Current status of narrow-band imaging magnifying colonoscopy for colorectal neoplasia in Japan.

The narrow-band imaging system can be used to examine the microvascular architecture and surface pattern on the mucosal surface with high sensitivity. The clinical significance of NBI observation is summarized as follows: (1) differential diagnosis of hyperplasia, adenoma, and carcinoma; (2) diagnosis according to the presence of a surface pattern as an alternative to magnifying endoscopic observation with dye spraying, and (3) determination of the invasion depth of an early colorectal carcinoma. However, at present, many NBI magnifying observation classifications for colorectal tumor exist in Japan. To internationally standardize the NBI observation criteria, a simple classification system is required. On the basis of these backgrounds, an international cooperative group (Colon Tumor NBI Interest Group - CTNIG) has developed a simple category classification (NICE classification: NBI International Colorectal Endoscopic Classification) which classifies NBI findings into types 1-3.