1. The Intervention Centre , Oslo University Hospital - Rikshospitalet , Pb. 4950 Nydalen, 0424 , Oslo , Norway
2. Institute of Clinical Medicine, Faculty of Medicine , University of Oslo , Oslo , Norway
3. Department of HPB Surgery , Oslo University Hospital - Rikshospitalet , Rikshospitalet , Norway
4. Department of Gastrointestinal Surgery , Akershus University Hospital , Lørenskog , Norway