Objective validity of the Japan Narrow‐Band Imaging Expert Team classification system for the differential diagnosis of colorectal polyps

Abstract

Background and Aim The Japan Narrow‐Band Imaging (NBI) Expert Team (JNET) classification is a recently proposed NBI magnifying endoscopy‐based classification system for colorectal tumors. Although the usefulness of this system has been reported by JNET experts, its objective validity remains unclear. We tested its validity and usefulness for the diagnosis of colorectal polyps by including colonoscopy experts and non‐experts as test participants. Methods Forty NBI images of polyps of various JNET types were shown to 22 doctors (11 experts and 11 non‐gastrointestinal [GI] trainees) who had not examined the patients. The doctors diagnosed the polyps based solely on the surface and vessel patterns in the magnified images and the JNET classification system. Concordance rates of their diagnoses with the pathological findings of the polyps were determined, and the results for experts and non‐GI trainees were compared. Results Both for colonoscopy experts and non‐GI trainees, the JNET classification system was particularly useful for classifying polyps as benign or malignant. Although the accuracy rates for classifying polyps into each JNET type varied among colonoscopy experts, those who were familiar with the JNET classification system were able to diagnose polyps with approximately 90% accuracy. Common mistakes were attributable to misunderstandings of the wording in the JNET classification chart and lack of proper training. Conclusion The JNET classification system is a practical approach for the diagnosis of colorectal polyps. Training is required even for experienced colonoscopists to adopt the system properly. Common pitfalls must be shared among colonoscopists to improve the accuracy of the diagnosis.

Improving assessment and management of large non-pedunculated colorectal lesions in a Western center over 10 years: lessons learned and clinical impact

“…In our cohort, we confirm that after complete ER, a recurrence may be found in almost one-quarter of patients, but is endoscopically manageable in the majority of cases. Even if our median endoscopic follow-up was relatively short (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)), data from the literature are reassuring because 96 % of recurrences occur within 6 months after index resection, and only 2 % of recurrences can be expected after 12 months [34], as also suggested by our median time-to-recurrence of 7 months (IQR 4-13). Our multivariate analysis identified independent predictors of recurrence, both known (PM vs EB resection) and poorly reported (grading of dysplasia and involvement of "risky hotspots").…”

“…Irregularity in superficial pit/vascular pattern seems to be the strongest SMI predictor. However, JNET classification was not available for all lesions, and published experiences have demonstrated that interobserver agreement is suboptimal, with specific training required to reach acceptable accuracy [21,31,32]. This could suggest that if the endoscopist has sufficient training/experience with pit/ vascular pattern interpretation, this should be the most considered parameter, along with presence of pseudodepression.…”

“…Morphology and superficial pattern were extracted from the databases and all images and videos were reevaluated by agreement of four trained endoscopists unaware of histology. Each lesion was categorized using JNET classification [21,22] for vascular pattern and one modified Paris classification [23] [23] (PD) was furthermore independently dichotomised as present/ absent. As for lesion size, an endoscopic estimate initially was used as a reference, but was subsequently systematically compared to the histopathological report, with any significant disagreement leading to lesion exclusion.…”

“…Morphology and superficial pattern were extracted from the databases and all images and videos were reevaluated by agreement of four trained endoscopists unaware of histology. Each lesion was categorized using JNET classification 21 22 for vascular pattern and one modified Paris classification 23 , to further include sessile lesions (sessile [S]; sessile with pseudodepression [S-PD]; LST granular, homogeneous [LST-GH] or mixed [LST-GM]; LST non-granular, flat-elevated [LST-NG-FE] or pseudodepressed [LST-NG-PD]). Pseudodepression 23 (PD) was furthermore independently dichotomised as present/absent.…”

Magnification endoscopy in combination with acetic acid enhancement and narrow-band imaging for the accurate diagnosis of colonic neoplasms

“…Conventional white-light endoscopy (WLE) is a fundamental modality, but magnification endoscopy is not necessarily globally used due to a requirement for technical expertise. Magnification chromoendoscopy with crystal violet staining (CV-MCE) enables visualization of the pit pattern (the shape of the glandular crypt opening) [3][4][5], and magnification endoscopy with narrow-band imaging (NBIME) enables visualization of the vessel pattern without mucosal staining [6][7][8]. Generally, magnification endoscopy is considered to be superior to WLE for the qualitative diagnosis of colorectal polyps, but it has not been investigated fully.…”