This study is a clinical validation of our developed a computer-aided optical dignosis of advanced adenoma using non-magnified NBI image. This study is a randomized clinical trial comparing endoscopists' optical recognition of advanced adenoma for sending to histological examination with our computer-aided system. The hypothesis of the study is that the developed computer-aided system increases the percent of sending actual advanced adenoma Intelligence Assisted Optical Diagnosis of Advanced Adenomas

Colorectal polyp diagnosis is based on endoscopic resection and histological analysis. An accurate optical diagnosis could avoid histological lesion of smaller lesions, reducing the costs associated with histological diagnosis. However, it should be noted this policy could only be applied in diminutive polys considering high proposition of advanced adenomas in polyps more than 5 mm. In addition, optical diagnosis criteria of advanced adenomas have not been validated for finding advanced adenomas among adenoma polyps. If as many as advanced adenomas as possible could be differentiated from non-advanced adenomas and be further sent for histological examination, this policy could be generalized to small polyps.

Considering this situation, the investigators tried to develop computer-aided optical dignosis of advanced adenoma using non-magnified NBI image with preliminary, satisfied results. In this study, the investigators next validate the investigators' developed computer-aided system for detecting advanced adenomas by comparing endoscopists' optical detection of advanced adenomas with or without the investigators' computer-aided system.

Inclusion Criteria:

• Endoscopists with NBI experience

Exclusion Criteria:

• Endoscopists without colonoscopy and NBI experience