IA-net: informative attention convolutional neural network for choroidal neovascularization segmentation in OCT images.

Choroidal neovascularization (CNV) is a characteristic feature of wet age-related macular degeneration (AMD). Quantification of CNV is useful to clinicians in the diagnosis and treatment of CNV disease. Before quantification, CNV lesion should be delineated by automatic CNV segmentation technology. Recently, deep learning methods have achieved significant success for medical image segmentation. However, some CNVs are small objects which are hard to discriminate, resulting in performance degradation. In addition, it's difficult to train an effective network for accurate segmentation due to the complicated characteristics of CNV in OCT images. In order to tackle these two challenges, this paper proposed a novel Informative Attention Convolutional Neural Network (IA-net) for automatic CNV segmentation in OCT images. Considering that the attention mechanism has the ability to enhance the discriminative power of the interesting regions in the feature maps, the attention enhancement block is developed by introducing the additional attention constraint. It has the ability to force the model to pay high attention on CNV in the learned feature maps, improving the discriminative ability of the learned CNV features, which is useful to improve the segmentation performance on small CNV. For accurate pixel classification, the novel informative loss is proposed with the incorporation of an informative attention map. It can focus training on a set of informative samples that are difficult to be predicted. Therefore, the trained model has the ability to learn enough information to classify these informative samples, further improving the performance. The experimental results on our database demonstrate that the proposed method outperforms traditional CNV segmentation methods.