Background: Gastric intestinal metaplasia (GIM) is a premalignant condition of gastric cancer. The gold standard for GIM diagnosis is histology. GIM are scattered and focally located. Random biopsy is quite cumbersome and takes hours, thus targeted biopsy by endoscopic guidance is recommended. However, the diagnostic accuracy of conventional white light endoscopy is low due to sampling error and high inter-observer variability. Narrow band imaging with magnification endoscopy (NBI-ME) can be applied for more accurate targeted biopsy. However there is little data about the diagnostic accuracy of this technique.
Aim: To define the diagnostic accuracy of GIM detection by NBI-ME
Methods: Thirty eight patients with previously diagnosed as GIM by random biopsy were enrolled. NBI-ME (Olympus GIF Q160Z) with targeted biopsy for both positive and negative lesions from six areas (4 and 2 from antrum and incisura respectively) was done according to three endoscopic criteria including light blue crests (LBC), villous pattern (VP) and large long crests (LLC). All magnified images were interpreted by the other three gastroenterologists and the results were analyzed and compared to the pathological results. The specimens were read based on the updated Sydney classification by one pathologist.
Results: There were 85 of the 228 specimens with proven positive for GIM. The average accuracy, sensitivity, specificity, positive predictive value, and negative predictive value by using all three criteria were 73.10%, 66.67%, 76.92%, 63.38%, 79.50% respectively. The calculated Kappa score from all three interpreters was 0.83. When using each criterion, LBC provided the highest diagnostic accuracy. Importantly, early gastric cancers including one intestinal type and one signet ring cell adenocarcinoma were detected in two patients. Conclusion: NBI-ME possesses a high accuracy with perfect agreement for GIM detection. LBC has the highest accuracy over VP and LLC. However, if all three criteria are used, the sensitivity and NPV improve. Thus NBI-ME might be useful for follow-up and early detection of early cancerous progression of patients with GIM.