Atherosclerosis : contrast-enhanced MR imaging of vessel wall in rabbit model-comparison of gadofosveset and gadopentetate dimeglumine

Purpose: To investigate the potential of gadofosveset for contrast material-enhanced magnetic resonance (MR) imaging of plaque in a rabbit model of atherosclerosis. Materials and Methods:All experiments were approved by the animal ethics committee. Thirty-one New Zealand White rabbits were included in one of four study groups: animals with atherosclerosis imaged with gadofosveset (n = 10) or gadopentetate dimeglumine (n = 7) and control animals imaged with gadofosveset (n = 7) or gadopentetate dimeglumine ( n = 7). Aortic atherosclerosis was induced through endothelial denudation combined with a cholesterol-enriched diet. Control rabbits underwent a sham surgical procedure and received a regular diet. After 8 weeks, pre- and post- contrast T1-weighted MR images of the aortic vessel wall were acquired. Relative signal enhancement was determined with dedicated software. Statistical analysis was performed by using a generalized linear mixed model. Immunohistochemical staining with CD31 and albumin was used to assess microvessel density and the albumin content of the vascular wall. Group differences were analyzed by using a ¿2 test. Gadofosveset spatial distribution and content within the vessel wall were determined with proton-induced x-ray emission (PIXE) analysis. Results: Postcontrast signal enhancement was significantly greater for atherosclerotic than for control animals imaged with gadofosveset (P =.022). Gadopentetate dimeglumine could not enable discrimination between normal and atherosclerotic vessel walls (P =.428). PIXE analysis showed higher amounts of gadopentetate dimeglumine than gadofosveset in both atherosclerotic and normal rabbit aortas. Immunohistochemical staining revealed the presence of albumin and increased microvessel density in the vascular walls of atherosclerotic rabbits. Conclusion: These results suggest that gadofosveset can be used to differentiate between atherosclerotic and normal rabbit vessel walls. © RSNA, 2009