Effective use of the Japan Narrow Band Imaging Expert Team classification based on diagnostic performance and confidence level

Figure 1 Narrow Band Imaging International Colorectal Endoscopic classification¹. ¹Can be applied using colonoscopes with/ without optical (zoom) magnification. ²These structures (regular or irregular) may represent the pits and the epithelium of the crypt opening. ³In the WHO classification, sessile serrated polyp and sessile serrated adenoma are synonymous. ⁴Type 2 consists of Vienna classification types 3, 4 and superficial 5 (all adenomas with either low or high grade dysplasia, or with superficial submucosal carcinoma). The presence of high grade dysplasia or superficial submucosal carcinoma may be suggested by an irregular vessel or surface pattern, and is often associated with atypical morphology. SSP: Sessile serrated polyp.

Figure 2 The Japan Narrow Band Imaging Expert Team classification. ¹If visible, the caliber in the lesion is similar to surrounding normal mucosa. ²Micro-vessels are often distributed in a punctate pattern and well-ordered reticular or spiral vessels may not be observed in depressed lesions. ³Deep submucosal invasive cancer may be included.

Figure 3 Flow diagram of study selection.

Figure 4 Treatment strategy of colorectal lesions using the Japan Narrow Band Imaging Expert Team classification. ¹Any polyps suspected of SSPs should be resected by endoscopic treatment. ²Hyperplastic polyps less than 5mm in size are commonly left in situ. HP: Hyperplastic polyp; SSP: Sessile serrated polyp; LGIN: Low grade intramucosal neoplasia; HGIN: High grade intramucosal neoplasia; S-SMC: Shallow submucosal invasive cancer; D-SMC: Deep submucosal invasive cancer; LC: Low confidence.