Corresponding author.; Multi-Modality Medical Imaging, Technical Medical Centre, University of Twente, P.O. Box 217, 7500 AE, Enschede, the Netherlands
S.S. Gambhir
Department of Radiology, Molecular Imaging Program at Stanford (MIPS), The Bio-X Program, Stanford, CA 94305, USA; Department of Bioengineering, Department of Materials Science & Engineering, Stanford University, Stanford, CA 94305, USA