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Abstract
Atherosclerosis is characterized by progressive accumulation of lipids and inflammatory cells within the artery wall. It is a diffuse systemic disease; however, some atherosclerotic plaques are more prone to rupture causing sudden thromboembolic vascular occlusions, while others are clinically silent. Therefore, to prevent such devastating vascular events as stroke or myocardial infarction, clinicians need to have smart tools to localize high-risk vulnerable plaques, which have been a huge challenge to date. Molecular imaging, which visualizes biologic processes at the cellular and molecular level, has a potential to assess plaque vulnerability and consequently identify high-risk patients prior to the development of the clinical events. In this review, we summarize important updates on the molecular imaging of atherosclerosis in the field of optical imaging, magnetic resonance imaging, positron emission tomography, and computerized tomography imaging.
Figures and Tables
Figure 1
Duplex ultrasonography (A) and angiography (B) imaging to provide structural information about carotid atherosclerosis. (A) On the carotid sonography, the atherosclerotic plaque is shown to have heterogeneous echodensity(blue arrows). (B) The angiography shows significant atherosclerotic narrowing of the internal carotid artery. Current atherosclerosis practice heavily relies on these anatomy-based structural imaging modalities.
Figure 2
Cathepsin-B molecular optical imaging to reflect pro-atherosclerotic and anti-atherosclerotic effects by high cholesterol diet and atorvastatin treatment, respectively. Eight-week-old ApoE knock-out mice were on a normal chow diet, western diet, or western diet with atorvastatin for 14 weeks. The Cathepsin-B images of the representative animals' aortas show that Cathepsin-B activity signal is stronger in the mouse on a high cholesterol diet than in the mouse on a normal diet. In the animal on a western diet + atorvastatin, the Cathepsin-B activity signal is as low as in the animal on a normal diet. Please note that similarly-looking plaques on the color photograph (of the animal on a western diet) have different signal intensities on the CatB image (arrows and arrow heads). Adapted from Kim et al (24) with permission from the Korean Neurological Association.
Figure 3
MR Images before (A) and after (B) the intravenous injection of CLIO (cross-linked iron oxide) nanoparticles into the 9-month-old ApoE k/o mouse with atherosclerotic aorta. Compared with the baseline image (A), post-contrast image (B) reveals dark signal from macrophages that phagocitized the nanoparticles and migrated to the root of the atherosclerotic aorta. (Figure courtesy of Dr. Matthias Nahrendorf, Harvard Medical School).
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