1Section on Experimental Radiology, Department of Diagnostic and Interventional Radiology, IDM of the Helmholtz Center Munich at the University Tübingen, German Center for Diabetes Research (DZD), Tuebingen, Germany, 2Section on Experimental Radiology, Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tuebingen, Germany, 3Department of Endocrinology and Diabetology, Angiology, Nephrology and Clinical Chemistry, IDM of the Helmholtz Center Munich at the University Tübingen, German Center for Diabetes Research (DZD), Tuebingen, Germany, 4Department of Diagnostic and Interventional Radiology, University Hospital Tuebingen, Tuebingen, Germany