Ferumoxytol-Enhanced MRI in Children and Young Adults: State of the Art.

Ferumoxytol is an ultrasmall iron oxide nanoparticle, originally approved in 2009 by the FDA for IV treatment of iron deficiency in adults with chronic kidney disease. Subsequently, its off-label use as an MRI contrast agent has increased in clinical practice, particularly in pediatric patients in North America. Unlike conventional MRI contrast agents that are based on the rare earth metal gadolinium [gadolinium-based contrast agents (GBCAs)], ferumoxytol is biodegradable and carries no potential risk of nephrogenic systemic fibrosis. At FDA-approved doses, ferumoxytol demonstrates no long-term tissue retention in patients with intact iron metabolism. Ferumoxytol provides unique MRI properties including long-lasting vascular retention (facilitating high-quality vascular imaging) and retention in reticuloendothelial system tissues, thereby supporting a variety of applications beyond those possible with GBCAs. This Clinical Perspective describes clinical and early translational applications of ferumoxytol-enhanced MRI in children and young adults through off-label use for a variety of settings, including vascular, cardiac, and cancer imaging, drawing on the authors' institutional experience. In addition, we describe current preclinical and clinical research advances using ferumoxytol with regard to cellular and molecular imaging, and also as a novel potential cancer therapeutic agent.