Simultaneous assessment of red blood cell aggregation and oxygen saturation under pulsatile flow using high-frequency photoacoustics

Abstract

We investigate the feasibility of photoacoustic (PA) imaging for assessing the correlation between red blood cell (RBC) aggregation and the oxygen saturation (sO2) in a simulated pulsatile blood flow system. For the 750 and 850 nm illuminations, the PA amplitude (PAA) increased and decreased as the mean blood flow velocity decreased and increased, respectively, at all beat rates (60, 120 and 180 bpm). The sO2 also cyclically varied, in phase with the PAA for all beat rates. However, the linear correlation between the sO2 and the PAA at 850 nm was stronger than that at 750 nm. These results suggest that the sO2 can be correlated with RBC aggregation induced by decreased mean shear rate in pulsatile flow, and that the correlation is dependent on the optical wavelength. The hemodynamic properties of blood flow assessed by PA imaging may be used to provide a new biomarker for simultaneous monitoring blood viscosity related to RBC aggregation, oxygen delivery related to the sO2 and their clinical correlation.

A Handheld Real-Time Photoacoustic Imaging System for Animal Neurological Disease Models: From Simulation to Realization

“…A cranial window was created for both ischemic stroke induction and PA imaging [ 2 ]. The PTI model was utilized to evaluate the performance of the developed PA system based on changes in the CBV pre- and post-ischemia at 800 nm (very close to the isosbestic point where the absorption of oxygenated and deoxygenated hemoglobin is identical) [ 29 ]. In Figure 7 A, representative photos of the targeted blood vessel over the right hemisphere pre- and post-PTI are shown.…”

“…The CBV was assumed to be proportional to the specific cortical region at 800 nm (very close to the isosbestic point where the absorption of oxygenated and deoxygenated hemoglobin is identical) [ 29 ]. In addition, the total hemoglobin concentration (HbT) and oxygen saturation (SO 2 ) were estimated by using two wavelengths (i.e., 750 nm and 850 nm), based on the optical absorption coefficient of hemoglobin at different wavelengths [ 29 ]: where µ a is the optical absorption coefficient; ε Hb and ε HbO2 are the molar extinction coefficients of Hb and HbO 2 , respectively; and [Hb] and [HbO 2 ] are the molar concentrations of Hb and HbO 2 , respectively [ 29 , 30 ]. For the maximum intensity projection (MIP) calculation, multiple B-scan images were first collected to form a 3D data set.…”

Photoacoustic imaging of kidney fibrosis for assessing pretransplant organ quality

“…Imaging of collagen phantoms, as well as imaging of mouse, pig, and human kidneys, was performed using the VevoLAZR-X system (Fujifilm VisualSonics Inc.) (56)(57)(58). This commercially available system uses an Nd:YAG laser 512 nm source through an optical parametric oscillator operating at 10 Hz pulse repetition frequency.…”

Insights into photoacoustic speckle and applications in tumor characterization

“…The prominence of this boundary “edge-effect” is strongly influenced by the transducer properties, system response and absorber concentration. Our group has demonstrated through simulations [23,29] and experiments [[30], [31], [32]] that the signals giving rise to speckle are dependent on the reconstruction approach, spatial distribution of PA sources and the bandwidth of the ultrasound detector.…”