Laser Speckle contrast imaging (LSCI) is a non-invasive or minimally invasive method for visualizing blood flow and perfusion in biological tissues. In LSCI the motion of scattering particles results in a reduction in global and regional speckle contrast. A variety of parameters can affect the calculated contrast values in LSCI techniques, including the optical properties of the fluid and surrounding tissue. In typical LSCI where the motion of blood is of interests, optical properties are influenced by hematocrit levels. In this work we considered the combined effects of both the scattering and absorption coefficients on LSCI measurements on a flow phantom. Fluid phantoms consisting of various concentrations of neutrally buoyant ~10 micron microspheres and India ink mixed with DI water were formulated to mimic the optical properties of whole blood with various levels of hematocrit. In these flow studies, it was found that an increase in μa and/or μs led to a decrease in contrast values when all other experimental parameters were held constant. The observed reduction in contrast due to optical property changes could easily be confused with a contrast reduction due to increased flow velocity. These results suggest that optical properties need to be considered when using LSCI to make flow estimates.

Date Published: 5 March 2015
PDF: 4 pages
Proc. SPIE 9322, Dynamics and Fluctuations in Biomedical Photonics XII, 93220U (5 March 2015); doi: 10.1117/12.2077260

Published in SPIE Proceedings Vol. 9322:
Dynamics and Fluctuations in Biomedical Photonics XII
Valery V. Tuchin; Kirill V. Larin; Martin J. Leahy; Ruikang K. Wang, Editor(s)