1 Department of Anesthesiology and Intensive Care, Section of Pain Management, Oslo University Hospital, Rikshospitalet, Norway Hospital for Rehabilitation, Stavern, Vestfold Hospital Trust, Norway The Interventional Centre, Oslo University Hospital, Rikshospitalet, Norway Department of Radiology, Oslo University Hospital, Rikshospitalet, Norway Oslo University Hospital, Rikshospitalet and Faculty of Medicine, University of Oslo, Norway.