Evolutionary Neural Network and Visualization for CNN-based Pulmonary Textures Classification

Accurate classification and comprehensive explanation is crucial to build a computer aided diagnosis (CAD) system of diffuse lung disease (DLD). Although deep neural networks (DNNs) have been applied to this task, the classification performance and reliability are not satisfied for medical clinical requirements. Specifically, DNNs are regarded as unexplainable “black-box” in general, and, thus, are not deemed reliable by expects. In this paper, we propose a neural network structure search approach based on evolutionary algorithm to improve the DNN's effectiveness and interpretability, and applied to the pulmonary textures classification problem. Through this network structure search approach, we find out how a DNN's subnet recognize the pulmonary textures features, then filter out the redundant subnets, and retain the most distinctive feature subnets. Besides, we utilize the method of feature visualization and the fine-grained heat map of the activation to interpret network's decision-making process. Finally, through quantitatively and qualitatively evaluate on a real dataset of diffuse lung disease, we verify the effectiveness of this neural network structure search approach on VggNet and ResNet, and achieve the state-of-the-art performance. We can classify the pulmonary textures on high-resolution computed tomography (HRCT) images.