1CIBM-LIFMET, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 2Forschungszentrum Jülich, Jülich, Germany, 3CIBM-AIT, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 4LIFMET, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 5Department of Radiology, University of Geneva, Geneva, Switzerland, 6Department of Radiology, University of Lausanne, Lausanne, Switzerland