Leveraging Textual Anatomical Knowledge for Class-Imbalanced Semi-Supervised Multi-Organ Segmentation

Imbalanced class distributions among different organs pose significant challenges in real-world semi-supervised multi-organ segmentation. Integrating anatomical priors offers a promising research direction to mitigate these imbalances. In this paper, we explore the capabilities of Multimodal Large Language Models (MLLM) to extract robust, generic textual anatomical insights serving as prior knowledge for segmentation model. Specifically, we employ GPT-4o to generate detailed textual descriptions of anatomical priors-including both inter-organ relative positional relationships and organ shape characteristics. These priors generated only once for the whole training and testing are then seamlessly integrated into the segmentation model as parameters within the segmentation head. Furthermore, we align the textual priors with visual features using contrastive learning. The inter-organ positional priors guide the model in localizing smaller organs relative to larger ones, while the organ shape priors help ensure that the learned morphological structures are more anatomically plausible. Extensive experiments demonstrate that our method significantly outperforms some state-of-the-art approaches. The source code is available at: https://github.com/Lunn88/TAK-Semi.