1. From the Department of Radiology, Catholic Kwandong University College of Medicine, Catholic Kwandong University International St. Mary’s Hospital, Incheon, Korea (R.G.Y.); Department of Radiology, Jeju National University Hospital, Jeju, Korea (M.J.G.); Department of Radiology and Research Institute of Radiology (H.S.K., W.H.S., S.C.J., S.J.K.) and Department of Neurosurgery (J.H.K.), University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-Gil, Songpa-Gu, Seoul 138-736, Korea.