Fiber optic confocal microscope: in vivo precancer detection
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Cancer is a significant public health problem worldwide. Many cancers originate as precancerous lesions in the epithelium which, when removed in sufficient time, can prevent progression to cancer. However, current detection techniques are typically timeconsuming and expensive, limiting their acceptance and accessibility. Optical techniques, such as confocal microscopy, have significant potential to provide clinicians with real-time, high-resolution images of cells and tissue without tissue removal. These images of cell morphology and tissue architecture can be used to characterize tissue and determine the presence or extent of precancer and cancer. This dissertation explores the instrumentation and application of fiber optic reflectance confocal microscopy for in vivo precancer detection. The first part of the dissertation presents in vivo imaging of suspicious lesions in the human uterine cervix and oral mucosa using a fiber bundle based confocal microscope with a complex glass miniature objective lens. Images are analyzed quantitatively and qualitatively to determine the potential of this technology in vivo. An analysis of nuclear density from vii images of 30 cervical epithelium sites shows differentiation between normal and precancerous sites. Similarly, images from 20 oral mucosa sites demonstrate changes in nuclear density and tissue architecture indicative of progression of precancer and cancer. In addition to this multi-fiber confocal microscope used with a glass objective lens for the clinical studies, imaging of tissue samples has been accomplished with the same confocal system using an injection molded plastic miniature objective lens demonstrating comparable optical quality for a significantly less expensive optical component. Finally, a benchtop prototype of a single fiber confocal microscope using a gimbaled two-axis MEMS scanner has been designed and constructed. Imaging of a resolution target and cellular samples demonstrates sufficient resolution and field of view for cellular imaging. The results from the imaging studies presented here indicate that in vivo confocal microscopy has the potential to improve early precancer detection in epithelial tissue. Advances in imaging technology will continue to reduce the cost of imaging systems and improve the imaging capability, leading to an inexpensive, real-time, minimally-invasive tool for in vivo imaging.