Multispectral optical imaging for the detection and delineation of oral neoplasia
Roblyer, Darren Michael
Richards-Kortum, Rebecca Rae
Doctor of Philosophy
Despite the accessibility of the oral cavity to inspection, patients with oral cancer most often present at a late stage, leading to high morbidity and mortality. Multispectral widefield optical imaging has emerged as a promising technology to aid clinicians in screening and resection of oral neoplasia, but current approaches rely on subjective interpretation. This work focuses on the design, construction, and clinical testing of a novel multispectral widefield optical imaging device for objective screening and delineation of oral neoplasia. The Multispectral Digital Microscope (MDM) acquires in vivo images of oral tissue in autofluorescence, narrow band reflectance, and orthogonal polarized reflectance modes that the diagnostic value of each modality may be qualitatively and quantitatively evaluated alone and in combination. Using in vivo imaging data collected from 56 patients and 11 normal volunteers, combined with computer aided diagnostics, a sensitivity of 100% and a specificity of 91.4% was achieved for discriminating oral dysplasia and cancer from normal tissue in an independent validation set. A single feature calculated from the autofluorescence images at 405 nm excitation was used to achieve this performance. Disease probability maps were constructed using this feature to help identify areas with a high probability of abnormality. Autofluorescence imaging at 405 nm excitation also provided the greatest image contrast which was significantly higher than that using standard white-light illumination. Features extracted from other imaging types did not appear to aid in diagnosis. Ex vivo image data from the MDM was combined with image data from a high-resolution microendoscope (HRME) in order to determine if a synergistic relationship existed between these devices. The ability to objectively diagnose oral lesions substantially increased when using both devices in combination compared to using either alone. This combination of devices provides a practical means of screening the entire mucosal surface for suspicious regions, using the MDM, and then using the HRME for confirmation of diagnosis. This work has demonstrated that widefield autofluorescence imaging at 405 nm excitation can be highly effective for the objective discrimination of oral lesions.