FDG-PET Can Distinguish Inflamed From Non-Inflamed Plaque in an Animal Model of Atherosclerosis

OBJECTIVES: The presence of activated macrophages is an important predictor of atherosclerotic plaque rupture. In this study, our aim was to determine the accuracy of (18)F- fluorodeoxyglucose (FDG) microPET imaging for quantifying aortic wall macrophage content in a rabbit model of atherosclerosis.

METHODS: Rabbits were divided into a control group and two groups post aortic balloon injury: 6 months high-cholesterol diet (HC); and 3 months HC followed by 3 months low-cholesterol diet plus statin (LCS). In vivo and ex vivo microPET, ex vivo well counting and histological quantification of the atherosclerotic aortas were performed for all groups.

RESULTS: Macrophage density was greater in the HC group than the LCS group (5.1 +/- 1.4% vs. 0.6 +/- 0.7%, P = 0.001) with a trend towards greater macrophage density in LCS compared to controls (P = 0.08). There was a strong correlation across all groups between macrophage density and standardized uptake value (SUV) derived from ex vivo microPET (r = 0.95, P = 0.001) and well counting (r = 0.96, P = 0.001). Ex vivo FDG SUV was significantly different between the three groups (P = 0.001). However, the correlation between in vivo microPET FDG SUV and macrophage density was insignificant (r = 0.16, P = 0.57) with no statistical differences in FDG SUV seen between the three groups.

CONCLUSIONS: This study confirms that in an animal model of inflamed and non-inflamed atherosclerosis, significant differences in FDG SUV allow differentiation of highly inflamed atherosclerotic aortas from those stabilized by statin therapy and low cholesterol diet and controls. Brett Maher Womens Jersey

PMID: 19784796

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2 Comments

  1. Interesting proof-of-concept data; found in an animal model with a small number of observations.
    It will be important to compare plaque burden and plaque activity in the context of plaque progression and regression.

  2. One of the strongest (or probably the strongest) aspects of the study is that, although in a small number of animals, the authors compared the quantitative accuracy of in vivo small animal PET to both ex vivo PET and gamma well counting, then correlating this findings with plaque histology.

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