1. From the Department of Radiology (B.M.K., D.I.K., D.J.K., S.I.P.), Yonsei University College of Medicine, Severance Hospital; Neurosurgery Department (Y.S.S.), Catholic University of Korea, St. Mary's Hospital; Neurosurgery Department, Ajou University College of Medicine (S.-H.K.); Radiology Department (S.H.S.), Yonsei University College of Medicine, Gangnam Severance Hospital; and the Radiology Department (Y.-K.I.), Catholic University of Korea, St. Vincent's Hospital, Suwon, Korea.