Assessment of accuracy of the structure-factor-size-estimator method in determining red blood cell aggregate size from ultrasound spectrum backscattering coefficient

Abstract

International audienceA computer simulation algorithm suitable for generating non-overlapping, isotropic and fairly identical red blood cell (RBC) clusters is presented. RBCs were stacked following the hexagonal close packing (HCP) structure to form a compact spherical aggregate. Such an aggregate was repeated and placed randomly under non-overlapping condition in three-dimensional space to mimic an aggregated blood sample. Backscattering coefficients (BSCs) were computed for samples at various cluster sizes and different hematocrits showing BSC increases with mean aggregate sizes. The accuracy of the structure factor size estimator (SFSE) method in determining mean aggregate size and packing factor were also examined. A good correlation (R2 ≥ 0.94) between the mean size of aggregates predicted by the SFSE and true size was found for each hematocrit. This study shows that for spherical aggregates there exists a region for each hematocrit where SFSE works most accurately. Typically, error of SFSE in estimating mean cluster size was < 20% for dimensions between 14-17 µm at 40% hematocrit. This study suggests that the theoretical framework of SFSE is valid under the assumption of isotropic aggregates