1. Department of Radiology, University Hospital of North Norway, Tromsø, Norway
2. Department of Neurosurgery, Faculty of Medicine, University of Tromsø, Tromsø, Norway
3. Department of Neurosurgery, Oslo University Hospital/Rikshospitalet, Oslo, Norway
4. Department of Neurosurgery, University Hospital of North Norway, Tromsø, Norway
5. Department of Radiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway