Fluctuations of temporal contrast in laser speckle imaging of blood flow

Laser speckle contrast imaging can be used to estimate changes in blood flow velocity in either the spatial or temporal domain. Temporal speckle contrast analysis provides higher spatial resolution than spatial speckle contrast does. However, owing to limitations of the statistical sample size in practical applications, the speckle contrast obtained consistently fluctuates around an accurate value. It is important to reveal the quantitative relationship between the statistical sample size and fluctuations of temporal speckle contrast. In this Letter, we present a new model for temporal speckle contrast that accounts for the effects of statistical size owing to the finite frames of the speckle images used for temporal analysis. Furthermore, an expression for estimating the fluctuations of temporal speckle contrast is derived. Both phantom and animal experiment results support our theoretical model. (C) 2018 Optical Society of America