The overall objective of this study is to obtain data to evaluate whether high-resolution imaging of the gastrointestinal mucosain vivo can assist clinicians in detecting dysplastic (precancerous) areas. This is an exploratory study of a confocal endoscope designed to evaluate the feasibility of using this FDA-approved device in the endoscopic surveillance of subjects at high-risk for neoplasia in the upper and lower GI tract. The confocal endoscope provides real-time in vivo microscopic images of the mucosa which resemble standard pathology.