Optical molecular imaging in the gastrointestinal tract.

Recent developments in optical molecular imaging allow for real-time identification of morphologic and biochemical changes in tissue associated with gastrointestinal neoplasia. This review summarizes widefield and high-resolution imaging modalities in preclinical and clinical evaluation for the detection of colorectal cancer and esophageal cancer. Widefield techniques discussed include high-definition white light endoscopy, narrow band imaging, autofluoresence imaging, and chromoendoscopy; high-resolution techniques discussed include probe-based confocal laser endomicroscopy, high-resolution microendoscopy, and optical coherence tomography. New approaches to enhance image contrast using vital dyes and molecular-specific targeted contrast agents are evaluated.