1. Department of Nuclear Medicine; RWTH Aachen University; Aachen 52074 Germany
2. DWI - Leibniz Institute for Interactive Materials; RWTH Aachen University; Aachen 52074 Germany
3. Department of Radiology and Nuclear Medicine; Maastricht University Medical Center; Maastricht 6229 HX The Netherlands
4. Pathology-Electron Microscopy Facility; RWTH Aachen University; Aachen 52074 Germany