Monitoring refractive index variations in turbid media using phase-sensitive frequency-domain OCT

Functional imaging of clear and tissue-simulating phantoms using phase-resolved swept-source spectroscopic OCT (PhS-SSOCT) is described. Superior sensitivity of PhS-SSOCT technique to monitor ultra-small changes in sample refractive index is demonstrated using aqueous solutions of glucose and aqueous suspensions of polystyrene microspheres and glucose. Glucose-induced changes in the phase are found to be 0.039 rad/mM and 0.037 rad/mM in the 200 μm-thick cell for clear and turbid media, respectively, that is in good agreement with our previous data obtained using differential-phase time-domain OCT. Obtained results suggest that PhS-SSOCT has a potential for noninvasive, depth-resolved, real-time quantitative monitoring of concentrations of glucose and other analytes with high accuracy.