IEEE Trans Med Imaging. 2022 Sep;41(9):2273-2284. doi: 10.1109/TMI.2022.3162111. Epub 2022 Aug 31.
Learning how to capture long-range dependencies and restore spatial information of down-sampled feature maps are the basis of the encoder-decoder structure networks in medical image segmentation. U-Net based methods use feature fusion to alleviate these two problems, but the global feature extraction ability and spatial information recovery ability of U-Net are still insufficient. In this paper, we propose a Global Feature Reconstruction (GFR) module to efficiently capture global context features and a Local Feature Reconstruction (LFR) module to dynamically up-sample features, respectively. For the GFR module, we first extract the global features with category representation from the feature map, then use the different level global features to reconstruct features at each location. The GFR module establishes a connection for each pair of feature elements in the entire space from a global perspective and transfers semantic information from the deep layers to the shallow layers. For the LFR module, we use low-level feature maps to guide the up-sampling process of high-level feature maps. Specifically, we use local neighborhoods to reconstruct features to achieve the transfer of spatial information. Based on the encoder-decoder architecture, we propose a Global and Local Feature Reconstruction Network (GLFRNet), in which the GFR modules are applied as skip connections and the LFR modules constitute the decoder path. The proposed GLFRNet is applied to four different medical image segmentation tasks and achieves state-of-the-art performance.
学习如何捕获长程依赖关系并恢复下采样特征图的空间信息是医学图像分割中编码器-解码器结构网络的基础。基于 U-Net 的方法使用特征融合来缓解这两个问题,但 U-Net 的全局特征提取能力和空间信息恢复能力仍然不足。在本文中,我们分别提出了全局特征重建(GFR)模块和局部特征重建(LFR)模块,以有效地捕获全局上下文特征和动态上采样特征。对于 GFR 模块,我们首先从特征图中提取具有类别表示的全局特征,然后使用不同层次的全局特征来重建每个位置的特征。GFR 模块从全局角度为整个空间中的每对特征元素建立连接,并将语义信息从深层传递到浅层。对于 LFR 模块,我们使用低层特征图来指导高层特征图的上采样过程。具体来说,我们使用局部邻域来重建特征,以实现空间信息的传递。基于编码器-解码器架构,我们提出了一种全局和局部特征重建网络(GLFRNet),其中 GFR 模块作为跳过连接应用,LFR 模块构成解码器路径。所提出的 GLFRNet 应用于四个不同的医学图像分割任务,并取得了最先进的性能。