Estimation of aggregate size of red blood cell by introducing reference power spectrum measured for hemispherical ultrafine wire

Abstract

Noninvasive measurement of the degree of red blood cell (RBC) aggregation is useful for evaluating blood properties. In the present paper, we proposed a method to estimate the size of RBC aggregates without using the power spectrum of the posterior wall by introducing a reference scattering spectrum. The reference power spectra were calculated using the power spectrum measured for an ultrafine wire with a hemispherical tip. They were applied to the size estimation of microparticles simulating RBC aggregates. The estimated sizes were close to the true values, which shows that the calculated reference power spectra were suitable for accurate size estimation. The proposed method was also applied to in vivo measurements, and the estimated sizes between at rest and in RBCs aggregated by avascularization were successfully differentiated. This demonstrates that the proposed method will be useful for estimating the size of RBC aggregates.

In vivo measurement of attenuation coefficient of blood in a dorsal hand vein in a frequency range of 10–45 MHz: A preliminary study

“…However, it is difficult to prepare a reference phantom with a known attenuation coefficient in the frequency range in the present study. Therefore, the sound pressure property difference between different depths was corrected by measuring reflection spectra from the flat plate in water [24]. Ultrasonic waves transmitted from the ultrasound probe propagated through water in the membrane and skin and then irradiated the vascular lumen.…”

“…was determined in advance using the power spectra P R (f, d i ) and P R (f, d s ) of the waves reflected from the surface of a flat plate set at different depths d i and d s in water, respectively [24].…”

“…We have been studying methods for evaluating the size of red blood cell (RBC) aggregates by analyzing the scattering power spectrum obtained via ultrasonic backscattering measurements of RBCs [19][20][21][22][23][24]. Notably, the backscattering power obtained from a single sphere significantly depends on the frequency for each aggregate size [25], and the larger the diameter of a sphere, the smaller the slope of the frequency dependence of the power spectrum.…”

“…The size of RBC aggregates is estimated by fitting the slope of the measured power spectrum to that of a single scattering sphere's theoretically obtained scattering characteristics. To extract the scattering property from RBC aggregates, the power spectrum obtained from the vascular lumen is normalized by that obtained from the posterior wall of a blood vessel [20][21][22][23] or compared with the reference scattering spectrum [24]. To estimate the size of RBC aggregates with greater accuracy, the attenuation coefficients of the skin and blood must be measured, and the attenuation property differences between the two power spectra must be corrected [22][23][24].…”

“…To extract the scattering property from RBC aggregates, the power spectrum obtained from the vascular lumen is normalized by that obtained from the posterior wall of a blood vessel [20][21][22][23] or compared with the reference scattering spectrum [24]. To estimate the size of RBC aggregates with greater accuracy, the attenuation coefficients of the skin and blood must be measured, and the attenuation property differences between the two power spectra must be corrected [22][23][24]. To measure the attenuation coefficient, power spectra at only two different depths were used.…”