Accuracy of Video Optical See-Through Augmented Reality Surgical System (VOSTARS) to Guide Craniotomy: A Phantom and a Human Cadaver Study

Abstract

Background: Augmented reality (AR) may support neuronavigation by displaying patient-specific anatomical information and surgical plans directly within the surgeon’s view of the operative field. Reliable registration between virtual content and patient anatomy remains a critical requirement. Patient-specific templates offer a non-invasive registration strategy, but positioning errors at the facial support may propagate to the surgical target. Methods: We performed a preclinical feasibility evaluation of the Video and Optical See-Through Augmented Reality Surgical System (VOSTARS), a head-mounted AR platform for surgical navigation, using patient-specific template-based registration. Six craniotomies were planned using CT datasets from two fresh-frozen human cadaver heads and two corresponding cranial phantoms were generated from the same datasets. Visualization accuracy, reported as target visualization error (TVE3D), and trajectory-tracing performance were first assessed on the phantoms. The complete AR-guided planning-to-execution workflow was subsequently evaluated on the corresponding cadaveric specimens by assessing containment of the AR-traced craniotomy trajectories within patient-specific inspection windows corresponding to a tolerance of ±1.5 mm. Results: In the phantom experiments, the mean TVE3D calculated across five of the six planned craniotomies was 1.64 mm, with individual mean values ranging from 1.33 to 1.91 mm. Craniotomy 1 had a mean TVE3D of 6.92 mm; the higher error was attributed to incorrect phantom assembly. Four of the six craniotomy trajectories traced on the phantoms under AR guidance showed complete overlap with the corresponding virtual trajectories. For the other two, trajectory overlap was 62.5% and 67.0%, with a mean deviation from the planned trajectory of 0.79 mm in both cases. In the cadaveric experiments, the complete AR-guided planning-to-execution workflow was completed for all six planned craniotomies. Two of the six AR-traced craniotomy trajectories were completely contained within the inspection windows corresponding to the predefined ±1.5-mm tolerance. Of the remaining four trajectories, two were partially contained, one was minimally contained and one was not contained within the inspection window. Conclusions: This study supports the technical feasibility of a patient-specific AR workflow for craniotomy guidance across anatomically different cranial approaches. In this exploratory preclinical study, VOSTARS enabled the translation of patient-specific preoperative planning directly to the operative field and provided AR guidance during the initial stages of cranial surgery. The cadaveric findings also highlight template fit and positioning as important determinants of workflow performance. Further quantitative and comparative validation is required before clinical implementation.