Detection of Blood Flow Speed in Shallow and Deep Tissues Using Diffuse Correlation Spectroscopy

Abstract

Diffuse correlation spectroscopy (DCS) is an emerging optical technique for noninvasive measurement of hemo-dynamics of living tissues. Using emitter and detector optical probes attached to the body surface, DCS estimates the mean speed of blood ow in the tissue, through which the emitted near-infrared light propagates (blood ow index: BFI). The advantage of DCS is that the mean blood ow in deeper tissues such as muscle layers can be measured noninvasively. To investigate the sensitivity of DCS in detecting the physiological changes of blood ow in deep and shallow tissues, we measured the blood ow speed in 14 healthy participants during a reactive hyperemia test and skin temperature changes. In the reactive hyperemia test, blood ow returned to the steady state faster in deep tissues than in shallow tissues, and temperature-dependent reallocation of local blood ow in shallow and deep tissues was clearly observed. These results demonstrate that DCS can measure the differences in physiological blood ow dynamics in deep and shallow tissues, suggesting the potential use of DCS to noninvasively quantify changes at microcirculation level in both shallow and deep tissue layers. Keywords: diffuse correlation spectroscopy, blood ow speed, reactive hyperemia test, thermoregulatory control of blood ow. Adv Biomed Eng. 6: pp. 53-58, 2017.