Endoscopy: Image-Enhanced Endoscopy Focused on JNET Classification—Narrow-Band Imaging (NBI)

Fig. 3.1

The NBI International Colorectal Endoscopic (NICE) classification

Table 3.1

Performance characteristics of the NICE classification for high-confidence prediction

	NICE 1 vs. 2	NICE 2 vs. 3
Prediction	Adenoma	Deep submucosal invasive cancer
Rater, n	Experts, 2	Medical students, 5
Polyps (n)	236	400
Evaluation	Real time during colonoscopy	Still images
Performance, % (95% CI)
Accuracy	89 (83–93)	90 (85–93)
Sensitivity	98 (94–100)	92 (87–95)
Specificity	69 (55–80)	88 (84–92)
PPV	87 (80–92)	88 (83–91)
NPV	95 (84–99)	92 (87–95)
HC rate, %	75	50

The NICE classification has been established by the international experts and disseminated across the world as the classification can easily be applied without optical magnification. However, there remain some issues regarding the NICE classification. First, sessile serrated polyp (SSP) was not included in the NICE classification, because the standard histopathological diagnostic criteria for SSP were not fully established. Second, NICE 2 category includes two types of polyp: benign low-grade adenomas and submucosal invasive cancer with malignant behavior. These two types should be diagnosed individually in terms of selecting an appropriate treatment strategy. The former should be treated by polypectomy or piecemeal resection; however the latter should be treated by en bloc deep resection such as EMR or ESD to examine accurate depth of cancer invasion which is necessary for judgment of curative or non-curative resection. Therefore, the Japanese endoscopists decided to separate the type 2 category into type 2A (low-grade adenoma) and type 2B (high-grade adenoma and submucosal cancer) by using the advantage of magnifying endoscopy and developed the JNET classification as an advanced version of the NICE classification.

3.3 The Japan NBI Expert Team (JNET) Classification (Fig. 3.2)

In 2011, Sano et al. organized the Japan NBI Expert Team (JNET) consisting of 38 members, mainly specialists of colonoscopy in Japan, to unify four coexisting magnifying NBI classifications (Sano, Hiroshima, Showa, and Jikei) [3, 8–10]. Firstly, we designed a common evaluation criteria of vessel pattern and surface pattern, called NBI scale. This scale was divided into four categories: type 1 predictive of hyperplastic lesions/sessile serrated polyp, type 2A of low-grade intramucosal neoplasia (LGIN), type 2B of high-grade intramucosal neoplasia (HGIN)/shallow submucosal invasive cancer (S-SMC), and type 3 of deep submucosal invasive cancers (D-SMC) (Fig. 3.3).