1. Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 143-792, Korea.
2. Department of Neurology, Hanyang University Medical Center, Hanyang University School of Medicine, Seoul 133-791, Korea.
3. Department of Neurology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul 143-792, Korea.
4. Center for Geriatric Neuroscience Research, Konkuk University School of Medicine, Seoul 143-792, Korea.