Recognition and characterization of small colonic neoplasia with high-definition colonoscopy using i-Scan is as precise as chromoendoscopy

BackgroundThe EPKi system (Pentax, Japan) enables resolution above HDTV. Aim of the study was to test the efficacy of HD+ alone and with the new post-processing digital filter i-Scan or chromoendoscopy (Methylene blue 0.1%) in screening for colorectal cancer. We focused on lesions less than 5 mm as a surrogate marker for the optical possibilities of the EPKi system.MethodsThe last 30 cm of the colon in a screening population were inspected with HD+ alone, in combination with i-Scan (2:1 randomisation) and subsequently with chromoendoscopy.All lesions were characterized and targeted biopsies were performed.Resultsi-Scan augmented in 69 patients the identification of lesions from 176 to 335 (p < 0.001) and chromoendoscopy to 646 (p < 0.001). The additional lesions were mainly flat (type IIb, 74%), which were only recognized using i-Scan or chromoendoscopy. The amount of neoplasias was not significantly different (HD+: 5, i-Scan: 11, Chromoendoscopy: 11), but all could correctly be predicted using i-Scan or chromoendoscopy.ConclusionsHD+ colonoscopy with and without i-Scan unmask a plethora of small lesions but chromoendoscopy can even advance the number. However, i-Scan was able to predict neoplasia as precisely as chromoendoscopy and might shortly replace chromoendoscopy as a more time efficient tool.