1. Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
2. Present address: Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada.
3. Department of Imaging, Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA 02215.
4. Juravinski Hospital and Cancer Centre, McMaster University, Hamilton, ON, Canada.
5. Department of Oncology, Dana-Farber Cancer Institute, Boston, MA.