1. From the Molecular Imaging Laboratory, Department of Radiology, and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA; Joseph Stokes Jr. Research Institute, The Children's Hospital of Philadelphia, Philadelphia, PA; Department of Materials Science and Engineering and Department of Biochemistry and Biophysics, Johnson Research Foundation, University of Pennsylvania, Philadelphia, PA; and Division of Biophysics and Bioimaging, Ontario...