title: In vivo measurement of non-keratinized squamous epithelium using a spectroscopic microendoscope with multiple source-detector separations.
abstract: In the non-keratinized epithelia, dysplasia typically arises near the basement membrane and proliferates into the upper epithelial layers over time. We present a non-invasive, multimodal technique combining high-resolution fluorescence imaging and broadband sub-diffuse reflectance spectroscopy (sDRS) to monitor health at various tissue layers. This manuscript focuses on characterization of the sDRS modality, which contains two source-detector separations (SDSs) of 374 μm and 730 μm, so that it can be used to extractin vivooptical parameters from human oral mucosa at two tissue thicknesses. First, we present empirical lookup tables (LUTs) describing the relationship between reduced scattering (μs') and absorption coefficients (μa) and absolute reflectance. LUTS were shown to extract μs' and μawith accuracies of approximately 4% and 8%, respectively. We then present LUTs describing the relationship between μs', μaand sampling depth. Sampling depths range between 210-480 and 260-620 μm for the 374 and 730 μm SDSs, respectively. We then demonstrate the ability to extractin vivoμs', μa, hemoglobin concentration, bulk tissue oxygen saturation, scattering exponent, and sampling depth from the inner lip of thirteen healthy volunteers to elucidate the differences in the extracted optical parameters from each SDS (374 and 730 μm) within non-keratinized squamous epithelia.
authors.affiliation: Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA 72701.
authors.forename: Gage J
authors.initials: GJ
authors.lastname: Greening
authors.affiliation: Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA 72701.
authors.forename: Narasimhan
authors.initials: N
authors.lastname: Rajaram
authors.affiliation: Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, USA 72701.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Muldoon
keywords: diffuse; human; microendoscopy; optical; oral; phantoms; properties; reflectance; spectroscopy