Absorbance of opaque microstructures in optically diffuse media

In this study experimental measurements are used to determine that the observed absorbance of opaque microstructures in optically diffuse media correlates with the total surface area rather than the attenuation as calculated in a nonscattering environment. The data suggest that it may be possible to use remote measurements of optical diffuse transmission to quantify surface areas of microcapillaries that are highly absorbing or larger blood vessels that can have high intrinsic attenuation because of hematocrit alone. Results obtained in a transmission geometry are insensitive to the position of the microstructure along the line between source and detector, whereas those collected in a remission geometry are highly sensitive to the depth at which the structure is located. These types of measurement involving microscopic structures embedded in diffuse media have potential application in quantifying blood vessel surface areas that contain contrast agents or other microparticles within tissue. © 2001 Optical Society of America.