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Nanotheranostics 2020; 4(4):195-200. doi:10.7150/ntno.46356 This issue Cite

Research Paper

Brain iron deposition after Ferumoxytol-enhanced MRI: A study of Porcine Brains

Ashok Joseph Theruvath^1,2, Maryam Aghighi¹, Michael Iv¹, Hossein Nejadnik¹, Jonathan Lavezo³, Laura Jean Pisani¹, Heike Elisabeth Daldrup-Link^1✉

1. Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, CA, USA.
2. Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, 55131 Mainz, Germany.
3. Department of Pathology, School of Medicine, Stanford University, Stanford, CA, USA.

✉ Corresponding author: Heike E. Daldrup-Link, Molecular Imaging Program at Stanford, Stanford University, 725 Welch Road, Stanford, CA 94304, E-mail: heikededu.

Abstract

Recent evidence of gadolinium deposition in the brain has raised safety concerns. Iron oxide nanoparticles are re-emerging as promising alternative MR contrast agents, because the iron core can be metabolized. However, long-term follow up studies of the brain after intravenous iron oxide administration have not been reported thus far. In this study, we investigated, if intravenously administered ferumoxytol nanoparticles are deposited in porcine brains.

Methods: In an animal care and use committee-approved prospective case-control study, ten Göttingen minipigs received either intravenous ferumoxytol injections at a dose of 5 mg Fe/kg (n=4) or remained untreated (n=6). Nine to twelve months later, pigs were sacrificed and the brains of all pigs underwent ex vivo MRI at 7T with T2 and T2*-weighted sequences. MRI scans were evaluated by measuring R2* values (R2*=1000/T2*) of the bilateral caudate nucleus, lentiform nucleus, thalamus, dentate nucleus, and choroid plexus. Pig brains were sectioned and stained with Prussian blue and evaluated for iron deposition using a semiquantitative scoring system. Data of ferumoxytol exposed and unexposed groups were compared with an unpaired t-test and a Mann-Whitney U test.

Results: T2 and T2* signal of the different brain regions was not visually different between ferumoxytol exposed and unexposed controls. There were no significant differences in R2* values of the different brain regions in the ferumoxytol exposed group compared to controls (p>0.05). Prussian blue stains of the same brain regions, scored according to a semiquantitative score, were not significantly different either between the ferumoxytol exposed group and unexposed controls (p>0.05).

Conclusions: Our study shows that intravenous ferumoxytol doses of 5-10 mg Fe/kg do not lead to iron deposition in the brain of pigs. We suggest iron oxide nanoparticles as a promising alternative for gadolinium-enhanced MRI.

Keywords: iron oxide nanoparticle, brain deposition, MRI

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