1. Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
2. Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736, Korea.
3. Department of Imaging, Dana-Farber Cancer Institute, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.