Published: 13 November 2017
This work is funded by National Health and Medical Research Council (HTT: APP1037310), University of Queensland Early Career Grant (HTT: UQECR1606713), the Australian Research Council (AKW: CE140100036), and the National Natural Science Foundation of China (ZL: 81471657). The authors would like to acknowledge the Australian National Fabrication Facility (Queensland Node); National Imaging Facility, Centre for Advanced Imaging for access to key items of equipment. The authors also acknowledge the facilities, and the scientific and technical assistance of the Australian Microscopy and Microanalysis Research Facility at the Centre for Microscopy and Microanalysis, the University of Queensland.
This study aims to compare the relaxivities of ultra-small dual positive and negative contrast iron oxide nanoparticles (DCION) at different magnetic field strengths ranging from 4.7 to 16.4 T at physiological temperatures; and to investigate the effect of particle aggregation on relaxivities. Relaxivities of DCIONs were determined by magnetic resonance imaging scanners at 4.7, 7, 9.4, and 16.4 T. Both longitudinal (T 1) and transverse relaxation times (T 2) were measured by appropriate spin-echo sequences. It has been found that both longitudinal and transverse relaxivities are significantly dependent on the magnetic field strength. Particle aggregation also strongly affects the relaxivities. Awareness of the field strength and particle colloid stability is crucial for the comparison and evaluation of relaxivity values of these ultra-small iron oxide nanoparticles, and also for their medical applications as contrast agents.
Hang T T, Zhen Li, Yuao Wu, Gary Cowin, Shaohua Zhang, Anya Yago, Andrew K Whittaker and Zhi Ping Xu
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