1. Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Biostatistics Collaboration Unit, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Department of Surgery, Pusan National University School of Medicine and Medical Research Institute, Busan, Korea.
5. Department of Surgery, Ulsan University Hospital, Ulsan, Korea.