1. Department of Radiology; Seoul National University Hospital; 101 Daehak-ro, Jongno-gu Seoul 110-744 South Korea
2. Department of Radiology; Yanbian University Hospital; 1327 JuZi Street Yanji City JiLin Province 133000 China
3. Korea Advanced Institute of Science and Technology (KAIST); 291 Daehak-ro, Yuseong-gu Daejeon 305-701 South Korea