Sub-diffuse optical biomarkers characterize localized microstructure and function of cortex and malignant tumor.

This study uses a sub-diffusive light transport model to analyze fiber-optic measurements of reflectance spectra to recover endogenous tissue biomarkers and to correct raw fluorescence emissions for distortions from background optical properties. Measurements in tissue-simulating phantoms validated accurate recovery of the reduced scattering coefficient [(0.3-3.4  mm^-1), error 10%], blood volume fraction [(1-3 vol%), error 7%], and a dimensionless metric of anisotropic scattering, γ, that is sensitive to submillimeter tissue ultrastructure [(1.29-2.06), error 11%]. In vivo sub-diffusive optical data acquired during clinical neurosurgeries characterize differences in microstructure (γ), perfusion (blood volume), and metabolism (PpIX fluorescence) between normal cortex and malignant tumor.