1. The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
2. Department of Orthopedic Surgery, The Johns Hopkins University, Baltimore, MD 21287, USA
3. Center for Osteonecrosis Research and Education, Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
4. Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT 84132, USA
5. Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA