Prospective CT angiography can reduce radiation dose below that of retrospective CT angiography with dose modulation, while maintaining image quality and the ability to assess luminal obstructions in patients with heart rates of less than 75 beats per minute.

Sixty-four-slice CT angiography demonstrates a higher prevalence of NCPs with vulnerable characteristics in patients with ACS as compared with stable clinical presentation.

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Purpose Inflammation and angiogenesis are important contributors to vascular disease. We evaluated imaging both of these biological processes, using Arg–Gly–Asp (RGD)-conjugated human ferritin nanoparticles (HFn), in experimental carotid and abdominal aortic aneurysm (AAA) disease. Procedures Macrophage-rich carotid lesions were induced by ligation in hyperlipidemic and diabetic FVB mice (n=16). AAAs were induced by angiotensin II infusion in apoE−/− mice (n=10). HFn, with or without RGD peptide, was labeled with Cy5.5 and injected intravenously for near-infrared fluorescence imaging. Results RGD-HFn showed significantly higher signal than HFn in diseased carotids and AAAs relative to non-diseased regions, both in situ (carotid: 1.88±0.30 vs. 1.17±0.10, p=0.04; AAA: 2.59±0.24 vs. 1.82±0.16, p=0.03) and ex vivo. Histology showed RGD-HFn colocalized with macrophages in carotids and both macrophages and neoangiogenesis in AAA lesions. Conclusions RGD-HFn enhances vascular molecular imaging by targeting both vascular inflammation and angiogenesis, and allows more comprehensive detection of high-risk atherosclerotic and aneurysmal vascular diseases.

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Increased VAT area was significantly associated with NCP burden and vulnerable characteristics identified by CTA. Our findings may explain the excessive cardiovascular risk in patients with visceral adiposity, and support the potential role of CTA to improve risk stratification in such patients.

BackgroundMacrophages are critical contributors to atherosclerosis. Single-walled carbon nanotubes (SWNTs) show promising properties for cellular imaging and thermal therapy, which may have application to vascular macrophages.Methods and ResultsIn vitro uptake and photothermal destruction of mouse macrophage cells (RAW264.7) were performed with SWNTs (14.7 nmol/L) exposed to an 808-nm light source. SWNTs were taken up by 94±6% of macrophages, and light exposure induced 93±3% cell death. In vivo vascular macrophage uptake and ablation were then investigated in carotid-ligated FVB mice (n=33) after induction of hyperlipidemia and diabetes. Two weeks postligation, near-infrared fluorescence (NIRF) carotid imaging (n=12) was performed with SWNT-Cy5.5 (8 nmol of Cy5.5) given via the tail vein. Photothermal heating and macrophage apoptosis were evaluated on freshly excised carotid arteries (n=21). NIRF of SWNTs showed higher signal intensity in ligated carotids compared with sham, confirmed by both in situ and ex vivo NIRF imaging (P<0.05, ligation versus sham). Immunofluorescence staining showed colocalization of SWNT-Cy5.5 and macrophages in atherosclerotic lesions. Light (808 nm) exposure of freshly excised carotids showed heating and induction of macrophage apoptosis in ligated left carotid arteries with SWNTs, but not in control groups without SWNTs or without light exposure.ConclusionsCarbon nanotubes accumulate in atherosclerotic macrophages in vivo and provide a multifunctional platform for imaging and photothermal therapy of vascular inflammation.

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