1. Department of Radiology, Seoul National University Hospital, Jongno-gu, Seoul 03080, Korea
2. Department of Biomedical Sciences, Seoul National University College of Medicine, Jongno-gu, Seoul 110-799, Korea
3. Department of Radiology, Yanbian University Hospital, JiLin Province 133000, China
4. Department of Pathology and Cancer Research Center, Yanbian University Medical College, Yanji 133002, China