1. Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8601 Japan.
2. Department of Radiology, Saishūkan Hospital, Kitanagoya-shi, Japan.
3. Department of Radiology, Nagoya City West Medical Center, Nagoya, Japan.
4. Department of Radiology, Kasugai Municipal Hospital, Kasugai-shi, Japan.