1. Division of Gastroenterology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross, Bangkok, Thailand
2. Center of Excellence for Innovation and Endoscopy in Gastrointestinal Oncology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
3. Department of Medicine, Buddhachinaraj Hospital, Phitsanulok, Thailand
4. Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand