Diagnostic accuracy and interobserver agreement for prediction of gastric preneoplastic lesions with fourth-generation endocytoscopy: Pilot study.

[BACKGROUND AND STUDY AIMS] Early detection of gastric preneoplastic lesions (GPL) is essential to prevent gastric cancer. Endocytoscopy may improve optical diagnosis through in vivo histologic assessment of mucosa. We assessed diagnostic performance of endocytoscopy and interobserver agreement for GPL diagnosis compared with reference histopathology.

[PATIENTS AND METHODS] Eighty gastric areas (36 antrum, 44 corpus) from 25 prospectively recruited patients were assessed by endocytoscopy and classified as non-preneoplastic, preneoplastic, or dysplastic/neoplastic by an expert endoscopist. Targeted biopsies from each area served for histopathological assessment. High-quality images/videos were recorded for independent review by three additional observers (1 expert, 2 non-experts), blinded to endoscopic and histological findings.

[RESULTS] Histologically, 25 gastric areas (31.3%) showed GPL, 14 (17.5%) atrophic gastritis, and 11 (13.8%) intestinal metaplasia. Gastric cancer was found in three cases (3.8%). Combined sensitivity, specificity, and accuracy for endocytoscopic diagnosis of GPL or dysplasia were 89.3%, 94.2%, and 92.5% among expert endocytoscopists and 85.7%, 68.3%, and 74.4%, among non-experts, respectively. Interobserver agreement was substantial (κ-value 0.79) between experts and fair (κ-value 0.30) between non-experts.

[CONCLUSIONS] New-generation endocytoscopy has potential to identify GPL with high diagnostic accuracy, reliability, and reproducibility. Training and clinical experience with endocytoscopy are required to maximize diagnostic performance.