1. Digestive Endoscopy Unit, ASST Niguarda, Milan, Italy
2. Gastroenterology Unit, Azienda Ospedaliera Santi Antonio e Biagio e Cesare Arrigo, Alessandria, Italy
3. Digestive Endoscopy Unit, Fondazione Policlinico Gemelli IRCCS, Rome, Italy
4. CERTT, Center for Endoscopic Research Therapeutics and Training, Catholic University, Rome, Italy