Detection of Blood Flow Speed in Shallow and Deep Tissues Using Diffuse Correlation Spectroscopy
Mikie Nakabayashi, Yumie Ono
Vol. 6 (2017) p. 53-58
Diffuse correlation spectroscopy (DCS) is an emerging optical technique for noninvasive measurement of hemodynamics of living tissues. Using emitter and detector optical probes attached to the body surface, DCS estimates the mean speed of blood flow in the tissue, through which the emitted near-infrared light propagates (blood flow index: BFI). The advantage of DCS is that the mean blood flow in deeper tissues such as muscle layers can be measured noninvasively. To investigate the sensitivity of DCS in detecting the physiological changes of blood flow in deep and shallow tissues, we measured the blood flow speed in 14 healthy participants during a reactive hyperemia test and skin temperature changes. In the reactive hyperemia test, blood flow returned to the steady state faster in deep tissues than in shallow tissues, and temperature-dependent reallocation of local blood flow in shallow and deep tissues was clearly observed. These results demonstrate that DCS can measure the differences in physiological blood flow 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.