Meshed capillary vessels found on narrow-band imaging without optical magnification effectively identifies colorectal neoplasia: a North American validation of the Japanese experience.

Background: The presence of meshed capillary (MC) vessels is highly sensitive (96%) and specific (92%) for diagnosing colorectal neoplasia on colonoscopy by using narrow-band imaging (NBI) with optical magnification, which is not available in North America. However, the efficacy of NBI to identify an MC pattern without optical magnification has not been determined.

Objective: To determine the diagnostic capabilities of NBI colonoscopy without optical magnification in differentiating neoplastic from non-neoplastic colorectal polyps by using the MC pattern.

Design: Retrospective comparison of prospectively collected colorectal polyp data.

Setting: Large, academic medical center.

Patients: This study involved 126 consecutive colorectal polyps (median size 3 mm) that were found in 52 patients (33 men) with a median age of 59.5 years.

Intervention: All lesions identified by white-light colonoscopy were prospectively diagnosed in real-time by using the MC pattern as determined on high-definition NBI, with 1.5x zoom but without true optical magnification, and then endoscopically excised. Surgical pathology was used as the criterion standard.

Main Outcome Measurements: Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of identifying neoplastic polyps were calculated.

Results: NBI without optical magnification was found to have a sensitivity of 93%, specificity of 88%, positive predictive value of 90%, negative predictive value of 91%, and diagnostic accuracy of 91% when all polyp sizes were considered. For lesions < or =5 mm, sensitivity was 87%, specificity was 93%, positive predictive value was 89%, negative predictive value was 91%, and diagnostic accuracy was 90%.

Limitations: Single-center, single-endoscopist experience.

Conclusion: Use of the MC pattern on NBI colonoscopy without optical magnification effectively distinguishes neoplastic from non-neoplastic colorectal polyps. NBI colonoscopy without optical magnification for neoplastic polyp diagnosis appears to be comparable with NBI with optical magnification when the MC pattern is used. A large, prospective trial is needed for further validation.