Multidistance diffuse correlation spectroscopy for simultaneous estimation of blood flow index and optical properties

Abstract

Abstract. Traditionally, diffuse correlation spectroscopy (DCS) measures microvascular blood flow by fitting a physical model to the measurement of the intensity autocorrelation function from a single source-detector pair. This analysis relies on the accurate knowledge of the optical properties, absorption, and reduced scattering coefficients of the medium. Therefore, DCS is often deployed together with diffuse optical spectroscopy. We present an algorithm that employs multidistance DCS (MD-DCS) for simultaneous measurement of blood flow index, as well as an estimate of the optical properties of the tissue. The algorithm has been validated through noise-free and noise-added simulated data and phantom measurements. A longitudinal in vivo measurement of a mouse tumor is also shown. MD-DCS is introduced as a stand-alone system for small source-detector separations (<2 cm) for noninvasive measurement of microvascular blood flow.

Assessment of a multi-layered diffuse correlation spectroscopy method for monitoring cerebral blood flow in adults

“…The multidistance data were then analyzed with a three-layered solution to the correlation diffusion equation to account for light propagation through scalp, skull and brain, and the different blood flows in scalp and brain [26]. Rather than fitting a complete autocorrelation curve, different ranges of correlation times were used to fit the curves obtained at the two sourcedetector distances in order to alter the weighting to shorter or longer photon pathlengths [23,39]. More specifically, the range for the longer SDD (27 mm) was restricted to early correlation times, while longer correlation times were selected for the shorter SDD (20 mm).…”

Tissue Optics and Photonics: Light-Tissue Interaction

“…A fundamental difference of diffusion wave spectroscopy (DWS) compared to the QELS spectroscopy is that this approach is applicable in the case of dense media with multiple scattering, which is very important for tissues [5,52,53,61]. It is assumed thereby that due to multiple scattering the each photon that has reached given observation point of the detector experiences a great number of scattering events N (Fig.…”

“…The spatial distribution of contrast of a dynamic speckle pattern at its time-integration can be employed as a detecting parameter to provide a full-field velocity measuring technique [5,[46][47][48][49][50][51][52][53][54][55]. If the integration time is comparable with the period of the intensity fluctuations caused by dynamic light scattering, the effect of coherent light interaction with a RPS will be a blurring of the recorded speckle pattern -a reduction in the speckle contrast.…”

“…Speckle temporal dynamics gives information about intensity fluctuations connected with Brownian motion of biological molecules or flow of the blood particles. This is the basis for diffusion wave spectroscopy (DWS) or diffusion wave imaging (DWI) [5,52,53,61].…”

“…Scattering of light by movable particles is called dynamic light scattering in contrast to scattering of light by none movable or static particles, which is called static or elastic scattering as it occurs without energy transfer [5,9,[43][44][45][46][47][48][49][50][51][52][53][54][55][56]60]. Instead, at scattering by a movable particle small but measurable light energy change occurs, thus dynamic light scattering is often called as a quasi-elastic light scattering (QELS).…”