An in situ non-contact 3D microscopic measurement system for temporal bone anatomy based on stereo imaging

Accurate quantitative assessment of temporal bone microanatomy is essential for otologic research and surgical planning. However, existing measurement approaches, including manual tools, ex vivo microscopy, and high-resolution computed tomography, are limited by contact requirements, indirect measurement, insufficient spatial resolution, or the inability to provide efficient quantitative feedback under microscopic visualization. To address these limitations, this study developed an in situ, non-contact three-dimensional (3D) microscopic measurement system for temporal bone anatomy based on stereo imaging. The system integrates microscopic stereo calibration, deep learning-based disparity estimation, 3D reconstruction, and an interactive measurement workflow. Reconstruction accuracy was evaluated using a high-precision scanned LEGO model, while measurement accuracy was validated using a custom-designed 3D-printed module with known geometric dimensions. The feasibility of the system was further demonstrated through measurements of representative anatomical structures in four temporal bones from two fresh-frozen cadaver heads. The results showed that the root mean square error of 3D reconstruction was 0.05-0.13 mm. For geometric measurements, the average error was below 1.7%, with a maximum error below 4.0% across multiple metrics. The system enabled in situ, non-contact measurement of various anatomical parameters under microscopic conditions. These findings indicate that the proposed system provides accurate and reliable quantitative 3D measurement of temporal bone microstructures. As a technical prototype, it provides a practical tool for anatomical research and supports future development toward intraoperative, non-contact, in situ quantitative assessment in otomicrosurgery.