1. Molecular
Imaging Program at Stanford, Department of Radiology, Stanford University School of Medicine, 1201 Welch Road, Stanford, California 94305-5484, United States
2. Department
of Radiology, Neuroimaging and Neurointervention Division, Stanford University Hospital, 300 Pasteur Drive, Stanford, California 94305, United States
3. Institute
of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory
for Carbon-based Functional Materials and Devices, Soochow University, Suzhou, Jiangsu 215123, China