Recognition accuracy of tumor extent using a prototype 3D endoscope for superficial gastric tumor: an ex vivo crossover study.

Background and study aims Many studies have shown the utility of rigid three-dimensional (3D) endoscopes in surgery, but few have reported the utility of flexible 3D endoscopes. This ex vivo study was intended to investigate whether a newly developed 3D endoscope (GIF-Y0083; Olympus) improves diagnostic accuracy for superficial gastric tumor. Methods Twelve observers comprising experts, trainees, and novices (4 each) evaluated 2D and 3D images of 20 specimens resected by gastric ESD. Evaluation items were diagnostic accuracy of tumor extent and degree of confidence in assessing (a) tumor extent, (b) morphology, and (c) comprehensive recognition. The 2D and 3D endoscopy data were compared in a crossover analysis. Results Overall, diagnostic accuracy was significantly higher with 3D images (88.1%) than with 2D images (84.2%) (P<0.01). Comparison by skill level showed that 3D images significantly improved diagnostic accuracy among novices but not among experts or trainees. Comparison by morphology showed that diagnostic accuracy did not differ significantly for type IIa/IIb lesions but improved significantly for type IIc lesions among trainees and novices. Overall, 3D images significantly increased the degree of confidence in the assessment of all three items (a-c). Comparison by skill level showed similar results, and comparison by morphology showed that regardless of skill level, the degree of confidence in assessing all items (a-c) increased significantly only when examining type IIc lesions. Conclusion Compared with 2D images, 3D images significantly improved both diagnostic accuracy of tumor extent and degree of confidence for diagnosing superficial gastric tumor. The utility of the 3D endoscope was apparent among trainees and novices and for the diagnosis of type IIc lesions.