Low-cost high temporal resolution diffuse correlation spectroscopy (Conference Presentation)

Abstract

Diffuse correlation spectroscopy (DCS) is an optical method for non-invasive measurements of blood flow in deep tissue microvasculature, such as the brain, without the need for tracers or ionizing radiation. The technique relies on determining temporal autocorrelations of light intensity fluctuations which arise due to time changing speckle patterns of moving scatterers when illuminated by a long coherence length laser. Measurements of blood flow using DCS have extensively been validated and have found some clinical translation already. High temporal resolution by fast sampling of the autocorrelation curves has recently been achieved by software based correlators. Here we demonstrate a new software correlator approach which uses components that are an order of magnitude cheaper than current approaches. We will present on the instrument design, as well as measurements of pulsatile blood flow on healthy volunteers. We will show blood flow measurements with a signal bandwidth of 50Hz and present on signal to noise ratios (SNR) of extracted pulse waveforms as a function of sampling rate. We will show how using an EKG based timing of the signal for averaging increases the fidelity of extracting the blood flow waveform even in low SNR environments. We will further present results of the pulsatile waveforms and the latency of the dicrotic notch as affected by posture changes in healthy volunteers.