1. Department of Radiology and Center for Imaging Science, Samsung Medical Center; Sungkyunkwan University School of Medicine; 81 Irwon-ro, Gangnam-gu Seoul 135-710 Korea
2. Department of Radiology, CHA Bundang Medical Center; CHA University; 351 Yatap-dong, Bundang-gu, Seongnam Gyeonggi-do 463-712 Korea