Laser speckle based quantitative estimation of blood flow and decorrelation time analysis in vivo

Abstract

This dissertation discusses the application of laser speckle for making the laser speckle-based blood flow imaging quantitative in the animal model. Also, applying laser speckle for quantify the speed of wavefront decorrelation for light focusing in the deep tissue. Until now speckle imaging techniques are semi-quantitative. We demonstrate a novel optical speckle image velocimetry (OSIV) technique for measuring the quantitative blood flow vector map by utilizing particle image velocimetry with speckle cross-correlations. We applied OSIV to image the blood flow in a mouse brain, and as a proof of concept, imaged the real-time dynamic changes in the cortical blood flow field during the stroke process in vivo. Our wide-field quantitative flow measurement OSIV method without the need of tracers provides a valuable tool for studying the healthy and diseased brain. In the second part, we will discuss about the scattering dynamics in the mouse brain in vivo via multispeckle diffusing wave spectroscopy (MSDWS) using a custom fiber probe that simulates a point-like source within the brain, we investigate the relationship between this decorrelation time and the depth of the light source inside the living mouse brain at depths up to 3.2 mm.