CTI-Unet: Cascaded Threshold Integration for Improved U-Net Segmentation of Pathology Images
Mingyang Zhu, Yuqiu Liang, Jiacheng Wang
TL;DR
CTI-Unet addresses threshold sensitivity in histopathology segmentation by cascading multi-threshold outputs within a two-stage U-Net framework. The Initial Segmentation Network (Model 1) generates preliminary masks, while the Threshold Integration Network (Model 2) fuses outputs from thresholds such as $0.01$, $0.1$, and $0.6$ along with the grayscale image to refine predictions. Training uses a composite loss $\mathcal{L} = \mathcal{L}_{\text{Tversky}}(\alpha_i,\beta_i) + 0.5\times \mathcal{L}_{\text{CE}}$, with normalization, resizing to $2048\times2048$, and MONAI-based augmentation, evaluated on the KPI2024 PAS-stained KPI dataset, where CTI-Unet outperforms nnU-Net, Swin-Unet, and CE-Net with an overall Dice score of $91.64\%$. Qualitative results show reduced noise and smoother boundaries thanks to the Threshold Integration Network, evidencing improved robustness and detail preservation in kidney pathology segmentation. The approach offers a flexible framework that can be extended with attention or transformer components and applied to other challenging histology segmentation tasks.
Abstract
Chronic kidney disease (CKD) is a growing global health concern, necessitating precise and efficient image analysis to aid diagnosis and treatment planning. Automated segmentation of kidney pathology images plays a central role in facilitating clinical workflows, yet conventional segmentation models often require delicate threshold tuning. This paper proposes a novel \textit{Cascaded Threshold-Integrated U-Net (CTI-Unet)} to overcome the limitations of single-threshold segmentation. By sequentially integrating multiple thresholded outputs, our approach can reconcile noise suppression with the preservation of finer structural details. Experiments on the challenging KPIs2024 dataset demonstrate that CTI-Unet outperforms state-of-the-art architectures such as nnU-Net, Swin-Unet, and CE-Net, offering a robust and flexible framework for kidney pathology image segmentation.
