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

Abstract

A computer simulation study to produce ultrasonic backscatter coefficients (BSCs) from red blood cell (RBC) clusters is discussed. The simulation algorithm is suitable for generating non-overlapping, isotropic, and fairly identical RBC clusters. 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 the three-dimensional space to mimic an aggregated blood sample. BSCs were computed between 750 KHz and 200 MHz for samples of various cluster sizes at different hematocrits. Magnitudes of BSCs increased with mean aggregate sizes at low frequencies (<20 MHz). The accuracy of the structure-factor-size-estimator (SFSE) method in determining mean aggregate size and packing factor was also examined. A good correlation (R 2 ! 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 and 17 lm at 40% hematocrit. This study suggests that the theoretical framework of SFSE is valid under the assumption of isotropic aggregates.

Coherent and incoherent ultrasound backscatter from cell aggregates

“…The SFM is an ultrasound scattering model largely used to predict the frequency dependence of the BSC from aggregated cells in the field of ultrasound tissue characterization. 4,8,10,14,17 The SFM consists of summing contributions from individual cells and modeling cell interaction by a statistical mechanics structure factor, whatever the complexity of the cells spatial distribution such as cell aggregates. The structure factor computation for a complex particle spatial distribution was described in details in Section 6.3.1 of Ref.…”

“…where r j is the position vector of the jth cell with respect to the aggregate center, as given in Eq. (6) of Saha et al 14 So, the radius r of the equivalent full sphere must be expressed as: r = 5 3 R g , as demonstrated in Appendix B. Henceforth, from Eq.…”

A simulation study on photoacoustic signals from red blood cells

“…This approach has been successfully used in modeling ultrasound backscatter. 16 The mean radius of gyration of clusters for each aggregation level was computed to indicate effective cluster size. The PA signal properties such as signal envelope statistics and frequency dependent power spectra were investigated for these two types of blood samples.…”

Pilot clinical study of quantitative ultrasound spectroscopy measurements of erythrocyte aggregation within superficial veins

“…Both D and W parameters increase with the enhancement of RBC aggregation. Based on simulations [18], it was demonstrated that W = C 1 × D 2 + C 2 , where constants C 1 and C 2 are close to 1.0 and 0.0, respectively. Values of these constants are influenced by the hematocrit that is an input parameter of the SFSAE model.…”