1. Department of Surgery; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea
2. Department of Radiology; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea
3. Department of Internal Medicine; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea
4. Departments of Clinical Epidemiology and Biostatistics; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea