| 1 | 基于U-Net神经网络的多模态MR颈动脉血管成像的分割方法研究显示文摘目的 探讨基于U-Net神经网络的多模态MR影像颈动脉血管分割方法的价值.方法 回顾性分析了2012年至2015年中国动脉粥样硬化风险评估研究项目中,经标准多模态MR扫描,且两周内出现缺血性脑卒中或短暂性脑缺血的患者.经纳入标准和排除标准筛选后,有658例患者共17 568层颈动脉血管壁影像纳入研究.应用定制设计的心血管疾病评估计算机辅助系统(CASCADE,华盛顿大学血管成像实验室,西雅图)对所有影像数据进行分析.按照训练集、验证集和测试集6∶2∶2的比例,随机选取10 592个样本作为训练集,3 488个样本作为验证集,3 488个样本作为测试集.为防止模型过拟合,提高模型泛化能力,对原始的多模态血管斑块MR影像进行数据增强.应用经过微调的U-Net神经网络构建多模态MR影像颈动脉血管分割模型,在训练集上训练,在验证集上验证并优化训练超参数,在测试集上测试并计算像素级别的颈动脉血管分割的敏感度、特异度和Dice系数,并计算U-Net分割方法和手工分割方法下的最大管壁厚度和管壁面积,利用组内相关系数和Bland-Altman分析来验证两种方法的一致性.结果 在测试集上应用训练得到的U-Net神经网络模型进行颈动脉血管分割,计算敏感度为0.878,特异度为0.986,Dice系数为0.858.最大管壁厚度的组内相关系数(95%可信区间)为0.921(0.915~0.925),管壁面积的组内相关系数(95%可信区间)为0.929 (0.924~0.933),Bland-Altman分析中最大管壁厚度差值为(0.037±0.316)mm,管壁面积差值为(1.182± 4.953)mm2,U-Net分割方法和手工分割方法具有较高一致性.结论 应用U-Net神经网络的方法,在大规模经过专业医师标注的数据集上进行训练和验证,可以实现对多模态MR影像颈动脉血管自动分割. | 李继凡 陈硕 章强 宋焱 Gador Canton 孙杰 许东翔 赵锡海 苑纯 李睿 | 2019 | 中华放射学杂志2019，53，12： | 7 |
| 5 | Using Multiple Risk Factors and Generalized Linear Mixed Models with 5-Fold Cross-Validation Strategy for Optimal Carotid Plaque Progression Prediction显示文摘Background Cardiovascular diseases are closely linked to atherosclerotic plaque development and rupture.Plaque progression prediction is of fundamental significance to cardiovascular research and disease diagnosis,prevention,and treatment.Generalized linear mixed models(GLMM)is an extension of linear model for categorical responses while considering the correlation among observations.Methods Magnetic resonance image(MRI)data of carotid atheroscleroticplaques were acquired from 20 patients with consent obtained and 3D thin-layer models were constructed to calculate plaque stress and strain for plaque progression prediction.Data for ten morphological and biomechanical risk factors included wall thickness(WT),lipid percent(LP),minimum cap thickness(MinCT),plaque area(PA),plaque burden(PB),lumen area(LA),maximum plaque wall stress(MPWS),maximum plaque wall strain(MPWSn),average plaque wall stress(APWS),and average plaque wall strain(APWSn)were extracted from all slices for analysis.Wall thickness increase(WTI),plaque burden increase(PBI)and plaque area increase(PAI) were chosen as three measures for plaque progression.Generalized linear mixed models(GLMM)with 5-fold cross-validation strategy were used to calculate prediction accuracy for each predictor and identify optimal predictor with the highest prediction accuracy defined as sum of sensitivity and specificity.All 201 MRI slices were randomly divided into 4 training subgroups and 1 verification subgroup.The training subgroups were used for model fitting,and the verification subgroup was used to estimate the model.All combinations(total1023)of 10 risk factors were feed to GLMM and the prediction accuracy of each predictor were selected from the point on the ROC(receiver operating characteristic)curve with the highest sum of specificity and sensitivity.Results LA was the best single predictor for PBI with the highest prediction accuracy(1.360 1),and the area under of the ROC curve(AUC)is0.654 0,followed by APWSn(1.336 3)with AUC=0.6342.The optimal predictor among all possible combinations for PBI was the combination of LA,PA,LP,WT,MPWS and MPWSn with prediction accuracy=1.414 6(AUC=0.715 8).LA was once again the best single predictor for PAI with the highest prediction accuracy(1.184 6)with AUC=0.606 4,followed by MPWSn(1. 183 2)with AUC=0.6084.The combination of PA,PB,WT,MPWS,MPWSn and APWSn gave the best prediction accuracy(1.302 5)for PAI,and the AUC value is 0.6657.PA was the best single predictor for WTI with highest prediction accuracy(1.288 7)with AUC=0.641 5,followed by WT(1.254 0),with AUC=0.6097.The combination of PA,PB,WT,LP,MinCT,MPWS and MPWS was the best predictor for WTI with prediction accuracy as 1.314 0,with AUC=0.6552.This indicated that PBI was a more predictable measure than WTI and PAI. The combinational predictors improved prediction accuracy by 9.95%,4.01%and 1.96%over the best single predictors for PAI,PBI and WTI(AUC values improved by9.78%,9.45%,and 2.14%),respectively.Conclusions The use of GLMM with 5-fold cross-validation strategy combining both morphological and biomechanical risk factors could potentially improve the accuracy of carotid plaque progression prediction.This study suggests that a linear combination of multiple predictors can provide potential improvement to existing plaque assessment schemes. | Qingyu Wang Dalin Tang Liang Wang Gador Canton Zheyang Wu Thomas SHatsukami Kristen L Billiar Chun Yuan | 2019 | 医用生物力学2019，34，A01： | 0 |
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