1. Department of Radiology, Perelman School of Medicine, University of Pennsylvania, 1012, 231 S. 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
2. Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
3. Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6303, United States
4. Department of Neurology, Washington University School of Medicine, Saint Louis, Missouri 63110-1010, United States
5. Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
6. Center for Neurodegenerative Disease Research, Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-2676, United States