Comparative OCT imaging of human esophagus: How well can we localize the muscularis mucosae?

Early diagnosis with esophageal cancer limited to the mucosa will allow for local endoscopic treatment and improve prognosis. We compared with histology OCT images of healthy human esophageal tissue from two systems operating at 800 and 1275 nm to investigate which wavelength was best suited for detailed OCT imaging of the esophageal wall, and to localize the muscularis mucosae. Within an hour of surgical resection, an esophageal specimen was cleaned of excess blood and soaked in formalin for a minimum of 48 hours. In order to precisely localize the different layers of the esophageal wall on an OCT image, well-defined structures within the esophageal wall were sought. Following OCT imaging the specimen was prepared for routine histology. We observed that our 1275 nm system with 12 μm resolution was superior in terms of penetration. As compared to histology, the 4 μm resolution of our 800 nm system made fine details more visible. Using either system, a minimally trained eye could recognize the muscularis mucosae as a hypo-reflective layer. Although different conditions may apply in vivo, our ex vivo study paves the path to precise interpretation of OCT images of the esophageal wall.