RVS-FDSC: A retinal vessel segmentation method with four-directional strip convolution to enhance feature extraction

Abstract

Retinal vessel segmentation is important to assist ophthalmologists in the diagnosis and treatment of ophthalmic diseases. However, traditional convolutional neural networks (CNNs) are constrained by using square convolution kernels for retinal vessel feature extraction, thereby overlooking the structural characteristics of retinal vessels, which to some extent limits model performance. Consequently, we propose a retinal vessel segmentation method with four-directional strip convolution to enhance feature extraction (RVS-FDSC). Firstly, due to the shape structure of retinal vessels which have branching paths and appear locally as strips, we have constructed a residual strip convolution (RSC) module by using strip convolutions in four different directions: horizontal, vertical, antidiagonal, and main diagonal. These four directions can roughly simulate the branching directions of vessels, making it possible to better extract vessel features. Furthermore, to more comprehensively understand and utilize both local details and global context, RVS-FDSC introduces a multi-scale pooling feature fusion (MSPF2) module. Finally, to better focus on important features and reduce the attention to unimportant or redundant information, RVS-FDSC introduces a residual parallel dual attention (RPDA) module. We conduct experiments on three retinal vessel segmentation datasets: DRIVE, CHASE-DB1, and STARE. RVS-FDSC achieves excellent results on these three public datasets, with AUC of 0.9856, 0.9867, and 0.9808, Acc of 0.9692, 0.9743, and 0.9718, and Spe of 0.9878, 0.9856 and 0.9882, respectively. These results indicate the superior performance of RVS-FDSC compared to other state-of-the-art methods.