Amsterdam University Medical Centers, location AMC, Department of Radiology and Nuclear Medicine, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands; Amsterdam Movement Sciences Research Institute, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands; Amsterdam University Medical Centers, location AMC, Department of Pediatric Rheumatology, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands; Department of Radiology, University College London Hospital, 235 Euston Rd, NW12BU, London, United Kingdom. Electronic address: a.m.barendregt@amsterdamumc.nl.