CR-U-Net: Cascaded U-Net with Residual Mapping for Liver Segmentation in CT Images

Abdominal computed tomography (CT) is a common modality to detect liver lesions. Liver segmentation in CT scan is important for diagnosis and analysis of liver lesions. However, the accuracy of existing liver segmentation methods is slightly insufficient. In this paper, we propose a liver segmentation architecture named CR-U-Net, which is composed of cascade U-Net combined with residual mapping. We make use of the MDice loss function for training in CR-U-Net, and the second-level of cascade network is deeper than the first-level to extract more detailed image features. Morphological algorithms are utilized as an intermediate-processing step to improve the segmentation accuracy. In addition, we evaluate our proposed CR-U-Net on liver segmentation task under the dataset provided by the 2017 ISBI LiTS Challenge. The experimental result demonstrates that our proposed CR-U-Net can outperform the state-of-the-art methods in term of the performance measures, such as Dice score, VOE, and so on.