In this longitudinal study, a mouse model of 4-nitroquinoline 1-oxide chemically induced tongue carcinogenesis was used to assess the ability of optical imaging with exogenous and endogenous contrast to detect neoplastic lesions in a heterogeneous mucosal surface. Widefield autofluorescence and fluorescence images of intact 2-NBDG-stained and proflavine-stained tissues were acquired at multiple time points in the carcinogenesis process. Confocal fluorescence images of transverse fresh tissue slices from the same specimens were acquired to investigate how changes in tissue microarchitecture affect widefield fluorescence images of intact tissue. Widefield images were analyzed to develop and evaluate an algorithm to delineate areas of dysplasia and cancer. A classification algorithm for the presence of neoplasia based on the mean fluorescence intensity of 2-NBDG staining and the standard deviation of the fluorescence intensity of proflavine staining was found to separate moderate dysplasia, severe dysplasia, and cancer from non-neoplastic regions of interest with 91% sensitivity and specificity. Results suggest this combination of noninvasive optical imaging modalities can be used in vivo to discriminate non-neoplastic from neoplastic tissue in this model with the potential to translate this technology to the clinic.
Current procedures for oral cancer screening typically involve visual inspection of the entire tissue surface at risk under
white light illumination. However, pre-cancerous lesions can be difficult to distinguish from many benign conditions
when viewed under these conditions. We have developed wide-field (macroscopic) imaging system which additionally
images in cross-polarized white light, narrowband reflectance, and fluorescence imaging modes to reduce specular glare,
enhance vascular contrast, and detect disease-related alterations in tissue autofluorescence.
We have also developed a portable system to enable high-resolution (microscopic) evaluation of cellular features within
the oral mucosa <i>in situ</i>. This system is a wide-field epi-fluorescence microscope coupled to a 1 mm diameter, flexible
fiber-optic imaging bundle. Proflavine solution was used to specifically label cell nuclei, enabling the characteristic
differences in N/C ratio and nuclear distribution between normal, dysplastic, and cancerous oral mucosa to be quantified.
This paper discusses the technical design and performance characteristics of these complementary imaging systems. We
will also present data from ongoing clinical studies aimed at evaluating diagnostic performance of these systems for
detection of oral neoplasia.