Photoacoustic Doppler flow measurement in optically scattering media

Abstract

We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microcirculation with high sensitivity.

‘Go with the flow ’: A review of methods and advancements in blood flow imaging

“…By employing techniques such as diffraction-limited optical focusing (OR-PAM) [297], resolution improvements on the order of 5 mm or greater are obtainable. The PA Doppler (PAD) effect [298][299][300] is the combination of the production of an acoustic wave from a light-absorbing medium and the shifting of this wave when it has a motion relative to a detector. Consider a light absorbing-particle suspended in a liquid is moving at a velocity v and an intensity-modulated laser beam illuminates the particle at an angle a.…”

Perturbation to Symmetry and Adiabatic Invariants of General Discrete Holonomic Dynamical Systems

“…Luo [34] gave another new type of adiabatic invariants called the Lutzky adiabatic invariants lately. These studies further inspire interests in research about adiabatic invariants [35][36][37].…”

M-mode photoacoustic particle flow imaging

“…Previously, we have demonstrated photoacoustic Doppler flow measurement [13]. In this Letter, we report another photoacoustic flow measurement method called M-mode photoacoustic particle flow imaging.…”

“…This imaging modality has been demonstrated as a powerful tool for studying microvascular structures in deep tissue [10] as well as for monitoring blood hemoglobin oxygenation in microvessels [11]. Recently, there is also growing interest in developing photoacoustic blood flow measurements [12,13]. Because of the advantage in imaging depth as well as the high photoacoustic signal contrast produced by RBCs or exogenous light-absorbing particles relative to surrounding tissue, when applied to microcirculation study, photoacoustic flow measurement is expected to be able to alleviate the hindrance of the aforementioned methods.…”