Vascular and plaque imaging with ultrasmall superparamagnetic particles of iron oxide

Table 1 Iron oxide nanoparticle preparations

Particle	Size (Diameter)	Plasma half-life (h)	Application
Microparticles of iron oxide (MPIOs)	1–6 μm [53]	1–2 min	Readily endocytosed and detected with CMR [53]. Need immediate scan following infusion.
			Can be combined with ligands for cellular targets allowing molecular imaging [54].
			Large size means they remain in the blood pool and are suitable for endovascular imaging t [55].
Superparamagnetic particles of iron oxide (SPIOs)	65–150 nm [56]	2–3 h	Ferumoxide (Endorem, Guerbet, France) and ferucarbotran (Resovist, Bayer-Schering Pharma, Germany).
			Recognised by cells of the reticuloendothelial system. Have been used for oncological imaging including liver studies where they are taken up by Kuppfer cells in normal tumour-free liver [57].
			Mesenchymal stem cell, monocyte/macrophage labelling [58].
Ultrasmall SPIO (USPIOs)	<50 nm [59]	Ferumoxytol: 9–15 h	Ferumoxtran-10 (Sinerem, Guerbet, France) and ferumoxytol (Rienso, Takeda, United Kingdom).
Ultrasmall SPIO (USPIOs)	<50 nm [59]	Ferumoxtran-10: 25–30 h
Very small superparamagnetic iron oxide particles (VSOPs)	<10 nm [60]	1 h	Alternative blood pool agents with longer circulating half-life than gadolinium based agents [61, 62].
Very small superparamagnetic iron oxide particles (VSOPs)	<10 nm [60]	1 h	Potential as cell tracking agents [63].

ISSN: 1532-429X