In vivo layer-resolved characterization of oral dysplasia via nonlinear optical micro-spectroscopy

Abstract

Optical spectroscopy has proven to be a powerful technique for studying neoplastic transformation in epithelial tissue. Since specific intra-layer precancerous changes originate in the stratified layers of the oral mucosa, layer-resolved analysis will likely improve both our understanding of the mechanism of premalignant transformation, and clinical diagnostic outcomes. However, the native fluorescence signal in linear spectroscopy typically originates from a multi-layered focal volume. In this study, nonlinear spectroscopy was exploited for in vivo layer-resolved discrimination between normal and dysplastic tissue for the first time. Our results revealed numerous intra-layer specific differences.

Advances and challenges in label-free nonlinear optical imaging using two-photon excitation fluorescence and second harmonic generation for cancer research

“…[108] found redox ratio calculated inversely as NADH/FAD to be increased in cancerous colonic biopsies and malignant cell lines respectively. In vivo studies conducted by Walsh et al in mouse xenograft models for breast cancer [109] and Edward et al in oral cancer models in hamsters [90] also showed similar findings. However a rare exception would be the work of Kirkpatrick et al [29] where the redox ratio (equated as FAD/FAD + NAD(P)H) was found to be increased in high-risk normal tissue and even higher in cancerous ovarian biopsies, as compared to low-risk normal tissues.…”

“…In an in vivo study conducted by Edward et al [90] they observed the normal oral cavity in the hamster to have symmetrically shaped autofluorescence spectra with an emission peak at 515 nm. On the other hand, they observed asymmetric shaped autofluorescence spectra in the dysplastic regions induced by chemical carcinogenesis in hamster oral cavity.…”

“…In vivo auto fluorescent emission spectra of stratum corneum in normal oral cavity as compared to moderate and severe dysplasia of the oral cancer model in hamster (excitation wavelength = 780 nm). The emission peak of normal region in oral cavity lies at 515 nm, while the emission peak of the dysplastic region is 'blueshifted' to 480 nm [90]. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)…”

Depth Resolved Differences After Corneal Crosslinking With and Without Epithelial Debridement Using Multimodal Imaging

“…Images were captured using a modified Zeiss confocal laser scanning microscope (LSM 410; Zeiss, Oberkochen, Germany) allowing for SHG microscopy. 22 A near infrared femtosecond laser consisting of a Tsunami Ti:sapphire laser pumped by a frequency doubled Nd:YVO at 532 nm (Spectra Physics, Irvine, CA) served as the illumination source for SHG microscopy. The excitation source for confocal microscopy was an argon/ krypton ion laser capable of providing 488, 568, and 647 nm illuminations.…”

Nonlinear optical microscopy and microspectroscopy of oral precancers and early cancer

“…The multiphoton microscopy system used for these studies has been reported previously [1] with the modification for microspectroscopy also reported [9]. Illumination for multiphoton autofluorescence excitation was by a Tsunami Ti: Sapphire femtosecond (~100fs, 82MHz) laser (Spectra-Physics, CA) and directed through ultrafast optics into a Zeiss 410 confocal microscope modified for multiphoton microscopy.…”