Modern laser speckle contrast theory: flaws and consequences
Embargo Date
2020-06-03
OA Version
Citation
Abstract
Laser speckle contrast imaging (LSCI) is a non-invasive optical imaging technique
for monitoring blood flow in brain, skin, and retina. The simple and cheap instrument
makes it a promising technology for both clinical applications and research. Modern
LSCI theory takes advantage of the relation between blood flow and the speckle contrast
v ~ 1/K^2 to provide an online acquisition of a full-field blood flow image. However,
the assumptions about the form of field correlation function, static scattering
effect, and the coherence factor make interpretation of the contrast imprecise. Here
we examined how the assumptions in modern LSCI theory affect the relative blood
flow measurement and utilized Dynamic Laser Speckle Imaging (DLSI) to validate
the imprecision of modern LSCI. Most importantly, the contrast models for measuring
relative flow in the brain parenchyma and the large vessels were derived. It turns out
that modern LSCI underestimates blood flow change and leads to significant error for
slow blood flow measurement.