1. The Russell H. Morgan Department of Radiology & Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland
2. Department of Neurology, CentraCare Clinic, St Cloud, Minnesota
3. Departments of Epidemiology and Medicine and Welch Center for Prevention, Epidemiology, and Clinical Research, The Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
4. Department of Neurology, The Johns Hopkins Hospital, Baltimore, Maryland
5. Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia