用自适应加权机制提升少样本医学图像分割精度
Scale-aware Adaptive Supervised Network with Limited Medical Annotations
- 双分支结构融合高低层特征,动态调整预测权重
- 在仅10%标注数据下分割性能接近全监督水平
- 适合标注稀缺的医学图像分析场景
医学图像分割在半监督学习中面临严重标注稀缺问题,需专家放射学知识,且不同视角和经验水平导致标注差异大,复杂解剖结构的边界精确定位也因多尺度特征融合不足而受限。现有半监督方法相比全监督表现显著下降,尤其在小目标分割和边界细化任务中。为此,我们提出SASNet(Scale-aware Adaptive Supervised Network),一种双分支架构,通过新颖的尺度感知自适应重加权机制,融合低层与高层特征表示。方法创新包括:1)利用时间置信度累积动态加权像素级预测;2)通过3D傅里叶域变换模拟标注变异性;3)基于符号距离图算法实现分割-回归一致性学习以增强边界精度。三者结合,在统一优化框架中融入空间、时间与几何一致性。在LA、Pancreas-CT和BraTS数据集上的全面评估表明,SASNet在仅使用少量标注数据时表现优异,超越当前最优半监督方法,并逼近全监督性能。代码已开源:https://github.com/HUANGLIZI/SASNet。
原文摘要 · Abstract (English)
Medical image segmentation faces critical challenges in semi-supervised learning scenarios due to severe annotation scarcity requiring expert radiological knowledge, significant inter-annotator variability across different viewpoints and expertise levels, and inadequate multi-scale feature integration for precise boundary delineation in complex anatomical structures. Existing semi-supervised methods demonstrate substantial performance degradation compared to fully supervised approaches, particularly in small target segmentation and boundary refinement tasks. To address these fundamental challenges, we propose SASNet (Scale-aware Adaptive Supervised Network), a dual-branch architecture that leverages both low-level and high-level feature representations through novel scale-aware adaptive reweight mechanisms. Our approach introduces three key methodological innovations, including the Scale-aware Adaptive Reweight strategy that dynamically weights pixel-wise predictions using temporal confidence accumulation, the View Variance Enhancement mechanism employing 3D Fourier domain transformations to simulate annotation variability, and segmentation-regression consistency learning through signed distance map algorithms for enhanced boundary precision. These innovations collectively address the core limitations of existing semi-supervised approaches by integrating spatial, temporal, and geometric consistency principles within a unified optimization framework. Comprehensive evaluation across LA, Pancreas-CT, and BraTS datasets demonstrates that SASNet achieves superior performance with limited labeled data, surpassing state-of-the-art semi-supervised methods while approaching fully supervised performance levels. The source code for SASNet is available at https://github.com/HUANGLIZI/SASNet.
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