1. Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
2. Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
3. Sectra AB, Linköping, Sweden
4. Department of Medicine and Health Sciences, Section of Radiological Sciences. Faculty of Health Sciences, Linköping, Sweden
5. Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden