Establishing the quantitative relationship between diffuse speckle contrast analysis signals with absolute blood flow

Area of Science:

• Biomedical Optics
• Physiological Measurement
• Medical Imaging

Background:

• Diffuse speckle contrast analysis (DSCA) is used to measure blood flow in deep tissues.
• The sensitivity of DSCA relies on red blood cell (RBC) motion.
• A clear relationship between absolute blood flow (BF_abs) and the DSCA signal is currently lacking.

Purpose of the Study:

• To derive a quantitative relationship between BF_abs and the DSCA signal.
• To establish a linear connection between the slope of the speckle contrast function and BF_abs.
• To validate this relationship using simulations and explore its application in analyzing RBC motion contributions.

Main Methods:

• Derivation of a linear approximation function for speckle contrast, incorporating diffusive and advective RBC motions.
• Validation through Monte Carlo simulations of heterogeneous tissue models with varied vessel radii.
• Analysis of the derived linear relationship (k_slope vs. BF_abs).

Main Results:

• A linear relationship between the slope (k_slope) and absolute blood flow (BF_abs) was established.
• The derived model accounts for both shear-induced diffusive and correlated advective RBC motions.
• Monte Carlo simulations confirmed the feasibility of the quantitative relationship across different vascular parameters.

Conclusions:

• The study provides a novel quantitative framework for relating DSCA signals to absolute blood flow.
• This method enables the determination of relative contributions of diffusive RBC motion to speckle contrast reduction.
• The findings have implications for improved blood flow assessment in deep tissues with complex vascular structures.