Les Andrea S, Yeung Janice J, Schultz Geoffrey M, Herfkens Robert J, Dalman Ronald L, Taylor Charles A
Department of Bioengineering, Stanford University, Stanford, CA, USA.
Cardiovasc Eng Technol. 2010 Mar;1(1). doi: 10.1007/s13239-010-0004-8.
Hemodynamic forces are thought to play a critical role in abdominal aortic aneurysm (AAA) growth. and simulations can be used to study these forces, but require accurate aortic geometries and boundary conditions. Many AAA simulations use patient-specific geometries, but utilize inlet boundary conditions taken from a single, unrelated, healthy young adult.
In this study, we imaged 43 AAA patients using a 1.5 T MR scanner. A 24-frame cardiac-gated one-component phase-contrast magnetic resonance imaging sequence was used to measure volumetric flow at the supraceliac (SC) and infrarenal (IR) aorta, where flow information is typically needed for simulation. For the first 36 patients, individual waveforms were interpolated to a 12-mode Fourier curve, peak-aligned, and averaged. Allometric scaling equations were derived from log-log plots of mean SC and IR flow vs. body mass, height, body surface area (BSA), and fat-free body mass. The data from the last seven patients were used to validate our model.
Both the SC and IR averaged waveforms had the biphasic shapes characteristic of older adults, and mean SC and IR flows over the cardiac cycle were 51.2 ± 10.3 and 17.5 ± 5.44 mL/s, respectively. Linear regression of the log-log plots revealed that BSA was most strongly predictive of mean SC ( = 0.29) and IR flow ( = 0.19), with the highest combined . When averaged, the measured and predicted waveforms for the last seven patients agreed well.
We present a method to estimate SC and IR mean flows and waveforms for AAA simulation.
血流动力学力被认为在腹主动脉瘤（AAA）生长中起关键作用。模拟可用于研究这些力，但需要准确的主动脉几何形状和边界条件。许多AAA模拟使用患者特异性几何形状，但采用来自单一、不相关的健康年轻成年人的入口边界条件。
在本研究中，我们使用1.5 T MR扫描仪对43例AAA患者进行成像。使用24帧心脏门控单分量相位对比磁共振成像序列测量腹腔干上方（SC）和肾下腹主动脉（IR）的容积流量，这是模拟通常所需的流量信息。对于前36例患者，将个体波形内插为12模式傅里叶曲线，进行峰值对齐并求平均值。从平均SC和IR流量与体重、身高、体表面积（BSA）和去脂体重的对数-对数图中导出异速生长比例方程。最后7例患者的数据用于验证我们的模型。
SC和IR的平均波形均具有老年人特有的双相形状，心动周期内SC和IR的平均流量分别为51.2±10.3和17.5±5.44 mL/s。对数-对数图的线性回归显示，BSA对平均SC流量（r = 0.29）和IR流量（r = 0.19）的预测能力最强，综合r值最高。最后7例患者的测量波形和预测波形平均后吻合良好。
我们提出了一种估计用于AAA模拟的SC和IR平均流量及波形的方法。
