Abstract 590: Atherosclerotic Plaque Characterization Using Iodinated Nanoparticles Contrast and Gadolinium in Two Layers Dual Energy MDCT
Purpose: To demonstrate the feasibility of Dual Energy MDCT to characterize rabbit’s atherosclerotic plaque components with iodine based nanoparticulate contrast agent (NPC) and gadolinium.
Materials and Methods: Advanced atherosclerotic plaques were induced in 12 NZW rabbits using high cholesterol diet and repeated aortic endothelial denudation. Four non-atherosclerotic rabbits served as negative controls. Rabbits were scanned in Dual Energy MDCT (Brilliance, Philips Healthcare, Cleveland, OH) after 6 months. N1177 NPC (NanoScan Imaging, Landsdale, PA) was injected to the marginal ear vein. Dual energy scans were performed precontrast, immediately after injection and 2 hours after the injection. In addition, another scan was performed 3 hours after NPC injection, during IV injection of gadolinium. Aortic lumen narrowing and late vessel wall NPC accumulation were analyzed. Spectral analysis was performed on late scans with and without gadolinium. The rabbits were sacrificed after the scan and the aorta was microscopically evaluated for atherosclerosis and macrophage content.
Results: CT angiography of the atherosclerotic rabbits demonstrated irregular vessel wall with non-calcified plaques and mild (up to 25%) narrowing. Normal aortas were demonstrated in the control rabbits. Late scanning demonstrated localized NPC accumulation in atherosclerotic lesions with improved visualization using spectral analysis in comparison to regular CT images. No delayed enhancement of the vessel wall was demonstrated in control animals. Late gadolinium injection resulted in luminal density of 134 +/−24 HU, similar to vessel wall enhancement of NPC. Spectral analysis successfully differentiated between intra-luminal gadolinium and vessel wall accumulation of NPC. Microscopic evaluation of atherosclerotic plaques demonstrated correlation between plaque’s macrophages content and aortic NPC accumulation.
Conclusion: NPC accumulated in atherosclerotic plaques identified macrophages’ rich lesions. Spectral analysis of double contrast Dual Energy scan successfully differentiated between intra-luminal gadolinium and extra-luminal iodine stained macrophages.