1. Department of Radiology, Karolinska Hospital, Stockholm S-171 76, Sweden
2. Department of Pathology and Cytology, Karolinska Hospital, Stockholm S-171 76, Sweden
3. Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
4. Instituto Orthopedico Rizzoli, Anatomia Patologica, Bologna 40136, Italy
5. Department of Orthopaedics, Karolinska Hospital, Stockholm S-171 76, Sweden