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Screening and surveillance recommendations for patients with Barrett esophagus (BE) are based on the assumption that this condition is premalignant. Given the poor survival statistics for patients with esophageal cancer, the goal of BE surveillance is early recognition of dysplasia and neoplasia. For detection of specialized intestinal metaplasia (SIM) and dysplasia within the esophagus, researchers have relied on chromoendoscopy using various dyes. Recently, attention has turned to enhanced biomedical optics, including narrow-band imaging (NBI). NBI changes the optical filters of the standard videoendoscope and uses high-intensity blue light to image superficial tissue structures, emphasizing capillary and mucosal patterns. The authors of two recent studies evaluated the clinical usefulness of NBI in patients with known or suspected BE.
One Dutch group performed a single-center study of NBI plus magnifying endoscopy in 63 patients. This dual technique had a sensitivity of 94%, a specificity of 76%, a positive predictive value (PPV) of 64%, and a negative predictive value of 98% for identifying mucosal characteristics of SIM and high-grade dysplasia (HGD).
A U.S. group performed a single-center, prospective cohort study of 51 patients. Histology was assessed in blinded fashion and then correlated with NBI images. The sensitivity of this strategy for detecting SIM with HGD was 100%, the specificity was 98.7%, and the PPV was 95.3%. No HGD was missed when biopsies were limited to areas with identified irregular or distorted mucosal or vascular patterns characteristic of HGD. NBI was not helpful in distinguishing areas of SIM with low-grade dysplasia.
Kara MA et al. Detection and classification of the mucosal and vascular patterns (mucosal morphology) in Barrett’s esophagus by using narrow band imaging. Gastrointest Endosc 2006 Aug; 64:155-66.
Sharma P et al. The utility of a novel narrow band imaging endoscopy system in patients with Barrett’s esophagus. Gastrointest Endosc 2006 Aug; 64:167-75.
Comment
Both groups demonstrated the practical, technical advantage of NBI for targeting biopsies in the inspection of mucosal morphology in BE patients. This technique is an alternative to chromoendoscopy, with specific advantages over that technique. In chromoendoscopy, complete and even coating of the mucosa and accurate identification of vascular patterns through the dye stain are problematic. A dye spray catheter is required. In NBI, a particular endoscope and processor are necessary; thus, a cost is also incurred for endoscopists who want to employ this technique.
Mastering these techniques likely will involve a learning curve, an issue these studies did not evaluate. Better detection of HGD in surveillance of BE is clearly needed. These results suggest that NBI will be an extremely useful advance in that direction.