HPFG: semi-supervised medical image segmentation framework based on hybrid pseudo-label and feature-guiding

Semi-supervised learning methods have been attracting much attention in medical image segmentation due to the lack of high-quality annotation. To cope with the noise problem of pseudo-label in semi-supervised medical image segmentation and the limitations of contrastive learning applications, we propose a semi-supervised medical image segmentation framework, HPFG, based on hybrid pseudo-label and feature-guiding, which consists of a hybrid pseudo-label strategy and two different feature-guiding modules. The hybrid pseudo-label strategy uses the CutMix operation and an auxiliary network to enable the labeled images to guide the unlabeled images to generate high-quality pseudo-label and reduce the impact of pseudo-label noise. In addition, a feature-guiding encoder module based on feature-level contrastive learning is designed to guide the encoder to mine useful local and global image features, thus effectively enhancing the feature extraction capability of the model. At the same time, a feature-guiding decoder module based on adaptive class-level contrastive learning is designed to guide the decoder in better extracting class information, achieving intra-class affinity and inter-class separation, and effectively alleviating the class imbalance problem in medical datasets. Extensive experimental results show that the segmentation performance of the HPFG framework proposed in this paper outperforms existing semi-supervised medical image segmentation methods on three public datasets: ACDC, LIDC, and ISIC. Code is available at https://github.com/fakerlove1/HPFG.