Background and Aims: Endocytoscopy (EC) enables real-time histopathological evaluation through two modes: narrow-band imaging endocytoscopy (EC-NBI) and staining-based endocytoscopy (EC-SB). However, the comparative diagnostic accuracy between EC-NBI and EC-SB, and their performance of endoscopists with varying levels of experience remains unclear.

Methods: This retrospective study analyzed 565 colorectal lesions from 433 patients. Both expert and non-expert endoscopists evaluated colorectal lesions based on EC-NBI and EC-SB images. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), and inter- and intra-observer agreement were compared with histopathological diagnoses.

Results: The sensitivity, specificity, and accuracy for diagnosing hyperplastic polyps by experts using EC-SB are 93.0%, 98.0%, and 97.0%, which were significantly higher than the results of EC-NBI (86.8%, 96.1%, and 94.2%, respectively; P < 0.05 for all). Similarly, for diagnosing adenomas to intramucosal cancers, EC-SB by experts achieved significantly higher sensitivity, specificity and accuracy (93.0%, 94.8% and 93.6%) compared to EC-NBI (90.2%, 90.1% and 90.2%, respectively; P < 0.05 for all). In addition, for diagnosing invasive cancers, EC-SB by experts showed significantly higher specificity (98.7% vs. 96.1%, P < 0.05).

Conclusions: EC-SB demonstrated higher diagnostic accuracy for colorectal lesions among experts, supporting its utility for precise treatment decisions.