Optical coherence tomography in turbid tissue: theoretical analysis and experimental results

Optical imaging of obscure structures in biological tissue can be accomplished by means of time-gated or coherence gated technique which enables effective rejection of multiple scattering from outside the small tissue volume of interest. However the mechanisms of these modalities differ according to our recent theoretical model: unlike the time-resolved technique, coherence-gated method traces out the local variations of the pathlength-resolved backscattering. In this paper, measurements on tissue scattering phantoms which provide apparent evidences in support of our model prediction are presented. Speckle-related effects are exhibited and analyzed. Some in vitro and in vivo tissue measurements are presented Monte-Carlo simulation is incorporated to provide pathlength-resolved reflectance in order to analyze OCT measurements. The results show that OCT is a promising means of detecting optical heterogeneity due to tissue microstructural differences.