4DFlow MRI对主动脉夹层患者腹部血流模式的定量研究及评估

Quantitative study on abdominal blood flow patterns in patients with aortic dissection using 4D flow MRI

目的:采用4D-flow MRI分析主动脉夹层(AD)患者腹部真腔和假腔内的血流动力学特点,以及各血流指标与夹层破口大小、数量及假腔内血栓之间的相关性,探讨其临床应用可行性及诊断价值。方法:16例主动脉夹层患者采用4DFlow MRI技术进行腹主动脉成像,同时行胸腹主动脉CTA检查。对腹主动脉4个层面的图像进行分析,测量各层面真腔和假腔的横断面积、血流速度、峰值速度、平均净流量、最大流量、净正向血容量及反流分数,并观察主动脉夹层各种形态学指标。真假腔各血流指标及面积的比较采用配对t检验,AD的各形态学指标与血流指标的关系采用Pearson相关分析和多元线性回归分析。结果:腹主动脉各水平真腔的平均横断面积及反流分数均小于假腔,真腔内血流速度、峰值速度、平均净流量、最大流量、净正向血容量均明显高于假腔,两组间差异均有统计学意义(P<0.05)。夹层破口越大,真腔血流速度及流量越小(P<0.05),而假腔的平均血流速度、平均净流量及最大流量越高(P<0.05)。随破口数量增多,真腔各血流指标增高(P<0.05),假腔最大流量变小(P=0.025)。假腔有血栓形成,则真腔平均血流速度、峰值速度增高(P=0.003、0.005)。破口大小对真假腔血流指标的影响意义较大。结论:4DFlow MRI技术能够定性、定量地提供主动脉夹层患者的腹主动脉血流信息,在主动脉夹层的诊断和治疗方案的选择中有重要的临床应用价值。

Objective：To evaluate the characteristics of abdominal hemodynamic changes in the true lumen （TL） and the false lumen （FL） in aortic dissections （AD） using 4D flow MRI,and to determine the relationship between blood flow indexes and the size, number of intimal entries and false lumen thrombosis, and to access the clinical feasibility and diagnos- tic value of 4D flow MRI. Methods： Sixteen AD patients underwent abdominal 4D flow MRI and thoracic and abdominal CTA at the same time. Images of abdominal aorta at four planes were quantitatively analyzed,the hemodynamic parameters including lumen area,velocity, peak velocity, average net flow volume, peak flow volume, net forward volume, and regurgi- tant fraction in the TL and FL were measured and compared using Paired t-test. The anatomic morphology of aortic dissection were also observed. The correlation between various morphological changes and hemodynamic parameters were analyzed using Pearson correlation analysis and multiple linear regression analysis. Results：The average area and regurgitant fraction of TL were significantly smaller than those of FL at all four levels （P〈0.05） ;the average velocity, peak velocity, average net flow volume,peak flow volume,net forward volume in TL were significantly higher than those in FL （P〈0.05）. With the increase of the size of intimal entry, the flow velocity and flow volume in TL were decreased （P〈0.05）, and the average velocity,average net flow volume, peak flow volume in FL were increased （P〈0. 05）. With the increase of intimal entry numbers,the hemodynamic parameters in the TL became higher （P〈 0. 05）, peak flow volume in the FL became lower （P-~ 0. 025） ;If there was thrombosis in false lumen, the average velocity and peak velocity in TL were higher （P= 0. 003, 0. 005）, the size of intimal entry had a strong impact on hemodynamic parameters in TL and FL. Conclusions：4D flow MRI provided qualitative and quantitative information on alterations of abdominal aortic blood flow in AD patients. It is important for clinical application in the diagnosis and therapeutic management choice of AD.