18 F-Choline Images Murine Atherosclerotic Plaques Ex Vivo

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Abstract
Objective— Current imaging modalities of atherosclerosis mainly visualize plaque morphology. Valuable insight into plaque biology was achieved by visualizing enhanced metabolism in plaque-derived macrophages using 18 F-fluorodeoxyglucose ( 18 F-FDG). Similarly, enhanced uptake of 18 F-fluorocholine ( 18 F-FCH) was associated with macrophages surrounding an abscess. As macrophages are important determinants of plaque vulnerability, we tested 18 F-FCH for plaque imaging. Methods and Results— We injected 18 F-FCH (n=5) or 18 F-FDG (n=5) intravenously into atherosclerotic apolipoprotein E-deficient mice. En face measurements of aortae isolated 20 minutes after 18 F-FCH injections demonstrated an excellent correlation between fat stainings and autoradiographies ( r =0.842, P 18 F-FCH. In contrast, radiotracer uptake 20 minutes after 18 F-FDG injections correlated less with en face fat stainings ( r =0.261, P 18 F-FCH and 14 C-FDG (n=3) showed that 18 F-FCH uptake correlated better with fat staining ( r =0.740, P r =0.740, P 14 C-FDG (fat: r =0.236, P =0.29 and CD68 staining: r =0.352, P =0.11), respectively. Conclusions— 18 F-FCH identifies murine plaques better than 18 F-FDG using ex vivo imaging. Enhanced 18 F-FCH uptake into macrophages may render this tracer a promising candidate for imaging plaques in patients.