Optimal transport based pyramid graph kernel for autism spectrum disorder diagnosis

Abstract

Brain network, which characterizes the functional and structural interactions of brain regions with graph theory, has been widely utilized to diagnose brain diseases, such as autism spectrum disorder (ASD). It is a challenge to measure the network (or graph) similarity in brain network analysis. Graph kernel (i.e., kernel defined on graphs) offers an efficient tool for measuring the similarity of paired brain networks and yields the excellent classification performance in brain disease diagnosis. However, most of the existing graph kernels neglected the hierarchical architecture information of brain networks. To address this problem, in this paper, we propose an optimal transport based pyramid graph kernel for measuring brain network similarity and then apply it to brain disease classification. The main idea is to transform brain networks into pyramid structures, which reflect the hierarchical architecture information of the brain network with multi-resolution histograms. The optimal transport distance in pyramid structures is calculated for measuring transport costs between paired brain networks. Finally, the optimal transport based pyramid graph kernel is computed based on this optimal transport distance. To evaluate the effectiveness of the proposed optimal transport based pyramid graph kernel, the extensive experiments are performed in functional magnetic resonance imaging data of brain disease from the Autism Brain Imaging Data Exchange database. The experimental results show that our proposed optimal transport based pyramid graph kernel outperforms the state-of-the-art methods in ASD classification tasks.