Background: The benefits of narrow band imaging (NBI) for improving the detection rate of colorectal polyps remain unclear. New generation NBI using the 290 system (290-NBI) provides an at least two-fold brighter image than that of the previous version. We aimed to compare polyp miss rates between 290-NBI colonoscopy and high-definition white light endoscopy (HDWL). Methods: In total, 117 patients were randomized to undergo either 290-NBI or HDWL from June 2015 to February 2017. In the HDWL group, we performed HDWL as an initial inspection, followed by a second inspection with NBI. In the 290-NBI group, NBI was performed as the initial inspection, followed by a second inspection with HDWL. We compared polyp and adenoma detection rates and polyp miss rates (PMR) between the two groups and analyzed the factors associated with the PMR. Results: In total, 127 polyps were detected in the 117 patients. No differences in adenoma or polyp detection rates were observed between the two groups. The PMR for 290-NBI was 20.6% and that for HDWL was 33.9% (p = .068). However, the non-adenomatous PMR for 290-NBI was significantly lower than that of HDWL (11.5% vs. 52.2%, p = .002). Furthermore, the miss rates of polyps on the left side of the colon, flat-type polyps, and non-adenomatous polyps were significantly lower in the 290-NBI than HDWL. Conclusions: New generation NBI may reduce PMR, especially of flat-type and non-adenomatous polyps and those on the left side of the colon. (UMIN000025505).
Keywords: Narrow band imaging; miss rate; polyp.