The pathophysiology of major depressive disorder (MDD) has been explored to be highly associated with the dysfunctional integration of brain networks. It is therefore imperative to explore neuroimaging biomarkers to aid diagnosis and treatment. In this study, we developed a spatiotemporal graph convolutional network (STGCN) framework to learn discriminative features from functional connectivity for automatic diagnosis and treatment response prediction of MDD. Briefly, dynamic functional networks were first obtained from the resting‐state fMRI with the sliding temporal window method. Secondly, a novel STGCN approach was proposed by introducing the modules of spatial graph attention convolution (SGAC) and temporal fusion. A novel SGAC was proposed to improve the feature learning ability and special anatomy prior guided pooling was developed to enable the feature dimension reduction. A temporal fusion module was proposed to capture the dynamic features of functional connectivity between adjacent sliding windows. Finally, the STGCN proposed approach was utilized to the tasks of diagnosis and antidepressant treatment response prediction for MDD. Performances of the framework were comprehensively examined with large cohorts of clinical data, which demonstrated its effectiveness in classifying MDD patients and predicting the treatment response. The sound performance suggests the potential of the STGCN for the clinical use in diagnosis and treatment prediction.

Deformable medical image registration estimates corresponding deformation to align the regions of interest (ROIs) of two images to a same spatial coordinate system. However, recent unsupervised registration models only have correspondence ability without perception, making misalignment on blurred anatomies and distortion on task-unconcerned backgrounds. Label-constrained (LC) registration models embed the perception ability via labels, but the lack of texture constraints in labels and the expensive labeling costs causes distortion internal ROIs and overfitted perception. We propose the first few-shot deformable medical image registration framework, Perception-Correspondence Registration (PC-Reg) , which embeds perception ability to registration models only with few labels, thus greatly improving registration accuracy and reducing distortion. 1) We propose the Perception-Correspondence Decoupling which decouples the perception and correspondence actions of registration to two CNNs. Therefore, independent optimizations and feature representations are available avoiding interference of the correspondence due to the lack of texture constraints. 2) For few-shot learning, we propose Reverse Teaching which aligns labeled and unlabeled images to each other to provide supervision information to the structure and style knowledge in unlabeled images, thus generating additional training data. Therefore, these data will reversely teach our perception CNN more style and structure knowledge, improving its generalization ability. Our experiments on three datasets with only five labels demonstrate that our PC-Reg has competitive registration accuracy and effective distortion-reducing ability. Compared with LC-VoxelMorph( $\lambda =1$ ), we achieve the 12.5%, 6.3% and 1.0% Reg-DSC improvements on three datasets, revealing our framework with great potential in clinical application.

Major depressive disorder (MDD) is a common and severe psychiatric illness marked by loss of interest and low energy, which result in the highest burden of disability among all mental disorders. Clinical MDD diagnosis still utilizes the phenomenological approach of syndrome-based interview, which leads to a high rate of misdiagnosis. Therefore, it is highly imperative to explore effective biomarkers to enable precise personalized diagnosis. There still exist two main challenges due to complexity of MDD and individual differences. On the one hand, discriminative features need to be investigated to better reflect the characteristics of MDD. On the other hand, the performance from shallow and static learning models is still not satisfactory. To overcome these issues, we propose a novel Multi-Stage Graph Fusion Networks (MSGFN) for major depressive disorder diagnosis. At first, functional connectivity is calculated to better characterize interactions between white matter and gray matter. Secondly, multi-stage features are obtained by a deep subspace learning model, and a number of graphs are constructed under the self-expression constraints at each stage. Finally, a novel graph convolutional fusion module is proposed with graph convolutional operations to integrate features and graph at each stage. Extensive experiments demonstrate the superior performance of the proposed framework. Our source code is available on: https://github.com/LIST-KONG/MSGFN-master.