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In Vivo Blood Viscosity Characterization Based On Frequency-Resolved Photoacoustic Measurement

Y Zhao1,2*, S Yang2 , Y Wang3 , Z Yuan3 , L Liu2 ,J Qu2, L Xiang1 , (1) University of Oklahoma, Norman, OK (2) Shenzhen University, Shenzhen, China (3) University of Macau, Macau, China


(Sunday, 7/14/2019)  

Room: ePoster Forums

Purpose: Disturbed microcirculation is often involved in major diseases before they become clinically evident. Viscosity is one of the most important mechanical and physiological indexes in clinical diagnosis. A comprehensive understanding of blood viscosity will not only provide a potential early perspective on the origin and progression of such diseases but also prove critical information for medical or surgical treatment as well as evaluating the ef�cacy of therapeutic interventions. In this letter, we presented a frequency-resolved photoacoustic measurement for noninvasively blood viscosity characterization in subcutaneous microvasculature.

Methods: A solid-state laser operating at 532 nm with a 10Hz frequency was used as the excitation source. The PA signal was captured by the customized ultrasonic transducer with the center frequency of 75MHz. All data were sent to a computer to be stored and analyzed with the fast Fourier transform by MATLAB computation. Then, the full width half maximum (FWHM) of the PA frequency spectrum can be obtained to characterize the viscosity of the sample. The two-dimensional PA images were obtained by mechanically scanning the sample over the desired region.

Results: We deduced the process of PA effect on the basis of thermal viscosity theory and a negative correlation was shown between the viscosity coef�cient and the FWHM of the PA frequency spectrum. Water mixed with different concentrations of glycerol was measured to test the feasibility and accuracy of this method. FWHM of the PA frequency spectrum was also obtained in vivo in the mouse ear to characterize the blood viscosity from different vessel bifurcations, and the metabolism-induced viscosity changes were dynamically monitored in the microvasculature.

Conclusion: Experimental results demonstrate that this technique can realize the real-time monitoring of the morphology and viscosity changes of the subcutaneous microvasculature, which indicated an attractive prospect in visualizing, understanding, and assessment of the pathological progression.


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