1. Department of Radiology, Ajou University School of Medicine , Wonchon-Dong, Yeongtong-Gu, Suwon 16499 , South Korea
2. Department of Radiology, GangNeung Asan Hospital, University of Ulsan College of Medicine , Gangneung-si, Gangwon-do 25440 , South Korea
3. Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine , Seoul 03080 , South Korea