Sources of registration error with image guidance systems during endoscopic anterior cranial base surgery

OBJECTIVES: The goal of this study was to evaluate the accuracy of the registration process and to identity potential sources of error during anterior cranial base surgery. STUDY DESIGN AND SETTING: The registration accuracy of image guidance and the location of excluded fiducials were recorded prospectively from 50 endoscopic, anterior cranial base procedures in an academic university setting. RESULTS: The mean error of initial registration was 2.8 mm (range, 1.4 to 7.1 mm). Following the exclusion of fiducials the mean error of registration was 1.6 mm (range, 0.6 to 3.7 mm). There was a significant improvement in the mean error rate from initial to final registration following the exclusion of fiducials (P < 0.0001). Posterior fiducials were excluded most often and anterior fiducials were excluded the least. Registration accuracy was similar for CT and MRI (P = 0.64). CONCLUSIONS: The accuracy of the Stryker Image Guidance System is enhanced by the exclusion of individual fiducials with high registration errors. SIGNIFICANCE: The exclusion of fiducials with high registration errors increases the accuracy of image guidance in anterior cranial. base surgery.