Superparamagnetic iron oxide-enhanced MRI of atherosclerotic plaques in Watanabe hereditable hyperlipidemic rabbits.
Invest Radiol
; 35(8): 460-71, 2000 Aug.
Article
em En
| MEDLINE
| ID: mdl-10946973
ABSTRACT
RATIONALE AND OBJECTIVES:
Inflammatory atherosclerotic plaques are characterized by increased endothelial permeability and multiple macrophages. Blood-pool MRI contrast agents like superparamagnetic iron oxide (SPIO) have an affinity for the monocyte-macrophage system and thus, may label inflammatory plaques. The objective was to demonstrate SPIO uptake in plaques of atherosclerotic rabbits by MRI and histology.METHODS:
Aortas of anesthetized Watanabe hereditable hyperlipidemic rabbits were studied with a moderately T2*-weighted gradient-echo sequence at 1.5 T. Four groups of five animals each were studied (1) without ultrasmall SPIO (carboxydextran coating; particle size, 25 nm; estimated plasma half-life, 6 hours) or with imaging after intravenous injection of SPIO at a dose (micromol Fe/kg) and postcontrast time delay (hours) of 50/8 (2), 50/24 (3), or 200/48 (4). In vivo MRI was compared with corresponding ex vivo histological iron stains.RESULTS:
Animals receiving 200 micromol Fe/kg demonstrated areas of focal signal loss clearly confined to the aortic wall on a mean of 24 +/- 9 (31% +/- 11%) of 76 +/- 5 images compared with 0 +/- 0 of 76 +/- 5 images in controls (P = 0.009). The number of images with this finding in groups 2 and 3 was not significantly different compared with controls. By microscopy, SPIO-iron was seen in the endothelial cells and subendothelial intimal macrophages of atherosclerosis-prone aortic wall segments. Atherosclerotic lesions demonstrating iron uptake also showed a high macrophage content.CONCLUSIONS:
SPIO accumulates in aortic plaques of atherosclerotic rabbits, producing a characteristic MRI finding. As SPIO accumulates in plaques with increased endothelial permeability and a high macrophage content, two established features of plaque inflammation, it may have a potential for noninvasive assessment of inflammatory atherosclerotic plaques.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Doenças da Aorta
/
Óxidos
/
Arteriosclerose
/
Imageamento por Ressonância Magnética
/
Meios de Contraste
/
Ferro
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2000
Tipo de documento:
Article