Small separation diffuse correlation spectroscopy for measurement of cerebral blood flow in rodents.

Eashani Sathialingam,Erin M Buckley,Bharat Sanders,Courtney E Mccracken,Jaekeun Park,Seung Yup Lee,Leah Bryan

doi:10.1364/boe.9.005719

Abstract

Diffuse correlation spectroscopy (DCS) has shown promise as a means to non-invasively measure cerebral blood flow in small animal models. Here, we characterize the validity of DCS at small source-detector reflectance separations needed for small animal measurements. Through Monte Carlo simulations and liquid phantom experiments, we show that DCS error increases as separation decreases, although error remains below 12% for separations > 0.2 cm. In mice, DCS measures of cerebral blood flow have excellent intra-user repeatability and strongly correlate with MRI measures of blood flow (R = 0.74, p<0.01). These results are generalizable to other DCS applications wherein short-separation reflectance geometries are desired.

Highlights

Adequate cerebral blood flow (CBF) is critical for delivery of oxygen and nutrients necessary to maintain neuronal health and function
In this study, we explore the validity of diffuse correlation spectroscopy in small separation reflectance geometries
Kaplan et al demonstrated that Diffuse correlation spectroscopy (DCS) works best for slab thicknesses > 10 *, in the case of highly anisotropic scattering DCS can work for slab thicknesses as small as 3 * [37]

Summary

Introduction

Adequate cerebral blood flow (CBF) is critical for delivery of oxygen and nutrients necessary to maintain neuronal health and function. Abnormalities in blood perfusion are seen in numerous diseased states, including stroke [1,2], hemorrhage [3], traumatic brain injury [4,5], hypoxic-ischemia [6,7,8], and hypertension [9,10]. These abnormalities encompass significant reductions or elevations in flow, and vital impairments in the autoregulatory and neurovascular coupling mechanisms that regulate vascular tone [11,12,13]. While each technique certainly has its own advantages, numerous limitations remain, including the need for radioactive material (autoradiography), poor spatial resolution (LDF), low SNR (MRI), limited depth penetration (LSCI), and sensitivity to macrovascular blood flow velocity instead of microvascular blood flow (Doppler ultrasound)

Methods

Results

Discussion

Conclusion