1. Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Korea.
2. Department of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Institute of Radiation Medicine, Seoul National University Medical Research Center, Clinical Research Institute, Seoul National University Hospital, Gyeonggi-do 463-707, Korea.
3. Department of Urology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Gyeonggi-do 463-707, Korea.
4. Department of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 110-744, Korea.