Models based on U-like structures have improved the performance of medical image segmentation. However, the single-layer decoder structure of U-Net is too "thin" to exploit enough information, resulting in large semantic differences between the encoder and decoder parts. Things get worse if the number of training sets of data is not sufficiently large, which is common in medical image processing tasks where annotated data are more difficult to obtain than other tasks. Based on this observation, we propose a novel U-Net model named MS-UNet for the medical image segmentation task in this study. Instead of the single-layer U-Net decoder structure used in Swin-UNet and TransUnet, we specifically design a multi-scale nested decoder based on the Swin Transformer for U-Net. The proposed multi-scale nested decoder structure allows the feature mapping between the decoder and encoder to be semantically closer, thus enabling the network to learn more detailed features. In addition, we propose a novel edge loss and a plug-and-play fine-tuning Denoising module, which not only effectively improves the segmentation performance of MS-UNet, but could also be applied to other models individually. Experimental results show that MS-UNet could effectively improve the network performance with more efficient feature learning capability and exhibit more advanced performance, especially in the extreme case with a small amount of training data, and the proposed Edge loss and Denoising module could significantly enhance the segmentation performance of MS-UNet.

基于医学图像分割任务，我们提出了一种名为MS-UNet的新型U-Net模型。与Swin-UNet和TransUnet中使用的单层U-Net解码器结构不同，我们专门为U-Net设计了基于Swin Transformer的多尺度嵌套解码器。我们还提出了一种新颖的边界损失和即插即用微调去噪模块，这不仅有效提高了MS-UNet的分割性能，还可以单独应用于其他模型。实验证明，MS-UNet在更高效的特征学习能力方面有效提升了网络性能，尤其是在少量训练数据的极端情况下，并且所提出的边界损失和去噪模块能显著增强MS-UNet的分割性能。

MS-UNet-v2: 医学图像分割的自适应降噪方法与小数据训练策略