1. Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
2. Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
3. Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland
4. Department of Physical and Rehabilitation Medicine, Helsinki University Hospital, Helsinki, Finland
5. Griffith Centre of Biomedical and Rehabilitation Engineering (GCORE), Menzies Health Institute, Queensland and Advanced Design and Prototyping Technologies Institute (ADAPT), and the School of Health Sciences and Social Work, Griffith University, Gold Coast, QLD, Australia