Towards fully automated inner ear analysis with deep-learning-based joint segmentation and landmark detection framework

Abstract

Automated analysis of the inner ear anatomy in radiological data instead of time-consuming manual assessment is a worthwhile goal that could facilitate preoperative planning and clinical research. We propose a framework encompassing joint semantic segmentation of the inner ear and anatomical landmark detection of helicotrema, oval and round window. A fully automated pipeline with a single, dual-headed volumetric 3D U-Net was implemented, trained and evaluated using manually labeled in-house datasets from cadaveric specimen (N=43) and clinical practice (N=9). The model robustness was further evaluated on three independent open-source datasets (N = 23{} + 7{} + 17 scans) consisting of cadaveric specimen scans. For the in-house datasets, Dice scores of text{0.97 and 0.94}, intersection-over-union scores of text{0.94 and 0.89} and average Hausdorff distances of 0.065{} and 0.14{} voxel units were achieved. The landmark localization task was performed automatically with an average localization error of text{3.3 and 5.2} voxel units. A robust, albeit reduced performance could be attained for the catalogue of three open-source datasets. Results of the ablation studies with 43 mono-parametric variations of the basal architecture and training protocol provided task-optimal parameters for both categories. Ablation studies against single-task variants of the basal architecture showed a clear performance benefit of coupling landmark localization with segmentation and a dataset-dependent performance impact on segmentation ability.