论文标题
R2U ++:一种多尺度的剩余U-NET,具有密集的跳过连接用于医疗图像分段
R2U++: A Multiscale Recurrent Residual U-Net with Dense Skip Connections for Medical Image Segmentation
论文作者
论文摘要
U-NET是医学图像分割领域中广泛采用的神经网络。尽管医学成像社区很快就接受了它,但其性能在复杂的数据集上受到了影响。问题可以归因于其简单的功能提取块:编码器/解码器以及编码器和解码器之间的语义差距。已经提出了U-NET(例如R2U-NET)的变体,以通过使网络更深地解决简单功能提取块的问题,但并不涉及语义差距问题。另一方面,另一个变体UNET ++通过引入密集的跳过连接来处理语义差距问题,但具有简单的特征提取块。为了克服这些问题,我们提出了一种新的基于U-NET的医疗图像分割体系结构R2U ++。在拟议的架构中,Vanilla U-NET的适应性变化是:(1)普通的卷积骨架被更深的复发式卷积块所取代。这些块的视野增加了,有助于提取分割的关键特征,这可以通过改善网络的整体性能来证明。 (2)编码器和解码器之间的语义差距通过密集的跳过途径减少。这些途径积累了来自多个尺度的特征,并相应地应用串联。修改后的体系结构已嵌入了多深度模型,从不同深度获得的一组输出可以改善图像中各个尺度上出现的前景对象的性能。 R2U ++的性能在四种不同的医学成像方式上进行了评估:电子显微镜(EM),X射线,眼底和计算机断层扫描(CT)。 IOU分数的平均增益为1.5+-0.37%,骰子得分比UNET ++的平均增长率为0.9+-0.33%,而IOU中的4.21+-2.72在不同的医学成像分段数据集中,R2U-NET上的骰子分数为4.21+-2.72。
U-Net is a widely adopted neural network in the domain of medical image segmentation. Despite its quick embracement by the medical imaging community, its performance suffers on complicated datasets. The problem can be ascribed to its simple feature extracting blocks: encoder/decoder, and the semantic gap between encoder and decoder. Variants of U-Net (such as R2U-Net) have been proposed to address the problem of simple feature extracting blocks by making the network deeper, but it does not deal with the semantic gap problem. On the other hand, another variant UNET++ deals with the semantic gap problem by introducing dense skip connections but has simple feature extraction blocks. To overcome these issues, we propose a new U-Net based medical image segmentation architecture R2U++. In the proposed architecture, the adapted changes from vanilla U-Net are: (1) the plain convolutional backbone is replaced by a deeper recurrent residual convolution block. The increased field of view with these blocks aids in extracting crucial features for segmentation which is proven by improvement in the overall performance of the network. (2) The semantic gap between encoder and decoder is reduced by dense skip pathways. These pathways accumulate features coming from multiple scales and apply concatenation accordingly. The modified architecture has embedded multi-depth models, and an ensemble of outputs taken from varying depths improves the performance on foreground objects appearing at various scales in the images. The performance of R2U++ is evaluated on four distinct medical imaging modalities: electron microscopy (EM), X-rays, fundus, and computed tomography (CT). The average gain achieved in IoU score is 1.5+-0.37% and in dice score is 0.9+-0.33% over UNET++, whereas, 4.21+-2.72 in IoU and 3.47+-1.89 in dice score over R2U-Net across different medical imaging segmentation datasets.