Monocular Surface Reconstructions in Transcanal Endoscopic Ear Surgery: A Phantom Feasibility Study

OBJECTIVE: To evaluate whether a computer vision model can utilize monocular endoscopic images of the middle ear to generate three-dimensional (3D) surface reconstructions that register to ground-truth (GT) imaging with clinically acceptable accuracy for surgical navigation. METHODS: Eight temporal bone phantoms derived from the publicly available OpenEar data set were 3D-printed. Middle ear endoscopy was performed in each model using a standard monocular otologic endoscope, and a single endoscopic image captured of the mesotympanum. Images were processed with a monocular surface reconstruction model to generate predicted 3D surface reconstructions. Reconstructions were registered to GT meshes using natural anatomic landmarks. Surface reconstruction error (SRE) was quantified using the mean modified Hausdorff distance, and target registration error (TRE) was calculated using withheld test fiducials. RESULTS: Mean SRE across models was 0.58 ± 0.10 mm, with 81.6% of points within 1 mm of GT surfaces. Mean TRE was 0.96 ± 0.17 mm. CONCLUSION: Simple 2D, monocular endoscopic images can be converted into high-fidelity 3D surface reconstructions of middle ear anatomy, which can be registered to ground-truth imaging with submillimeter registration accuracy. These findings establish the preclinical feasibility of monocular, endoscope-centric navigation for transcanal endoscopic ear surgery.