Establishing diffuse speckle contrast signal relationship with blood flow

Abstract

Diffuse speckle contrast analysis (DSCA) measures blood flow in deep tissues by the sensitivity of speckle contrast signals to the displacement of red blood cells (RBCs). Currently, the most common model for describing the displacement of RBCs is a Brownian diffusion-like process. In fact, RBCs undergo shear-induced displacement in blood flow. In this paper, the reduction in speckle contrast due to shear-induced motions is studied by theory and Monte Carlo simulations. We provide the solution for the speckle contrast function in a semi-infinite geometry, and establish the quantitative relationship between speckle contrast and absolute blood flow in a realistic vascular network. Based on this relationship, we can determine the relative contributions of diffusive RBCs motions on the speckle contrast.