1. Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, New York 11794, USA
2. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
3. Department of Materials Science and Engineering, National University of Singapore, Singapore 117575
4. QuantumWise A/S, Fruebjergvej 3, Postbox 4, DK-2100 Copenhagen, Denmark