Optical Coherence Tomography of Barrett’s Esophagus

Objectives

The endoscopic diagnosis of specialized intestinal metaplasia (Barrett’s esophagus) and dysplasia can be surprisingly difficult, especially when only short lengths of Barrett’s esophagus are suspected. Various imaging techniques have been used to aid the endoscopic diagnosis of Barrett’s esophagus and the staging of early neoplasia, including endoscopic ultrasound, magnification endoscopy, and the application of chemical stains and pigments to alter tissue appearances (i. e. chromoendoscopy). The ultimate goals of these advanced imaging methods are to: (i) detect intestinal metaplasia in the background of gastric metaplasia of the esophagus; (ii) detect foci of dysplasia and early neoplasia in the background of intestinal metaplasia; and (iii) distinguish early invasive carcinoma from mucosal dysplasia. Increasing amounts of data are available on the use of endoscopic optical coherence tomography (OCT) to aid in the diagnosis and classification of Barrett’s esophagus and associated dysplasia. OCT is a cross-sectional imaging technique that provides the highest endoscopic resolution currently available and produces images to a depth of a few millimeters. The in vivo resolution of OCT imaging (∼ 10 µm) is more than ten times greater than that of high-frequency ultrasound and has the potential to visualize subcellular structures including nuclei. OCT is analogous to ultrasound but uses light waves rather than acoustic waves.

OCT provides images in real time with a resolution approaching that found in conventional histopathology, but without the need for tissue removal; thus it is termed “optical biopsy”. The resolution of OCT allows visualization of the different layers of gastrointestinal epithelium and has been demonstrated to reliably distinguish Barrett’s epithelium from normal gastric and squamous mucosa. Preliminary data also suggest that OCT may be useful in detecting dysplasia in Barrett’s esophagus. Although still in its infancy as a clinical tool, OCT has great potential in the study of the presence and natural history of Barrett’s esophagus.

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