Vascular Mechanics Laboratory, Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, USA.
Eur J Vasc Endovasc Surg. 2013 Oct;46(4):447-52. doi: 10.1016/j.ejvs.2013.07.011. Epub 2013 Aug 7.
This study was performed to determine the feasibility of measuring the elastic properties of the arterial wall in vivo. To prove this concept, elastic parameters were calculated from an aortic model of elastic behavior similar to a human aorta using computed tomography angiography (CTA) images.
We first constructed an aortic model from polydimethylsiloxane (PDMS). This model was inserted into a pulsatile flow loop. The model was then placed inside a computed tomography scanner. To estimate the elasticity values, we measured the cross-sectional area and the pressure changes in the model during each phase of the simulated cardiac cycle. A discrete wavelet transform (DWT) algorithm was applied to the CTA data to calculate the geometric changes in the pulsatile model over a simulated cardiac cycle for various pulsatile rates and elasticity values of the PDMS material. The elastic modulus of the aortic model wall was derived from these geometric changes. The elastic moduli derived from the CTA data were compared with those obtained by testing strips of the same PDMS material in a tensile testing machine. Our two aortic models had elastic values at both extremes of those found in normal human aortas.
The results show a good comparison between the elastic values derived from the CTA data and those obtained in a tensile testing machine. In addition, the elasticity values were found to be independent of the pulsatile rate for mixing ratios of 6:1 and 9:1 (p = .12 and p = .22, respectively).
The elastic modulus of a pulsatile aortic model may be measured by electrocardiographically-gated multi-detector CTA protocol. This preliminary study suggests the possibility of determining non-invasively the elastic properties of a living, functioning aorta using CTA data.
本研究旨在确定活体测量动脉壁弹性特性的可行性。为了证明这一概念，使用计算机断层血管造影（CTA）图像计算了类似于人体主动脉的弹性行为的主动脉模型的弹性参数。
我们首先用聚二甲基硅氧烷（PDMS）构建了一个主动脉模型。该模型被插入脉动流回路中。然后将模型放置在计算机断层扫描仪内。为了估计弹性值，我们在模拟心动周期的每个阶段测量模型的截面积和压力变化。离散小波变换（DWT）算法应用于 CTA 数据，以计算脉动模型在模拟心动周期内的几何变化，用于各种脉动率和 PDMS 材料的弹性值。从这些几何变化中得出主动脉模型壁的弹性模量。从 CTA 数据得出的弹性模量与在拉伸试验机中测试相同 PDMS 材料条带获得的弹性模量进行了比较。我们的两个主动脉模型具有正常人体主动脉发现的弹性值的两个极端值。
结果表明，从 CTA 数据得出的弹性值与在拉伸试验机中获得的弹性值之间存在良好的比较。此外，对于混合比为 6:1 和 9:1 的情况，发现弹性值与脉动率无关（p =.12 和 p =.22，分别）。
通过心电图门控多探测器 CTA 协议可以测量脉动主动脉模型的弹性模量。这项初步研究表明，使用 CTA 数据无创地确定活体、功能主动脉的弹性特性是可能的。
