Modeling of ultrasound backscattering by aggregating red blood cells

International audienceThis chapter provides a review of the last 15 years on the use of quantitative ultrasound (QUS) techniques to characterize red blood cell (RBC) aggregation (i.e., aggregate size, structure and packing organization). The paper focuses on studies aimed at explaining factors affecting the frequency dependent backscatter coefficient (BSC). The theoretical structure factor model of ultrasound backscatter by aggregated RBCs is presented. Computer simulations based on this model are then described to understand the impact of the RBC aggregate size and packing organization on the frequency-dependent BSC. Two QUS cellular imaging methods, based respectively on the structure factor size estimator and the effective medium theory combined with the structure factor model, are compared to estimate the structural aggregate parameters. Finally, in vitro and in vivo results are presented with an optimization method to take into account the attenuation effects of intervening tissues between the probe and the blood flow