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Narrow-band imaging for scar (NBI-SCAR) classification: from conception to multicenter validation

Lookup NU author(s): Professor Alastair BurtORCiD


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© 2019 American Society for Gastrointestinal EndoscopyBackground and Aims: Surveillance post–endoscopic resection (ER) currently warrants biopsy samples from the resection site scar in most cases, although clinical practice is variable. A classification with standard criteria for scars has not yet been established. We aimed to create and validate a novel classification for post-ER scars by using specific criteria based on advanced imaging. Methods: Key endoscopic features for scars with and without recurrence were (1) dark brown color, elongated/branched pit pattern, and dense capillary pattern and (2) whitish, pale appearance, round/slightly large pits, and irregular sparse vessels. Scars were first assessed with high-definition white-light endoscopy (HD-WLE) followed by interrogation with narrow-band imaging (NBI). Scars with at least 2 concordant characteristics were diagnosed with “high confidence” for NBI for scar (NBI-SCAR) classification. The final endoscopic predictions were correlated with histopathology. The primary outcome was the difference in sensitivity between NBI-SCAR and HD-WLE predictions. Secondary outcomes included the validation of our findings in 6 different endoscopy settings (Australia, United States, Japan, Brazil, Singapore, and Malaysia). The validation took place in 2 sessions separated by 2 to 3 weeks, each with 10 one-minute videos of post-ER scars on underwater NBI with dual focus. Inter-rater and intrarater reliability were calculated with Fleiss’ free-marginal kappa and Bennett et al. S score (as discussed below in a similar case) S score, respectively. Results: One hundred scars from 82 patients were included. Ninety-five scars were accurately predicted with high confidence by NBI-SCAR in the exploratory phase. NBI-SCAR sensitivity was significantly higher compared with HD-WLE (100% vs 73.7%, P <.05). In the validation phase, similar results were found for endoscopists who routinely perform colonoscopies and use NBI (sensitivity of 96.4%). The inter-rater and intrarater reliability throughout all centers were, respectively, substantial (κ =.61) and moderate (average S =.52) for this subset. Conclusions: NBI-SCAR has a high sensitivity and negative predictive value for excluding recurrence for endoscopists experienced in colonoscopy and NBI. In this setting, this approach may help to accurately evaluate or resect scars and potentially mitigate the burden of unnecessary biopsy samples.

Publication metadata

Author(s): Zorron Cheng Tao Pu L, Chiam KH, Yamamura T, Nakamura M, Berzin TM, Mir FF, Hourneaux de Moura EG, Madruga Neto AC, Koay DSC, Loong CK, Ovenden A, Edwards S, Burt AD, Hirooka Y, Fujishiro M, Singh R

Publication type: Article

Publication status: Published

Journal: Gastrointestinal Endoscopy

Year: 2019

Volume: 91

Issue: 5

Pages: 1146-1154

Print publication date: 01/05/2020

Online publication date: 05/09/2019

Acceptance date: 20/08/2019

ISSN (print): 0016-5107

ISSN (electronic): 1097-6779

Publisher: Mosby Inc.


DOI: 10.1016/j.gie.2019.08.036

PubMed id: 31494134


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