Dual-energy CT imaging of atherosclerotic plaque using novel ultrasmall superparamagnetic iron oxide in
Hideyuki Sato1,2, Shinichiro Fujimoto1, Yuko O Kawaguchi1
1Department of Cardiovascular Biology and Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan.
Background:
A study using magnetic resonance imaging (MRI) revealed that ultra-small superparamagnetic iron oxide is phagocytosed by macrophages. However, MRI has limitations in obtaining clear images due to its poor spatial and temporal resolutions.
Purpose:
To examine whether the use of dual-energy computed tomography (DECT) facilitated the visualization of carboxymethyl-diethylaminoethyl dextran magnetite ultra-small superparamagnetic iron oxide (CMEADM-U) accumulation in arteriosclerotic lesions using hyperlipidemic rabbits.
Material And 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 h, DECT was performed to prepare virtual monochromatic images (35 keV, 70 keV) and an iron-based map. Subsequently, the aorta was collected along with hematoxylin and eosin staining, Berlin blue (BB) staining, and RAM11 immunostaining.
Results:
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 accumulation of CMEADM-U 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 BB staining and RAM11 immunostaining. In addition, there was a good correlation at 35 kev 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.
Insights
Dual-energy computed tomography (DECT) effectively visualizes carboxymethyl-diethylaminoethyl dextran magnetite ultra-small superparamagnetic iron oxide (CMEADM-U) accumulation in arteriosclerotic lesions, aiding macrophage assessment in rabbits.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Cardiovascular Research
Background:
- Magnetic resonance imaging (MRI) shows ultra-small superparamagnetic iron oxide (USPIO) uptake by macrophages.
- MRI has limitations in spatial and temporal resolution for imaging USPIO accumulation.
Purpose of the Study:
- To evaluate dual-energy computed tomography (DECT) for visualizing carboxymethyl-diethylaminoethyl dextran magnetite ultra-small superparamagnetic iron oxide (CMEADM-U) in arteriosclerotic lesions.
- To assess CMEADM-U accumulation in hyperlipidemic rabbit models of atherosclerosis.
Main Methods:
- CMEADM-U was administered to Watanabe hereditary atherosclerotic (WHHL) and New Zealand white (NZW) rabbits.
- DECT imaging was performed, generating virtual monochromatic images (35 keV, 70 keV) and an iron-based map.
- Aorta analysis included hematoxylin and eosin, Berlin blue, and RAM11 immunostaining.
Main Results:
- CMEADM-U accumulation was visualized at 35 keV and on the iron-based map in WHHL rabbits, correlating with arteriosclerotic lesions.
- No CMEADM-U accumulation was detected in NZW rabbits.
- Iron-based map values showed significant differences based on macrophage marker expression and correlated with 35 keV imaging.
Conclusions:
- DECT imaging effectively visualizes CMEADM-U accumulation in atherosclerotic lesions.
- DECT facilitates assessment of macrophage accumulation in an in vivo rabbit atherosclerosis model.
- This technique offers improved imaging of nanoparticle-based contrast agents in atherosclerosis research.
