Shohei Fujita1, Akifumi Hagiwara2, Shigeki Aoki2, Osamu Abe3. 1. Department of Radiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan; Department of Radiology, Juntendo University Hospital, Tokyo, Japan. Electronic address: shifujita-tky@umin.ac.jp. 2. Department of Radiology, Juntendo University Hospital, Tokyo, Japan. 3. Department of Radiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.