Advancements in endoscopic imaging for the detection of esophageal dysplasia and carcinoma

Advanced esophageal cancer, whether squamous cell or adenocarcinoma associated with Barrett's disease, carries a dismal prognosis. Dysplasia and early carcinoma, however, are amenable to surgery or endotherapy using techniques such as endoscopic resection, photodynamic therapy, and radiofrequency ablation. Therefore, the early detection of esophageal dysplasia and neoplasia is one of the most important goals of gastrointestinal endoscopy. This article will review several endoscopic imaging techniques and technologies that have been developed to enhance the visualization of mucosal glandular and vascular changes associated with early neoplasia, including the use of chromoendoscopy using vital dyes and stains. Also, reviewed in this article are endoscopic innovations that have received regulatory approval, are commercially available, and are supported by controlled clinical studies confirming their utility, such as high-resolution endoscopy and "virtual chromendoscopy" using narrow band imaging. The use of confocal laser endomicroscopy will be discussed, as this device provides real-time, histology-like information of cellular and vascular architecture. These technologies move us closer to the reality of an "optical biopsy," with a tissue biopsy diagnosis made in the gastrointestinal endoscopy unit. In addition to emphasizing the practical aspects of these techniques, this article will summarize other advanced imaging technologies that await regulatory approval, commercial availability, and clinical validation.