Quantitative blood flow velocity imaGinG

Laser speckle flowmetry suffers from a debated quantitative relationship with blood flow, velocity or tissue perfusion and a lack of calibration of the inverse relationship 1/τc = αV between decorrelation time (τc) and flow velocity (V). Using a modified microcirculation imager, we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions based on the scattering phase function, within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that laser speckle flowmetry offers a quantitative measure of flow velocity in addition to vessel morphology, providing the quantification of local blood flow, velocity and tissue perfusion for clinically relevant applications. Adapted from: A. Nadort, K. Kalkman, T. G. van Leeuwen, and D. J. Faber, "Quantitative blood flow velocity imaging using laser speckle flowmetry" (in submission). Quantitative Laser speckLe contrast imaging 59 4 4.