The magnetic resonance characteristics of SPIONs for imaging at ultralow field (6.5 mT)

Characterization of the parameters of superparamagnetic iron oxide nanoparticles (SPIONs) can guide synthesis of optimized particles for use in magnetic resonance imaging (MRI). With a goal of application of SPIONs in ultra-low field (ULF) MRI, we investigated the properties of SPIONs, and conducted imaging on a 6.5 mT MRI scanner. Specifically, we measured the NMR relaxivity and susceptibility of different SPIONs sample, both dominated by the core size of SPIONs. We also implemented susceptibility imaging using an bSSFP sequence to obtain positive contrast images of SPION phantoms, and present here a method to optimize the ULF susceptibility MRI images.