Aortic Hemodynamics in Patients With and Without Repair of Aortic Coarctation In Vivo Analysis by 4D Flow-Sensitive Magnetic Resonance Imaging
Aortic Hemodynamics in Patients With and Without Repair of Aortic Coarctation In Vivo Analysis by 4D Flow-Sensitive Magnetic Resonance Imaging
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DOI：
10.1097/rli.0b013e3182034fc2
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发表时间：
2011-05-01
影响因子：
6.7
通讯作者：
Arnold, Raoul
中科院分区：
文献类型：
--
作者：
Frydrychowicz, Alex;Markl, Michael;Arnold, Raoul
目的：本研究的目的是通过时间分辨、3 维和 3 向速度敏感相位对比磁共振成像 (4D PC MRI) 与健康受试者进行比较，描述接受或未接受手术修复的主动脉缩窄 (CoA) 患者的血流动力学变化和血流衍生血管壁参数。方法和材料：24 名患者，12.5 +/- CoA 修复后 6.4 年，对 4 名未接受 CoA 治疗的患者和 19 名健康受试者进行了检查。该研究得到了机构审查委员会的批准，并获得了参与者的书面知情同意书的签名。在参与之前对患者进行超声心动图检查。 MRI 研究是通过应用 1.5 T（n = 5 名患者）或 3 T（所有 19 名健康受试者，n = 23 名患者）的血流敏感 4D 相差 MRI 来进行的。血流可视化用于评估总体主动脉螺旋度、明显或额外的局部螺旋流的存在以及涡流发展。定量评估包括计算沿胸主动脉分布的 8 个位置以及 CoA 部位的区域时间平均绝对壁剪切应力 (WSS mag)、峰值速度和振荡剪切指数。确定了观察者之间和观察者内部计算的变异性。结果：志愿者和患者表现出相同量的总体主动脉螺旋度。相反，患者中额外的局部螺旋流或涡流形成的数量显着增加（25/28 患者 vs. 5/19 正常对照，Fisher 精确检验：P < 0.001）。 64.3% (18/28) 的患者检测到主动脉上分支孔口出现涡流，但对照组仅 11.8% (2/19) (P < 0.001)。定量分析显示，总体主动脉 WSS mag 显着增加（患者为 0.44 +/- 0.17 N/m(2)，志愿者为 0.27 +/- 0.08 N/m2，P < 0.005），总体振荡剪切指数有所下降。重复定量分析显示观察者间的变异性中等，观察者内的变异性较低。超声心动图的相关性与 MRI 具有良好的一致性，而 MRI 往往会低估峰值速度（r = 0.76；Bland-Altman 分析，一致性限 = -0.57-2.16 m/s，平均值 = 0.79 m/s）。结论：CoA 修复后主动脉血流动力学的改变并不限于修复的特定区域，而是可以在整个主动脉中发现。所提出的研究结果强调了该疾病的系统性本质以及对可由血流敏感 4D PC MRI 提供的系统性诊断方法的需求。此外，关于缩窄的血流动力学后果的有价值的额外见解已被证明可能有助于理解继发性并发症，例如再狭窄、动脉瘤形成和动脉高血压。
Objectives: The purpose of this study was to characterize hemodynamic alterations and flow-derived vessel wall parameters in aortic coarctation (CoA) patients with and without operative repair by time-resolved, 3-dimensional, and 3-directional velocity sensitive, phase-contrast magnetic resonance imaging (4D PC MRI) in comparison with healthy subjects.Methods and Material: Twenty-four patients, 12.5 +/- 6.4 years after CoA repair, 4 patients without treatment for CoA, and 19 healthy subjects were examined. The study was approved by the institutional review board and signature of written informed consent was obtained from the participants. Echocardiography was performed in patients before participation. MRI studies were conducted by applying flow-sensitive 4D phase-contrast MRI at either 1.5 T (n = 5 patients) or 3 T (all 19 healthy subjects, n = 23 patients). Blood flow visualization was used to evaluate overall aortic helicity, presence of pronounced or additional localized helix flow, and vortex development. Quantitative evaluation comprised the calculation of regional time-averaged absolute wall shear stress (WSS mag), peak velocities, and oscillatory shear index at 8 locations distributed along the thoracic aorta and additionally at the site of CoA. Inter-and intraobserver variabilities of calculations were determined.Results: Volunteers and patients demonstrated the same amount of overall aortic helicity. In contrast, the number of additional localized helix flow or vortex formation was significantly increased in patients (25/28 patients vs. 5/19 normal controls, Fisher exact test: P < 0.001). Vortices in the orifices of the supra-aortic branches were detected in 64.3% (18/28) of patients but in only 11.8% (2/19) of controls (P < 0.001). Quantitative analyses revealed a significant increase in overall aortic WSS mag (0.44 +/- 0.17 N/m(2) in patients vs. 0.27 +/- 0.08 N/m2 in volunteers, P < 0.005) and a decrease in overall oscillatory shear index. Repeated quantitative analysis showed moderate interobserver and low intraobserver variability. Correlation with echocardiography showed good agreement with MRI which tended to underestimate peak velocities (r = 0.76; Bland-Altman analysis, limits of agreement = -0.57-2.16 m/s, mean = 0.79 m/s).Conclusion: Alterations in aortic hemodynamics after CoA repair are not limited to the specific region of repair, but can be found in the entire aorta. The presented findings highlight the systemic nature of the disease and the need for a systemic diagnostic approach which can be provided by flow-sensitive 4D PC MRI. Furthermore, valuable additional insights on the hemodynamic consequences of coarctation have been shown that may help understanding secondary complications such as restenosis, aneurysm formation, and arterial hypertension.