Post written by Takeshi Shimizu, MD, from the Department of Gastroenterology, Sendai City Medical Center, Sendai, Japan.

The focus of our study was to identify the ideal acetic acid (AA) concentration for AA-enhanced narrow-band imaging (NBI) magnifying endoscopy (ANBI-ME) in diagnosing colorectal epithelial neoplasms. We then compared its pit pattern diagnostic ability and diagnostic concordance with crystal violet (CV)–staining magnifying endoscopy (CV-ME) at that concentration.

CV has potential carcinogenic risks, increasing the need for alternatives to CV-ME. The optimal AA concentration for ANBI-ME in colorectal neoplasms remained unclear. Because colorectal endoscopy lacks aspiration risk, higher AA concentrations are feasible. Evaluating different concentrations could help identify the ideal option for enhancing magnifying observation and pit pattern diagnosis.

We tested AA at 1.5%, 2.25%, 3.0%, and 4.5%. Although diagnostic accuracy remained high (89%-97%) across concentrations, only at 4.5% did we achieve a kappa value of 0.82, indicating excellent agreement with CV-ME. Higher concentrations extended the whitening duration without increasing peristalsis or adverse events, suggesting 4.5% is both effective and safe.

In an additional comparison of 4.5% ANBI-ME with CV-ME, we observed high diagnostic concordance, and diagnostic performance was similarly robust between the 2 methods.

To further validate these findings, we are conducting a prospective study comparing the diagnostic performance of 4.5% ANBI-ME and CV-ME in a cohort with a high proportion of Japan NBI Expert Team type 2B lesions, where NBI magnification alone struggles to determine invasion depth.

This study demonstrated that the ideal AA concentration for ANBI-ME, which is considered a potential alternative to CV-ME, is 4.5%. If further prospective studies strengthen the evidence, ANBI-ME may be established as a useful modality to replace CV-ME.

Images of pit patterns with the use of cetic acid–enhanced narrow-band-imaging magnifying endoscopy (ANBI-ME) and crystal violet–stained magnifying endoscopy (CV-ME).

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