Contributions of diffuse and directed flow in turbid media to absolute measurements of tissue perfusion and oxygen consumption using laser speckle and spatial frequency domain imaging

We describe the development of a perturbation-free technique to measure tissue blood flow and metabolic rate of oxygen (MRO2) using LSI and SFDI. Analytical (diffusion) and computational (Monte Carlo) models are employed to characterize the contributions of diffuse and directed flow to the measured speckle contrast. Measured flow data is combined with the deoxygenated hemoglobin concentration and a path-length factor (both obtained from SFDI) to model tissue oxygen consumption in units of M O2/min. The results of this model were comparable with values of MRO2 measured with other imaging methods (PET, MRI/MRS).