Modeling and simulation of the ultrasound signal backscattered by blood

A new model is proposed to simulate the power backscattered by blood. The model is that of a space-invariant linear system which takes into consideration the blood stochastic scattering properties as well as the characteristics of the ultrasound system. The model allowed the study of the backscattered power as a function of the hematocrit for nonaggregating red blood cells (RBCs), and the level of RBC aggregation determined by the flow shear rate. RBC aggregation was simulated in a Couette flow at 40% hematocrit and shear rates of 0.01 s/sup -1/ to 10 s/sup -1/. For nonaggregating RBCs, the power as a function of the hematocrit matched theoretical predictions and experimental results. The maximum aggregation and backscattered power were obtained around 0.6 s/sup -1/.