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基于自监督学习的医学影像异常检测

Self-Supervised Learning for Multi-Modal Medical Image Segmentation

  • 摘要: 自监督学习(SSL)可以很好地捕捉关于不同概念的通用知识, 有利于各种下游任务. 针对自监督学习方法没有充分利用医学图像的多模态特征等问题, 提出一种考虑医学图像多模态互补信息的自监督学习方法——SLeM. 该方法首先将单个模态的图像均匀地划分为4个块, 使用这些块随机组合构建多模态图像, 不同的多模态图像被分配不同的标签, 使得多模态特征可以通过分类任务来学习;为了提取不同大小肿瘤的特征, 在学习到的多模态特征后加入上下文融合块;通过简单的微调将学到的特征转移到下游的多模态医学图像分割任务中. 在公开数据集BraTS2019和CHAOS上与JiGen, Taleb以及Supervoxel等具有代表性的多模态方法对比及消融实验结果表明, 所提方法在整个肿瘤区域的分割准确度提升了2.03个百分点, 在肿瘤核心区域的分割准确度提升了3. 92个百分点, 在肿瘤增强区域的分割准确度提升了1.75个百分点, 并在视觉方面有较好的效果, 明显优于其他方法.

     

    Abstract: Self-supervised learning (SSL) can capture generic knowledge about different concepts, thereby beneficial for various downstream image analysis tasks. To address the shortcomings of underutilized multi-modal features in self-supervised learning methods for medical images, a self-supervised learning method considering multi-modal complementary information is proposed, named SLeM. This method first divides the four modalities into four blocks uniformly, these blocks are used to construct multi-modal images by randomly combining them, different multi-modal images are assigned different labels, and the multimodal feature representations can be learned by the classification task. The learned multi-modal features are followed by a contextual fusion block (CFB), which extracts features from tumors of various sizes. Finally, we transfer the learned representation to the downstream multi-modal medical image segmentation task via simple fine-tuning. Experiments conducted on public datasets BraTS and CHAOS were compared with multimodel baselines, including methods based on JiGen, Taleb and Supervoxel, etc. The results show that the segmentation accuracy of whole tumor, tumor core and enhanced tumor are improved by 2.03 percentage points, 3.92 percentage points and 1.75 percentage points, respectively. Meanwhile, the visual effect obtained by this method is also significantly better than others.

     

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