Early Alzheimer's risk detection via diffusion tensor imaging using a few-shot multichannel attention residual learning network.

Introduction: Alzheimer's disease (AD) is responsible for many dementia-related deaths worldwide, and Mild Cognitive Impairment (MCI) is often its earliest clinical manifestation. Early detection of MCI is essential to initiate timely interventions that can slow progression and improve the patient's quality of life. The emergence of diffusion tensor imaging (DTI) has made it a powerful neuroimaging modality for MCI detection, offering greater sensitivity to microstructural changes in white matter than basic structural imaging. Methods: A Multichannel Attention Residual Learning-DTI (MARL-DTI) architecture was designed with attention mechanisms and residual learning utilizing multiple DTI-derived diffusion metrics, including fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AxD). To overcome the scarcity of labelled neuroimaging data, the model was supplemented with a few-shot learning framework. The dataset comprised 239 DTI scans from ADNI was used to evaluate the model. Local Interpretable Model-Agnostic Explanations (LIME) assists in analysing the model's decision-making process behaviour. Results: The proposed MARL-DTI achieved a classification accuracy of 92.76%, outperforming baseline DenseNet variants, StatFusion-FCNN, and Matching Networks. Validation on an unseen dataset of 36 ADNI subjects yielded consistent accuracy (91.67%), confirming the model's reliability. LIME analysis was used to provide instance-level explanations, enabling qualitative assessment of the model's decision-making behaviour by highlighting feature contributions for individual predictions. Discussion: These results demonstrate that the proposed MARL-DTI framework surpasses traditional deep learning architectures in the early identification of MCI using DTI data. The model consistently achieved strong performance while maintaining transparency, using LIME as a validation tool to examine its decision-making behaviour. These findings highlight the potential of combining multi-channel volumetric DTI data with explainable deep learning approaches to support reliable and clinically relevant early detection of Alzheimer's disease.