrode insertion. Our results demonstrate the feasibility and possibilities of using robotic technology for microsurgery on the lateral skull base. It has the potential for benefit in other microsurgical domains for which there is no task-oriented, robotic technology available at present.