The use of narrow-band imaging (NBI) to predict histology of diminutive polyps (≤5 mm) might be ready to be incorporated into clinical practice, say the authors of a recent study.

Diminutive colorectal polyp. Courtesy of C. Hassan.

The American Society for Gastrointestinal Endoscopy (ASGE) has set specific criteria that new technologies must meet before they can be accepted into clinical practice for predicting surveillance and histology of small polyps. “Only a few studies have attempted to assess whether NBI-based polyp prediction satisfies the required ASGE criteria, with controversial and sometimes incomplete results,” explain Alessandro Repici and Cesare Hassan, two authors of the study.

To rectify this problem Repici, Hassan and co-workers performed a prospective, multicentre study to assess whether NBI meets the ASGE criteria. 278 patients were enrolled in the study and 574 polyps <10 mm were characterized by endoscopists and then retrieved for histological analysis. Each polyp prediction was assigned a high or low level of confidence by the endoscopist. The main outcome measure was the accuracy of high-confidence NBI prediction for polyps <5 mm in predicting surveillance intervals and histology.

The results of the study are encouraging. The negative predictive value of high-confidence NBI for predicting polyp histology was 92%. “Our study showed in a multicentre setting that it is possible to use NBI-based criteria to assign post-polypectomy surveillance intervals and to decide which polyps are to be removed,” say Repici and Hassan. Incorporating this technology into clinical practice could potentially reduce costs associated with post-polypectomy pathological examinations.

One limitation of the study is that only experienced endoscopists were included. “We need to see whether the expert-based results are reproducible in a community setting,” the researchers conclude.