Computer Vision Center, 08193 Bellaterra, Spain.
Phys Med Biol. 2010 Jun 21;55(12):3557-75. doi: 10.1088/0031-9155/55/12/019. Epub 2010 May 28.
Human arteries affected by atherosclerosis are characterized by altered wall viscoelastic properties. The possibility of noninvasively assessing arterial viscoelasticity in vivo would significantly contribute to the early diagnosis and prevention of this disease. This paper presents a noniterative technique to estimate the viscoelastic parameters of a vascular wall Zener model. The approach requires the simultaneous measurement of flow variations and wall displacements, which can be provided by suitable ultrasound Doppler instruments. Viscoelastic parameters are estimated by fitting the theoretical constitutive equations to the experimental measurements using an ARMA parameter approach. The accuracy and sensitivity of the proposed method are tested using reference data generated by numerical simulations of arterial pulsation in which the physiological conditions and the viscoelastic parameters of the model can be suitably varied. The estimated values quantitatively agree with the reference values, showing that the only parameter affected by changing the physiological conditions is viscosity, whose relative error was about 27% even when a poor signal-to-noise ratio is simulated. Finally, the feasibility of the method is illustrated through three measurements made at different flow regimes on a cylindrical vessel phantom, yielding a parameter mean estimation error of 25%.
受动脉粥样硬化影响的人体动脉的特征在于其壁粘弹性特性发生了改变。能够在体内非侵入性地评估动脉粘弹性，将极大地有助于这种疾病的早期诊断和预防。本文提出了一种非迭代技术来估计血管壁 Zener 模型的粘弹性参数。该方法需要同时测量流量变化和壁位移，这可以通过适当的超声多普勒仪器来提供。通过使用 ARMA 参数方法将理论本构方程拟合到实验测量值，来估计粘弹性参数。使用通过对动脉搏动的数值模拟生成的参考数据来测试所提出方法的准确性和灵敏度，其中可以适当改变模型的生理条件和粘弹性参数。估计值与参考值定量一致，表明仅受生理条件变化影响的参数是粘度，即使在模拟较差的信噪比的情况下，其相对误差也约为 27%。最后，通过在圆柱形容器模型上在不同流态下进行的三次测量，说明了该方法的可行性，得出了参数均值估计误差为 25%。
