Alzheimer's disease diagnosis based on multiple cluster dense convolutional networks.

Alzheimer's disease (AD) is an irreversible neurodegenerative disorder with progressive impairment of memory and cognitive functions. Structural magnetic resonance images (MRI) play important role to evaluate the brain anatomical changes for AD Diagnosis. Machine learning technologies have been widely studied on MRI computation and analysis for quantitative evaluation and computer-aided-diagnosis of AD. Most existing methods extract the hand-craft features after image processing such as registration and segmentation, and then train a classifier to distinguish AD subjects from other groups. Motivated by the success of deep learning in image classification, this paper proposes a classification method based on multiple cluster dense convolutional neural networks (DenseNets) to learn the various local features of MR brain images, which are combined for AD classification. First, we partition the whole brain image into different local regions and extract a number of 3D patches from each region. Second, the patches from each region are grouped into different clusters with the K-Means clustering method. Third, we construct a DenseNet to learn the patch features for each cluster and the features learned from the discriminative clusters of each region are ensembled for classification. Finally, the classification results from different local regions are combined to enhance final image classification. The proposed method can gradually learn the MRI features from the local patches to global image level for the classification task. There are no rigid registration and segmentation required for preprocessing MRI images. Our method is evaluated using T1-weighted MRIs of 831 subjects including 199 AD patients, 403 mild cognitive impairment (MCI) and 229 normal control (NC) subjects from Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Experimental results show that the proposed method achieves an accuracy of 89.5% and an AUC (area under the ROC curve) of 92.4% for AD vs. NC classification, and an accuracy of 73.8% and an AUC of 77.5% for MCI vs. NC classification, demonstrating the promising classification performances.