1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland, 2Medical Research Center, University of Oulu and Oulu University Hospital, Oulu, Finland, 3Department of Applied Physics, University of Eastern Finland, Kuopio, Finland, 4Center for Magnetic Resonance Research, Minneapolis, MN, United States, 5Department of Radiology, University of Minnesota, Minneapolis, MN, United States, 6Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland, 7Department of Applied Physics, University of Eastern Finland, Oulu, Finland