White Light, TXI, NBI and Computer-Aided Detection for Recurrence at Post-EMR Scars (PRINCESS)

Large colorectal polyps removed piece by piece (piecemeal endoscopic mucosal resection) can recur at the resection scar. Detecting this residual or recurrent tissue at surveillance colonoscopy is essential, because it can then be treated endoscopically. Recurrence can be subtle, and the best way to examine the scar has not been established. This study compares four ways of examining post-polypectomy scars: high-definition white light endoscopy (WLE) texture and color enhancement imaging (TXI, Olympus) narrow-band imaging (NBI, Olympus) an artificial intelligence computer-aided detection system (GI Genius, Medtronic) Each scar is examined with all four techniques, in random order. A different expert endoscopist performs each technique, without knowing the findings of the others. Biopsies are then taken from every scar, and any suspicious tissue is removed. Histology is the reference standard. The main goal is to determine which technique, or combination of techniques, has the highest sensitivity and negative predictive value for detecting recurrence.

Inclusion Criteria: * Age 18 years or older. * Previous endoscopic resection (endoscopic mucosal resection or endoscopic submucosal dissection) of a colorectal lesion ≥15 mm, performed 3 to 6 months before the surveillance colonoscopy. * Histology of the resected lesion showing an adenoma or a sessile serrated lesion. * Referral for endoscopic review of the post-polypectomy scar. * Signed written informed consent. Exclusion Criteria: * Resected lesion \