The automated diagnosis of rare skin diseases using dermoscopy images, known as a few-shot learning (FSL) problem, remains challenging, since traditional FSL research tends to disregard the intrinsic hierarchical nature of rare diseases and data uncertainty. To address these issues, we propose to conduct rare skin disease diagnosis in hyperbolic space, which facilitates implicit class hierarchical structures and precise uncertainty measurement due to pivotal geometrical properties. We propose a Hyperbolic Geometry-driven Robustness Enhancement (HGRE) framework specifically tailored for diagnosing rare skin diseases. The HGRE framework uses implicit hierarchical relation in the hyperbolic space to better represent the features of rare diseases. Moreover, the framework incorporates an Adversarial Proxy Construction (APC) module to address the problem of data uncertainty. Specifically, the APC module uses the distance to the hyperbolic space origin as an indicator of uncertainty to filter and construct adversarial proxies for each uncertain prototype to achieve adversarial robust training. Leveraging the two unique geometrical properties, our HGRE framework effectively addresses the limitations of insufficient hierarchical relation utilization and data uncertainty in FSL-based rare skin disease diagnosis. This enhancement of the model's robustness in training has been corroborated by extensive empirical validation on two skin lesion datasets, where HGRE's performance notably surpassed existing state-of-the-art FSL methods.

The computer-aided diagnosis (CAD) for rare diseases using medical imaging poses a significant challenge due to the requirement of large volumes of labeled training data, which is particularly difficult to collect for rare diseases. Although Few-shot learning (FSL) methods have been developed for this task, these methods focus solely on rare disease diagnosis, failing to preserve the performance in common disease diagnosis. To address this issue, we propose the Disentangle then Calibrate with Gradient Guidance (DCGG) framework under the setting of generalized few-shot learning, i.e., using one model to diagnose both common and rare diseases. The DCGG framework consists of a network backbone, a gradient-guided network disentanglement (GND) module, and a gradient-induced feature calibration (GFC) module. The GND module disentangles the network into a disease-shared component and a disease-specific component based on gradient guidance, and devises independent optimization strategies for both components, respectively, when learning from rare diseases. The GFC module transfers only the disease-shared channels of common-disease features to rare diseases, and incorporates the optimal transport theory to identify the best transport scheme based on the semantic relationship among different diseases. Based on the best transport scheme, the GFC module calibrates the distribution of rare-disease features at the disease-shared channels, deriving more informative rare-disease features for better diagnosis. The proposed DCGG framework has been evaluated on three public medical image classification datasets. Our results suggest that the DCGG framework achieves state-of-the-art performance in diagnosing both common and rare diseases.

Multi-modality medical data provide complementary information, and hence have been widely explored for computer-aided AD diagnosis. However, the research is hindered by the unavoidable missing-data problem, i.e., one data modality was not acquired on some subjects due to various reasons. Although the missing data can be imputed using generative models, the imputation process may introduce unrealistic information to the classification process, leading to poor performance. In this paper, we propose the Disentangle First, Then Distill (DFTD) framework for AD diagnosis using incomplete multi-modality medical images. First, we design a region-aware disentanglement module to disentangle each image into inter-modality relevant representation and intra-modality specific representation with emphasis on disease-related regions. To progressively integrate multi-modality knowledge, we then construct an imputation-induced distillation module, in which a lateral inter-modality transition unit is created to impute representation of the missing modality. The proposed DFTD framework has been evaluated against six existing methods on an ADNI dataset with 1248 subjects. The results show that our method has superior performance in both AD-CN classification and MCI-to-AD prediction tasks, substantially over-performing all competing methods.