Multiexposure laser speckle contrast analysis system calibration limited by perfusion-dependent scattering on the skin

Abstract

Significance: Application of multiexposure speckle contrast imaging (MESI) methods for perfusion measurements can correct for the contribution of static scattering of the skin, at the expense of reduced temporal resolution as compared to classical single-exposure methods. Persistence of tissue scattering properties during the measurements could allow for an initial calibration and enhancement of the temporal resolution of the measurements.

Aim: We aim to study the influence of the perfusion on the light scattering of the forearm skin and to use the obtained data for the enhancement of the temporal resolution.

Approach: A wide range of skin perfusion states was induced while monitoring the changes in the dynamic range of the exposure-dependent contrast. Different measurement and evaluation methods were tested based on an initial MESI calibration followed by image recording with reduced number of exposure time values.

Results: The changes in the skin perfusion can alter not only the contribution of the static scattering to the speckle images but also the short-exposure time contrast limit.

Conclusions: The perfusion-dependent scattering of the skin can invalidate the precalibrations (e.g., $\beta$ calibration) characterizing the combination of the given tissue and the measurement system.

Keywords: laser speckle contrast analysis; light scattering; skin perfusion; speckle imaging.