ABSTRACT
Superparamagnetic iron oxides (IOs) have been widely used as a diagnostic
agent for magnetic resonance imaging (MRI) because of their favorable magnetic
properties and acceptable biocompatibility. The synthetic magnetite (Fe3O4) and
magnemite (γ -Fe2O3) have the highest saturation magnetization (Ms) among all
other IOs and no remnant magnetic moment once the external magnetic field is
withdrawn [1]. Superparamagnetic IOs increase R2 and R2* relaxation rates of the surrounding medium to create signals void on MR images. The effects of the
superparamagnetic IOs as a contrast agent for MRI depend upon their magnetic
susceptibility to achieve magnetic enhancement [2]; their size, which ideally
should be in the range of 6-15 nm [3]; their superparamagnetic characteristics
[4]; and their surface chemistry for specific biomedical applications [5].
