1. Department of Medicine, Section for Gastroenterology, Stord Helse-Fonna Hospital, Stord, Norway;
2. Department of Clinical Medicine, University of Bergen, Bergen, Norway;
3. Department of Medicine, National Centre for Functional Gastrointestinal Disorders, Haukeland University Hospital, Bergen, Norway;
4. Division of Gastroenterology, Department of Medicine Faculty of Medicine, GI Motility Research Unit, Chulalongkorn University, Bangkok, Thailand;
5. Thai Red Cross Society, King Chulalongkorn Memorial Hospital, Bangkok, Thailand;
6. Department of Medicine, National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen, Norway