1. Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
2. Diagnostic Imaging Centre, Kuopio University Hospital, Kuopio, Finland
3. Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
4. Medical Research Center Oulu, University of Oulu, Oulu, Finland
5. Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland