1. Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg 405 30, Sweden
2. Department of Radiology, Sahlgrenska University Hospital, Gothenburg 413 45, Sweden
3. Departments of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo 0372, Norway
4. Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg 405 30, Sweden
5. Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg 413 45, Sweden
6. CF-Centre, Sahlgrenska University Hospital, Gothenburg 413 45, Sweden
7. Department of Respiratory Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden