Advanced Imaging in the Diagnosis of Gastric Intestinal Metaplasia: The Expert's Approach

Abstract

Gastric intestinal metaplasia (IM) is associated with a risk for development of differentiated-type gastric cancers. The diagnosis of IM is currently based on the histology of biopsy specimens because IM usually appears in flat mucosa and has few morphologic changes, and identification of IM by conventional endoscopy has high interobserver variability and a poor correlation with histological findings. Autofluorescence imaging (AFI) produces real-time images from natural tissue fluorescence from endogenous fluorophores with light excitation. Narrow band imaging (NBI) uses two specific narrow banded lights (400–430 nm and 525–555 nm) to accentuate the contrast in surface structure and microvascular architecture of the superficial mucosa. With magnification, NBI enables a detailed observation of the morphological features of the epithelium corresponding to histology. Currently, AFI and NBI are incorporated with high-resolution white-light video endoscopy in one system (tri-modal imaging). To diagnose gastric IM, selection of Helicobacter pylori positive patients is important because it increases pretest probability. For an endoscopic procedure, areas with H. pylori associated mucosal atrophy or IM are identified as areas that increase visibility of mucosal vessels and lose gastric folds in the white-light image; greenish mucosa in the gastric corpus in AFI imagery; and whitish patchy areas in NBI imagery. When the magnifying NBI is applied in the areas, IM can be diagnosed as mucosa with ridged, papillary or villiform surface structure in the corpus or mucosa, with whitish papillary or villiform surface structure in the antrum, with the light blue crest sign (white-bluish lines of light on the epithelial crests). This article is part of an expert video encyclopedia.