Fig. 1

Example of useful case and useless case. a Reddish flat lesion with small ulcer is shown at the lesser curvature of the body by conventional endoscopy; b After dying indigo carmine and acetic acid, the DL became more clearly (this image scored 8, and classified to useful case); c A normochromic protruded lesion is shown at the posterior wall of the antrum by conventional endoscopy, and the DL can be recognized as the rising portion of the protruded lesion; d After dying indigo carmine and acetic acid, the DL seems to be not obviously improved (this image scored 4, and classified to useless case)