Dual Energy CT Imaging of Atherosclerotic Plaque using Novel Ultrasmall Superparamagnetic Iron Oxide in Hyperlipidemic Rabbits

Abstract Purpose The purpose of this study was to examine whether the use of dual energy CT (DECT) facilitated the visualization of carboxymethyl-diethylaminoethyl dextran magnetite ultra-small superparamagnetic iron oxide (CMEADM-U) accumulation in arteriosclerotic lesions using hyperlipidemic rabbits. Methods CMEADM-U at 0.5 mmol Fe/kg was administered to Watanabe hereditary atherosclerotic (WHHL) rabbits (n = 6, 24 sections) and New Zealand white (NZW) rabbits (n = 2, 6 sections). After 72 hours, DECT was performed to prepare virtual monochromatic images (VMI: 35keV, 70keV) and an iron-based map. Subsequently, the aorta was collected, and hematoxylin & eosin staining, berlin blue staining, and RAM11 immunostaining. Results DECT images were prepared to evaluate the association with CMEADM-U accumulation. In the WHHL rabbits, CMEADM-U accumulation was not observed at 70 keV. However, CMEADM-U accumulation consistent with an arteriosclerotic lesion was observed at 35 keV and the iron-based map. On the other hand, in the NZW rabbits, there was no CMEADM-U accumulation in any images. Further, there were significant differences in the iron-based map value at the site of accumulation among the grades of expression on berlin blue staining and RAM11 immunostaining. In addition, there was a good correlation at 35kev and iron-based map value (r = 0.42, p < 0.05). Conclusion DECT imaging for CMEADM-U facilitated the assessment of macrophage accumulation in atherosclerotic lesions in an in vivo study using a rabbit model of induced aortic atherosclerosis.