VSION as high field MRI T₁ contrast agent: evidence of their potential as positive contrast agent for magnetic resonance angiography

Abstract

Because of their outstanding magnetic properties, iron oxide nanoparticles have already been the subject of numerous studies in the biomedical field, in particular as a negative contrast agent for T-weighted nuclear magnetic resonance imaging, or as therapeutic agents in hyperthermia experiments. Recent studies have shown that below a given particle size (i.e. 5 nm), iron oxide may be used to provide a significant positive (brightening) effect on T-weighted MRI. In such an application, not only the size of the crystal, but also the control of the coating process is essential to ensure optimal properties, especially at a very high field (> 3 T). In this work, we focused on the development of very small iron oxide nanoparticles as a potential platform for high field T magnetic resonance angiography (MRA) applications. The feasibility has been evaluated in vivo at 9.4 T, demonstrating the usefulness of the developed system for MRA applications.

Iron Oxide Nanoparticles: An Alternative for Positive Contrast in Magnetic Resonance Imaging

“…Results showed that IONPs with a thinner coating yielded an excellent positive T 1 -MRI contrast, more specifically NPs synthesised at 120 • C. These NPs, with a hydrodynamic size of 7.9 nm and a r 2 /r 1 ratio of 1.9 showed great contrast enhancement in both body and brain MRA of healthy mice, providing the possibility of better visualising their vasculature. In 2018, Vangijzegem et al [98] synthesised very small PEGylated iron oxide nanoparticles (VSIONPs) with core sizes of 3.5 nm that showed positive contrast in in vivo MRA, enabling the heart chamber and the vena cava of healthy mice to be observed.…”

Influence of Experimental Parameters of a Continuous Flow Process on the Properties of Very Small Iron Oxide Nanoparticles (VSION) Designed for T1-Weighted Magnetic Resonance Imaging (MRI)

“…Both procedures allow the formation of nearly monodisperse iron oxide nanoparticles, with tunable sizes, by simply varying the experimental parameters based on the precise separation between the nucleation and the growth steps involved in the formation mechanism of the nanocrystals [35]. For the preparation of VSION, we decided to apply a previously established process [20] which consisted in the direct injection of a solution containing the iron organometallic complex solubilized in oleylalcohol in a solution of hydrophobic surfactants (e.g., oleic acid, oleylamine and 1,2-hexadecanediol in a 1:1:5 molar ratio) in a dibenzylether solution preheated at 300 • C. As a result, VSION with well-defined properties were readily obtained. Figure 1A presents a TEM image of the resulting nanoparticles which show spherical morphology and exhibiting an average diameter of 3.5 ± 0.6 nm (PDI: 1.1).…”

“…Nanomaterials 2020, 10, x FOR PEER REVIEW 5 of 18 growth steps involved in the formation mechanism of the nanocrystals [35]. For the preparation of VSION, we decided to apply a previously established process [20] which consisted in the direct injection of a solution containing the iron organometallic complex solubilized in oleylalcohol in a solution of hydrophobic surfactants (e.g., oleic acid, oleylamine and 1,2-hexadecanediol in a 1:1:5 molar ratio) in a dibenzylether solution preheated at 300 °C. As a result, VSION with well-defined properties were readily obtained.…”

“…For these reasons, the development of nanoparticulate T 1 contrast agents, based on iron oxide nanoparticles, has become a forward-looking area of research for MRI. On the contrary to the classical clinically used T 2 contrast agents (Endorem), very small (<5 nm) iron oxide nanoparticles (VSION) are potential candidates for T 1 -weighted imaging, due to their low magnetization and the presence of a surface spin-canted layer [18][19][20]. However, one must stress that control over the size and size distribution is an essential prerequisite to observe VSION-induced contrast enhancement on T 1 -weighted images.…”

Atherosclerosis Treatment with Stimuli‐Responsive Nanoagents: Recent Advances and Future Perspectives

“…Second, MPO(Gd) is sensitive to myeloperoxidase enzymes that is beneficial for detection of vulnerable plaques. However, due to the increased possibility of nephrotoxicity of gadolinium‐based contrast agents, ION‐based positive contrast agents have become a research hotspot today …”