Quantification of Doppler color flow images from a stenosed carotid artery model.

Velocity fields at and downstream of graded, axisymmetric stenoses of 0%, 20%, 40%, 60% and 80% diameter reduction were obtained under pulsatile flow conditions simulating that in a carotid artery (Re(mean) = 379, Re(peak) = 1137 and alpha = 5.36) using an ultrasonic Doppler Color Flow Imager. Characteristic features of flow disturbances associated with degree of stenosis, such as jetting, flow separation and reversal and turbulence were quantified using nondimensional indices at peak systole, t0, and early diastole, t1. It was found that the Reverse Area Index (RAI), the Field Profile Index (FPI) and the Velocity Gradient Indices (VGIz and VGIr) were sensitive to these changes, especially at time t1. In particular, the mean values of RAI and VGIr were significantly different for all stenotic cases. These findings may provide a more quantitative and reproducible method of interpreting flow patterns in the region of stenosed carotid arteries.