Matrix-dependent T2 relaxivity of iron oxide (Fe3O4) nanoparticle-doped agarose gel phantoms for magnetic resonance imaging at 1.5 T

Abstract

Phantoms are tissue-mimicking tools used in the development and performance verification of medical imaging systems. Agarose gel is an alternative phantom material that has the ability to emulate biological tissues, often used in evaluating the relaxivity of novel contrast agents for MRI. However, the addition of hydrophilic contrast agents such as citrate-stabilized iron oxide nanoparticles (IONPs@Citrate) could alter the microstructure of the gel and result in matrix-dependent relaxivity values. In this paper, IONPs@Citrate are suspended in different concentrations of agarose gel and the relaxivity of the phantoms were measured using a 1.5 T MRI scanner. Results show that increasing the agarose gel concentration from 1.5% to 2.0% results in a signifcant decline (p < 0.001) in relaxivity values presumably attributed to the intermolecular interactions of the gel and the nanoparticles. Ultimately, these findings highlight the importance of phantom matrix microstructure in standardizing pre-clinical evaluation of MRI contrast agents.