UTriGate-Net : Uncertainty-aware brain tumor segmentation via triaxial context encoding and gated modality fusion
Tongxue Zhou, Su Ruan, Yanda Meng, Jinming Duan, Haigen Hu, Bingbing Jiang, Zhiwei Ji, Bangli Liu, Tingjin Luo, Baiying Lei · Expert Systems with Applications · 2026
Accurate segmentation of brain tumors from multi-modal MRI is crucial for diagnosis and treatment planning. However, challenges such as severe class imbalance, modality-specific feature heterogeneity, and predictive uncertainty hinder reliable performance. In this work, we propose UTriGate-Net, a novel uncertainty-aware multi-modal brain tumor segmentation framework. First, we design a Triaxial Context Encoding (TCE) block that extracts anisotropic spatial features by applying directional convolutions along the axial, coronal, and sagittal planes, thereby enhancing 3D contextual representation. Second, we introduce a Gated Modality Fusion (GMF) module, which adaptively integrates complementary information across modalities through modality-specific gating weights that suppress redundancy while retaining salient features. Finally, to improve segmentation reliability, we develop an Uncertainty-Regularized Weighted Loss (URWL) that combines dynamic class-specific weighting to mitigate class imbalance with an entropy-based uncertainty penalty to encourage well-calibrated predictions. Experiments on the BraTS 2019 and 2020 datasets demonstrate that UTriGate-Net achieves superior segmentation accuracy and robustness, particularly in challenging subregions. Overall, the proposed framework offers a promising solution for reliable and precise brain tumor delineation in clinical practice.