Optical Detection of a Capillary Grid Spatial Pattern in Epithelium by Spatially Resolved Diffuse Reflectance Probe: Monte Carlo Verification

We performed a large scale Monte Carlo verification of possibility of detecting the capillary grid spatial pattern in surface tissues such as mucosal epithelium or epidermis with very thin (optically nonsignificant) stratum corneum by a spatially resolved diffuse reflectance probe. Our results confirm the hypothesis that a spatially resolved, steady-state, diffuse reflectance spectroscopy can potentially identify absorption inhomogeneities located at the depth of 0.5-1.0 of the transport mean free path l_s´ = 1/μ_s´, which is the range of capillary loops locations within epithelium. The modulation depth depends significantly on an inhomogeneity´s absorption, depth of the inhomogeneity, a bulk reduced scattering coefficient, and the size of the defect. The optical clearing technique can be used to lower the scattering in surface tissues and subsequently increase the transport mean free path, which can lead to increase in the sensitivity of the method.