1. Department of Nuclear Medicine, RWTH Aachen University, 52074 Aachen, Germany
2. DWI − Leibniz-Institute for Interactive Materials, RWTH Aachen University, 52074 Aachen, Germany
3. Max Planck Institute for Medical Research, Heidelberg 69120, Germany
4. Department of Nuclear Medicine, Maastricht University Medical Centre, 6229 HX Maastricht, Netherlands