Navigated Surgery at the Lateral Skull Base and Registration and Preoperative Imagery Experimental Results

Objectives: To assess factors that affect the accuracy of navigated surgery at the human lateral skull base, including the choice of registration procedures and preoperative computed tomography (CT) section thickness, and to compare target registration error, a measure of clinical application accuracy, with root mean square, an accuracy variable provided by several surgical navigation systems. Design: Experimental cadaver study. Setting: Medical university. Participants: Anatomic specimen. Main Outcome Measures: Target registration error. Results: A combination of high-resolution CT images, 0.5-mm section thickness, with pair-point matching of a combination of markers on the anatomical specimen, and the registration element was found to be superior (mean [SD], 0.72 [0.28] mm). No correlation was found between target registration error and root mean square. A statistical analysis that considers image registration and acquisition method did not show any correlation between target registration error and root mean square error (r=-0.175, P=.15). Conclusions: High-resolution CT images, 0.5 mm, of the petrous bone and a pair-point registration using loci on the patient and registration superstructures worked best under experimental conditions. Only target registration error was found to provide reliable information on accuracy intraoperatively. In line with the literature, these data prove that root mean square bears little relevance for clinical application accuracy.