Ultrasonic Indirect Arterial Wall Shear Rate Measurement: Comparison Between A Centre- Line Velocity Method And Curve Fitting Of Velocity Profiles. Effects Of The Convolution

Numerous recent works have demonstrated the role of the arterial wall shear rate in the production of chemicals by endothelial cells Nevertheless in-vivo and noninvasive instantaneous wall shear rate measurement of this factor requires very precise velocity profiles knowledge . Such an accuracy is not generally possible to obtain , due to the finite volume sample measurement and the associated convolution effects . On the other hand the velocity data can be obtained with a good accuracy in the core of the vessel where the convolution effects are minimised . The indirect determination of the instantaneous wall shear rate in-vivo is then possible assuming the knowledge of the arterial centre-line velocity and using validated linear mathematical model .When non-linear terms are not negligible, the only approach is the curve fitting of velocity profiles. Nevertheless the convolution effects are predominant near the wall. A deconvolution process of the measured Doppler velocity profiles is then necessary for the evaluation of the wall shear rate in-vivo .