Validation of the NICE Classification Using Pentax Chromoendoscopy

All lesions will be evaluated using the 3 i-scan modes and the 2 OE modes without magnification. The lesion size data, location and macroscopic shape of the lesions based on the Paris classification will be recorded. Finally all lesions will be classified in real-time into 3 types based on NICE classification (NICE 1, hyperplastic polyps; NICE 2, adenoma and superficial submucosal carcinoma; NICE 3, SM-d invasive carcinoma). A level of confidence (high or low) will be assign in each stage. Polyp's images will be photographically and videotape recorded. All polyps will be resected or biopsied for histopathological examination used as the criterion standard for the analysis.