“…However, most of these traditional methods have problems such as complex design, poor versatility, and low segmentation accuracy. In recent years, deep learning has been widely used in medical image segmentation [ 11 , 12 , 13 , 14 , 15 , 16 ] and has achieved great success, especially the U-shaped and skip-connection based on convolution (UNet) [ 17 ], because it combines low-resolution information (providing the basis for object category recognition) and high-resolution information (providing the basis for precise segmentation and positioning), which is suitable for medical images segmentation. Then, researchers improved on the basis of UNet and proposed many better medical image segmentation methods [ 18 , 19 , 20 , 21 , 22 , 23 ] such as Att-UNet [ 18 ], Dense-UNet [ 19 ], R2U-Net [ 20 ], UNet++ [ 21 ], AG-Net [ 22 ], and UNet3+ [ 23 ].…”