Fig. 5

Milestone 3: Cartoon illustration of the advantage of PS-OCT over conventional OCT using the example of subepithelial fibrosis of esophageal tissue (as in EoE). a and b depict histologic sections, c and d OCT intensity scans, and (e) and (f) OCT local phase retardation (a measure of birefringence) images of two pathologically different stages (healthy vs. fibrosis). While the OCT intensity scan of the fibrotic tissue region may not allow quantification of subepithelial collagen, the PS-OCT image clearly outlines the fibrotic area and even allows for quantitative birefringence evaluation. g and h depict swine esophagus images acquired by an endoscopic PS-OCT system ex vivo, showing the layered structures of epithelium and lamina propria/muscularis mucosa. Intensity (g) as well as accumulated phase retardation (h) are shown, respectively (figure and caption adapted and reprinted with permission from [83] © The Optical Society)