Dual-Energy Computed Tomography Imaging of Atherosclerotic Plaques in a Mouse Model Using a Liposomal-Iodine Nanoparticle Contrast Agent
Background-The accumulation of macrophages in inflamed atherosclerotic plaques has been long recognized. In an attempt to develop an imaging agent for detection of vulnerable plaques, we evaluated the feasibility of a liposomal-iodine nanoparticle contrast agent for computed tomography (CT) imaging of macrophage-rich atherosclerotic plaques in a mouse model.
Methods and Results-Liposomal-iodine formulations varying in particle size and polyethylene glycol coating were fabricated, and shown to stably encapsulate the iodine compound. In vitro uptake studies using optical and CT imaging in the RAW264.7 macrophage cell line identified the formulation that promoted maximal uptake. Dual-energy CT imaging using this formulation in Apolipoprotein E deficient (ApoE-/-) mice (n=8) and control C57BL/6 mice (n=6) followed by spectral decomposition of the dual-energy images enabled imaging of the liposomes localized in the plaque. Imaging cytometry confirmed the presence of liposomes in the plaque and their co-localization with a small fraction (~2%) of the macrophages in the plaque.
Conclusions-The results demonstrate the feasibility of imaging macrophage-rich atherosclerotic plaques using a liposomal-iodine nanoparticle contrast agent and dual-energy CT.
- Received March 5, 2012.
- Accepted January 3, 2013.
- Copyright © 2013, Circulation: Cardiovascular Imaging