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基于自注意力和自蒸馏的甲状腺结节恶性C-TIRADS危险分层检测方法

Method of Risk Stratification for Detecting Malignant C-TIRADS in Thyroid Nodules Based on Self-attention and Self-distillation

  • 摘要: 中国超声甲状腺影像报告与数据系统为判断甲状腺恶性结节的危险系数提供了指导标准. 为了解决现有方法检测精度低的问题, 提出一种符合C-TIRADS标准的基于自注意力和自蒸馏的甲状腺超声图像恶性危险分层检测方法. 首先通过融合卷积神经网络和自注意力模型ViT, 提高模型在甲状腺结节恶性危险分层检测中特征提取能力; 然后强化ViT和CNN的融合, 提出空间和通道瓶颈结构、空间和通道的交互模块, 实现跨维度、跨窗口和跨尺度的特征融合; 再引入改进的图卷积处理病理标签信息之间的相互联系, 对输出的特征向量进行矫正, 让模型学习病理标签之间的关联关系; 最后使用改进的噪声的学生自蒸馏的半监督学习的方式训练模型, 解决甲状腺结节数据集类别样本不平衡和小数据集容易过拟合的问题. 在真实数据集上进行消融和蒸馏实验, 并与7种不同方法进行对比实验, 结果表明, 所提方法是有效的, 在IoU阈值为0.50情况下, 该方法的mAP达到93.5%, 对于小型结节的mAP达到90.5%, 相比传统CNN有较大的提升.

     

    Abstract: The Chinese-thyroid imaging reporting and data system (C-TIRADS) provides a guideline for determining the risk factor of malignant thyroid nodules. In order to solve the problem of low detection accuracy of existing methods, a self-attention and self-distillation based malignant risk stratification detection method for thyroid ultrasound images in accordance with the C-TIRADS standard was proposed. First, by fusing the convolutional neural network (CNN) and the self-attention model ViT, the feature extraction ability of the model in the malignant risk stratification detection of thyroid nodules was improved; then the fusion of ViT and CNN was strengthened, and the spatial and channel bottleneck structure. Second, the interaction module of the spatial and channel was proposed, so as to achieve the feature fusion in the cross-dimension, cross-window, and cross-scalar scales. Third, the improved graph convolutions network was introduced to deal with the interconnections between the pathological labels, and the output feature vector was corrected to allow the model to learn the correlations between pathological labels. Finally, we proposed to train the model by semi-supervised learning using improved noisy student self-distillation, which solved the problems of the imbalance of samples among categories in the thyroid nodule dataset and the overfitting of small datasets. The ablation and distillation experiments were conducted on real datasets and compared with seven different methods. The results showed that the proposed method was effective, and the mAP of the method reached 93.5% with an IoU threshold of 0.5, and 90.5% for small nodules, which was a big improvement compared with the traditional CNN.

     

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