1. Department of Radiology, The University of Tokyo, Tokyo, Japan
2. Choju Medical Institute, Fukushimura Hospital, Toyohashi, Aichi, Japan
3. Department of Radiology, National Center for Geriatrics and Gerontology, Obu, Aichi, Japan
4. Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan