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A Multi-Scale Inception-UNet with Structure-Aware Evaluation for Branch-Preserving Segmentation of Organoids
Proceedings of The 9th International Conference on Medical Imaging with Deep Learning, PMLR 315:4071-4084, 2026.
Abstract
Branched organoids exhibit increasingly complex morphologies as they progress from simple spheroid states to highly ramified structures, making topology-preserving segmentation essential for quantitative biological analysis. Capturing thin protrusions and maintaining branch continuity remains challenging for classical UNet-based architectures, particularly in brightfield imaging where fine structures are easily blurred or disconnected. In this work, we present a multi-scale Inception-UNet designed to capture the heterogeneous spatial scales of branched organoids through parallel convolutional paths with complementary receptive fields. As a model system, we analyze brightfield pancreatic ductal adenocarcinoma (PDAC) organoids, a system known for strong morphological heterogeneity and invasive branching behavior randriamanantsoa2022pdacOrganoids, cultured using high-throughput Patternoid assays kurzbach2025patternoid that enable standardized imaging and robust quantitative analysis. To assess segmentation quality beyond region overlap, we combine Dice with the structure-aware clDice metric that directly probes branch integrity and topological continuity. Across deterministic seeds and strictly separated organoid positions, the Inception-UNet achieves the highest region-based Dice ($0.868 \pm 0.062$) and clDice ($0.545 \pm 0.123$), and most importantly, the strongest preservation of branch continuity compared to UNet and UNet++. These improvements become increasingly pronounced with growing morphological complexity. Overall, our results demonstrate that multi-scale feature extraction combined with topology-aware evaluation substantially improves segmentation of branched organoids and provides a robust foundation for downstream morphological and invasion-related analyses.