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Iron Oxide Nanoparticles as Positive T1 Contrast Agents for Low-Field Magnetic Resonance Imaging at 64 mT



Samuel Oberdick, Kalina Jordanova, John Lundstrom, Giacomo Parigi, Megan Poorman, Gary Zabow, Katy Keenan


We have investigated the efficacy of superparamagnetic iron oxide nanoparticles (SPIONs) as positive T1 contrast agents for low-field magnetic resonance imaging (MRI) at 64 millitesla (mT). Iron-oxide based agents, such as the FDA-approved ferumoxytol, were measured using a variety of techniques to evaluate T1 contrast at 64 mT. Additionally, we characterized monodispersed carboxylic acid coated SPIONs with a range of sizes (4.9 nm to 15.7 nm) in order to understand size-dependent properties of T1 contrast at low-field. MRI contrast properties were measured using 64 mT MRI, magnetometry and nuclear magnetic resonance dispersion (NMRD) curves. We also measured MRI contrast at 3 T to provide comparison to a standard clinical field strength. We find that SPIONs have the capacity to perform well as T1 contrast agents at 64 mT. We measure longitudinal relaxation (r1) values of up to 67 L mmol-1 s-1, which is more than an order of magnitude higher than corresponding r1 values at 3 T. The particles have longitudinal relaxivities that are size-dependent and outperform a commercial Gd-based agent (gadobenate dimeglumine) by up to 8.3x at physiological temperatures. Additionally, we characterize the ratio of transverse to longitudinal relaxivity, r2/r1 and find that it is 1 for the SPION based agents at 64 mT, indicating a favorable balance of relaxivities for T1-weighted contrast imaging. We also correlate the magnetic and structural properties of the particles with models of nanoparticle relaxivity to understand generation of T1 contrast. These experiments suggest that SPIONS have desirable magnetic properties for future, exciting applications as T1 agents at low fields.
Nature - Scientific Reports


Magnetic Resonance Imaging (MRI), Magnetic Nanoparticles


Oberdick, S. , Jordanova, K. , Lundstrom, J. , Parigi, G. , Poorman, M. , Zabow, G. and Keenan, K. (2023), Iron Oxide Nanoparticles as Positive T1 Contrast Agents for Low-Field Magnetic Resonance Imaging at 64 mT, Nature - Scientific Reports, [online], (Accessed June 13, 2024)


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Created July 17, 2023, Updated October 9, 2023