For example, while 500–1,000 μmol Fe/kg body weight was needed for magnetic resonance imaging (MRI) of atherosclerosis plaques in ApoE knockout mouse through non-targeted iron oxide nanoparticles (Klug et al., 2009), the amounts of agents needed could be reduced to 36 μmol Fe/kg when iron oxide nanoprobes were decorated with anti-CD163 mAb for active targeting of macrophages residing in inflammatory atherosclerotic plaques (Figure 2A) (Tarin et al., 2015). Here, APOE is linked to atherosclerosis.