1. National Centre for Functional Gastrointestinal Disorders, Haukeland University Hospital, Bergen, Norway
2. National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen, Norway
3. Department of Clinical Medicine, University of Bergen, Bergen, Norway
4. Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
5. Institute of Clinical Sciences, University of Bergen, Bergen, Norway