Characterization of visco-elastic vessel wall mechanical properties from ultrasound Doppler measurements

The constant monitoring of mechanical vessel properties could help the physicians to classify patient illness, but performing the non invasive measurement of such parameters is quite difficult. This work presents an approach to quantify the mechanical properties of vessels wall tissues from the simultaneous measurement of vessel hydrostatic pressure and wall deformations. A "Zener" visco-elastic mechanical model is introduced to reproduce the wall tissue kinematics and in particular the de-phasing between arterial wall pressure and deformation. The mechanical model is shown equivalent to its electrical analogue, and is described as a linear system in the frequency domain. An ARMA approach has been used to solve the inverse problem and retrieve the mechanical parameters of the model transfer function. Stress and strain reference signals are obtained by finite element simulation. Compared to a simulated reference, a low relative error is observed in the estimation of the model parameters