1. Department of Radiology, Center for Evidence-Based Imaging, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115.
2. Department of Radiology, Stanford Health Care, Stanford School of Medicine, Stanford, CA.
3. Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
4. Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.