Abstract

The heterogeneity of tissue can cause considerable errors in NIRS measurements, especially the presence of the non-scattering and clear CSF layer around the brain which strongly affects light propagation in the head. In this study the effect of scattering caused by arachnoid trabeculae in the otherwise clear CSF layer is investigated by Monte Carlo simulation. Results show that the presence of arachnoid trabeculae affects the total optical path length, a parameter which can be directly obtained by time resolved measurement. However, the partial optical path length in the brain, which relates the sensitivity of the NIRS signal to absorption changes in the brain is strongly affected by the CSF layer even if the light is scattered by the arachnoid trabeculae.

© 2000 Optical Society of America