1. Department of Radiology, St Vincent's University Hospital, Elm Park, Dublin, Ireland.
2. Department of Imaging, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA.
3. Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115.
4. Department of Radiology, UH Cleveland Medical Center, Case Western Reserve University, Cleveland, OH.