Hye Sun Park1, Jung Hwan Baek1, Dong Gyu Na2,3. 1. a Department of Radiology and Research Institute of Radiology , University of Ulsan College of Medicine, Asan Medical Center , Seoul , Republic of Korea. 2. b Department of Radiology , GangNeung Asan Hospital , Gangneung-si Gangwon-do , Republic of Korea. 3. c Department of Radiology , Human Medical Imaging and Intervention Center , Seocho-gu Seoul , Republic of Korea.