Diagnostic Concordance Using Japan Narrow-band Imaging Expert Team Classification for Diagnosing Colorectal Neoplasms: A Web-based Diagnostic Concordance Study.

Objectives: The Japan Narrow-band Imaging Expert Team (JNET) classification is widely used for magnified endoscopic diagnosis of colorectal neoplasms. However, its diagnostic concordance, particularly among the core members who contributed to its development, has not been sufficiently evaluated. Therefore, this study aimed to assess the diagnostic concordance of the JNET classification among JNET core members using a web-based image interpretation test. Methods: A total of 27 JNET core members performed a web-based static image reading test in two separate sessions. Each image was classified according to the JNET criteria, and the diagnostic concordance rate (DCR) was analyzed. Cases were categorized as having high (≥80% consensus), moderate (70%-79% consensus), or low (<70% consensus) agreement. The impact of secondary findings on diagnostic classification was explored for the secondary analysis. Results: Agreement rates were significantly higher for sessile serrated lesions/hyperplastic polyps (SSL/HP) (>85%) than for neoplastic lesions. In the first session, the DCR for neoplastic lesions was substantially lower, with 54% for low-grade intramucosal neoplasia, 63% for high-grade intramucosal neoplasia/T1a, and 52% for T1b. The classification of T1b lesions showed notable variability. Further, while secondary findings influenced classification, this remained an exploratory analysis rather than a primary outcome. Conclusions: While the JNET classification demonstrated high diagnostic concordance for SSL/HP, variability remained in neoplastic lesions, particularly in T1b cancer. These findings highlight the need for further refinement of the classification system to improve its diagnostic concordance in clinical practice.