4. I-scan with High Definition colonoscope (group F) This technique involves a PENTAX EC3890Fi colonoscope that is CE approved and commercially available. The procedure involves a normal white light endoscopy during progression of the scope. Once the caecum is reached the entire procedure will be performed in the TE- modus (Tissue enhancement mode) with surface enhancement on medium (range low-medium-high). This has no influence or side effects for the patients because the c- modus is switched on by pushing a button on the scope.