Glo-net: A dual task branch based neural network for multi-class glomeruli segmentation

Accurate segmentation and classification of glomeruli are fundamental to histopathology slide analysis in renal pathology, which helps to characterize individual kidney disease. Accurate segmentation of glomeruli of different types faces two main challenges compared to traditional primitives segmentation in computational image analysis. Limited by small kernel size, traditional convolutional neural networks could hardly understand the complete context information of different glomeruli. Moreover, typical semantic segmentation networks lack adequate attention to difficult glomerular samples during the training process due to serious class imbalance between different glomeruli types. We propose a new deep learning approach, Glo-Net, which accurately segments and classifies glomeruli based on digitized pathology slides. Specifically, Glo-Net divides the traditional semantic segmentation network into two branches, i.e., segmentation and classification. While the segmentation branch specifically aims at localizing and delineating the boundary of individual glomerulus, the classification branch could focus on differentiating the glomerular types based on segmented pixels. In addition, an innovative loss function is added to the classification task to compensate for the class imbalance and minor types of glomeruli. The proposed network's average accuracy and F-score in classification tasks on the multi-institution datasets (including an external validation set) are 0.858 and 0.704, respectively. The average intersection over union (IoU) in segmentation tasks is 0.866. The Glo-Net demonstrates a 5 % improvement in classification accuracy, with up to 14 % increases for minor classes and an average 6 % IoU increase for segmentation tasks. Quantitative results show that our network achieves overall higher accuracy for segmentation and classification among nine subtypes of glomeruli compared to previous work with improved robustness and generalizability.