1. Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University , 1-1-1 Honjo, 860-8556 Kumamoto , Japan
2. Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
3. Department of Neurology, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan
4. Center of Metabolic Regulation of Healthy Aging, Faculty of Life Sciences, Kumamoto University , Kumamoto , Japan