Quantitative analysis of optical coherence tomography and histopathology images of normal and dysplastic oral mucosal tissues

Abstract

Selecting the most representative site for biopsy is crucial in establishing a definitive diagnosis of oral epithelial dysplasia. The current process involves clinical examination that can be subjective and prone to sampling errors. The aim of this study was therefore to investigate the use of optical coherence tomography (OCT) for differentiation of normal and dysplastic oral epithelial samples, with a view to developing an objective and reproducible approach for biopsy site selection. Biopsy samples from patients with fibro-epithelial polyps (n=13), mild dysplasia (n=2), and moderate/severe dysplasia (n=4) were scanned at 5-μm intervals using an OCT microscope and subsequently processed and stained with hematoxylin and eosin (H&E). Epithelial differentiation was measured from the rate of change (gradient) of the backscattered light intensity in the OCT signal as a function of depth. This parameter is directly related to the density of optical scattering from the cell nuclei. OCT images of normal oral epithelium showed a clear delineation of the mucosal layers observed in the matching histology. However, OCT images of oral dysplasia did not clearly identify the individual mucosal layers because of the increased density of abnormal cell nuclei, which impeded light penetration. Quantitative analysis on 2D-OCT and histology images differentiated dysplasia from normal control samples. Similar analysis on 3D-OCT datasets resulted in the reclassification of biopsy samples into the normal/mild and moderate/severe groups. Quantitative differentiation of normal and dysplastic lesions using OCT offers a non-invasive objective approach for localizing the most representative site to biopsy, particularly in oral lesions with similar clinical features.

Diffuse optical microscopy for quantification of depth-dependent epithelial backscattering in the cervix

“…We expect enhanced backscattering at high spatial frequencies in HSIL owing to the presence of more and enlarged nuclei in its superficial epithelium. In this respect, we seek to confirm the observation of depth-dependent epithelial backscattering as reported in 2012 by Adegun et al 33 using optical coherence tomography.…”

“…7(b) confirms the reported malignancy-related variation in depth-dependent epithelial backscattering. 33,50 In consequence, we study the ratio of epithelial backscattering at f ¼ 3 mm…”

“…20 Most cancers originate from epithelium, and, therefore, early detection of cancer by optical means must focus on the optical properties of superficial tissue layers. [23][24][25][26][27][28][29][30][31][32][33] Surface sensitivity can be obtained through polarization gated spectroscopy, 23 or single-and multifiber reflectance spectroscopy [24][25][26][27][28][29][30] including differential path length spectroscopy. 31 As a nondiffuse optical imaging modality, optical coherence tomography features high epithelial contrast 33 and represents another well-suited yet more expensive means for the detection of tissue microstructure.…”

Wide-field in vivo oral OCT imaging

“…Ex vivo studies have reported the ability of OCT to define cancer boundaries [6], and measure changes in tissue features associated with oral cancer diagnosis such as the thicknesses of the keratin layer, epithelial layer, and lamina propria, as well as identify the continuity of the basement membrane [7][8][9]. Quantitative analysis of the OCT attenuation coefficient in the epithelial layer of formalinfixed biopsy specimens has been employed to discriminate normal from mild, moderate and severe dysplasia with some success [10]. Several groups have performed in vivo oral cavity imaging to quantify epithelial thickness at different sites around the oral cavity [11,12], and identify tissue layers and microstructures [13].…”

In vivo wide-field reflectance/fluorescence imaging and polarization-sensitive optical coherence tomography of human oral cavity with a forward-viewing probe

“…Feasibility of OCT as a diagnostic tool has been demonstrated in various pre-clinical animal [24,25] and human [14,[26][27][28][29][30] oral cavity studies. Computational methods for automated OCT image analysis and classification [31], quantitative assessment [28,32] have been developed to aid diagnosis of oral cavity lesions. Polarization-sensitive OCT (PS-OCT) is an augmented OCT providing information of both structure and birefringence [33,34].…”