The volume-wise labeling of 3D medical images is expertise-demanded and time-consuming; hence semi-supervised learning (SSL) is highly desirable for training with limited labeled data. Imbalanced class distribution is a severe problem that bottlenecks the real-world application of these methods but was not addressed much. Aiming to solve this issue, we present a novel Dual-debiased Heterogeneous Co-training (DHC) framework for semi-supervised 3D medical image segmentation. Specifically, we propose two loss weighting strategies, namely Distribution-aware Debiased Weighting (DistDW) and Difficulty-aware Debiased Weighting (DiffDW), which leverage the pseudo labels dynamically to guide the model to solve data and learning biases. The framework improves significantly by co-training these two diverse and accurate sub-models. We also introduce more representative benchmarks for class-imbalanced semi-supervised medical image segmentation, which can fully demonstrate the efficacy of the class-imbalance designs. Experiments show that our proposed framework brings significant improvements by using pseudo labels for debiasing and alleviating the class imbalance problem. More importantly, our method outperforms the state-of-the-art SSL methods, demonstrating the potential of our framework for the more challenging SSL setting. Code and models are available at: https://github.com/xmed-lab/DHC.

提出一种新颖的双消除偏见异构协同（DHC）框架，用于半监督3D医学图像分割，该框架通过两种损失加权策略（DistDW和DiffDW）动态利用伪标签引导模型解决数据和学习偏差，并且通过协同训练两个准确的子模型显著提高，实验结果表明我们的方法克服了类别不平衡问题，优于当前的半监督学习方法，在更具挑战性的半监督设置中显示出潜力。

DHC: 双修正异构协同训练框架用于类别不平衡的半监督医学图像分割