Ultrasound and MRI Measurements of Joint Cartilage in Healthy Children: a Validation Study - Spannow, A. H.; Stenboeg, E.; Pfeiffer-Jensen, M.; Fiirgaard, B.; Haislund, M.; Ostergaard, M.; Andersen, N. T.; Herlin, T. (Ultraschall in der Medizin - European Journal of Ultrasound, 2011)