Background: This study aimed to evaluate a three‐dimensional endoscopic ultrasonographic (3‐D EUS) system in the assessment of the tumor invasion depth of early gastric carcinoma.

Methods: Sixty‐nine macroscopically early cancer lesions in 67 patients were recruited in an in vivo study. The surgically resected gastric specimens of 30 of them were re‐examined in an ex vivo study. An Olympus 3‐D EUS imaging system was employed in both studies. Diagnostic accuracy for tumor invasion depth was evaluated and compared with histopathological sections stained by H&E and Masson’s trichrome stain. Reconstructed surface‐rendering images were evaluated and compared with the endoscopic and macroscopic findings.

Results: Three‐dimensional EUS allowed rapid tomographic assessment of the lesions in both the in vivo and ex vivo studies. The accuracy of 3‐D EUS for the assessment of tumor invasion depth was 87% in the in vivo study. The accuracy rate was significantly lower (P = 0.03) for the cancer lesions associated with ulcer fibrosis (74%) than for those with no fibrosis (97%). In the 30 subjects who underwent both studies, the accuracy rates were higher in the ex vivo than the in vivo study (94%vs 77% for all the lesions, and 93%vs 74% for cancers associated with fibrosis), but were not statistically significant. The rates of good surface‐rendering images were 64% and 94% in the in vivo and ex vivo studies, respectively. The differences were attributed to the clearer dual‐plane reconstruction images obtained in the ex vivo study in absence of motion artifacts.

Conclusions: Three‐dimensional EUS is a promising imaging technique for the assessment of tumor invasion depth of early gastric cancer.