Experimental evaluation of angularly-variable fiber geometry for targeting depth-resolved reflectance from layered epithelial tissue phantoms

The aim of the present study focuses on experimentally demonstrating the efficacy of using angularly-variable fiber geometry to achieve the desired tissue-layer selection and probing depths with the further objective of enhancing the sensitivity and specificity of spectral diagnosis in stratified architectures that resemble human cervical epithelia. The morphological and biochemical features of epithelial tissue vary in accordance with tissue depths; consequently, the accuracy of spectroscopic diagnosis of epithelial dysplasia may be enhanced by probing the optical properties of this tissue. When correlated to cellular dysplasia, layer-specific changes in tissue optical properties may be deciphered by reflectance spectroscopy coupled with angularly-variable fiber geometry. This study addresses the utility of using such angularly-variable fiber geometry for resolving spatially-specific spectral signatures of tissue pathology. This is accomplished by interpreting and analyzing the reflectance spectra of increasingly dysplastic epithelial tissue in two-layer epithelial phantoms. Spectral sensitivity to tissue abnormalities in the epithelial layer is significantly improved as the obliquity of the collection fibers increases from 0 to 40 degrees. Conversely, conventionally orthogonal fibers are found to be more sensitive to changes in stromal tissue properties.