SPIO

From NMR Wiki

Superparagmagnetic Iron Oxide Compounds.

A small iron crystallite is surrounded by a chelating material. The magnetic moment of the crystallite is composed additively from the moments of the single iron ions. The highly paramagnetic behaviour offers an opportunity for cell labeling and diffusion tracking experiments, e.g. with macrophages carrying the SPIO molecules.

SPIO molecules have a diameter of 10 nm ("ultrasmall SPIO", USPIO) up to several millimeters ("medium sized iron oxides", MION) and are used for T2 imaging agents in vascular and gastroenteral imaging.