Cross-Domain Few-Shot Learning for Rare-Disease Skin Lesion Segmentation.

Recently, deep learning (DL)-based skin lesion segmentation in dermoscopic images has advanced the efficient diagnosis of skin diseases. Commonly, most of the DL-based methods require a large amount of training data and can only perform accurate predictions on pre-defined classes. However, there exist some rare skin diseases with very limited labeled samples, which poses great challenges to typical DL-based methods. Few-shot learning (FSL) technique, which aims to train models with abundant seen classes and then generalizes to related unseen classes, is promising in addressing a similar problem. Unfortunately, simply borrowing the typical FSL is infeasible since collecting such abundant seen-class data (common skin diseases), is also difficult. In this paper, we propose a cross-domain few-shot segmentation (CD-FSS) framework, which enables the model to leverage the learning ability obtained from the natural domain, to facilitate rare-disease skin lesion segmentation with limited data of common diseases. Specifically, the framework consists of two processes, i.e., specific learning and generic learning, which are alternately optimized in a meta-training manner. A specific learner and a generic learner are tailored to build relationships between both processes. Experimental results demonstrate that our framework significantly improves the generalization ability from natural domain to unseen medical domain.