Abstract 13145: In Vivo Monitoring of Atherosclerotic Evolution and Detection of Vulnerable Plaque in a Rabbit Model by 18F-FDG PET/CT

Abstract

Objectives: To investigate the 18F-FDG uptakes with evolution of atherosclerotic plaques and the feasibility for detection of vulnerable plaque by PET/CT in an atherosclerotic model.

Methods: Forty-nine male NZW rabbits were randomly divided into two groups: atherosclerosis group (G-A, n=34) and statins group (G-B, n=15). All rabbits were fed a 1.5% cholesterol diet for 2 wks before balloon injury of the abdominal aorta and continued for 6 wks. Then G-A was fed with intermittent high-cholesterol diet for 10 wks, and G-B was given atorvastatin for 10 wks. At the end of 18 wks, the rabbits underwent 2 pharmacological triggerings to induce plaque rupture. In vivo PET/CT scans were performed on four time points: before cholesterol diet (scan1), at 8^th wk (scan 2), at 18^th wk (scan 3) and after triggering (scan 4). The mean standardized uptake values (SUVmean) and maximal SUV (SUVmax) were measured over the aorta. The aortic smooth muscle cell (SMC) number, macrophage number (M) and the ratio of fibrous cap to lipid core (RCC) in plaques were analyzed.

Results: The SUVmean and SUVmax were as following: 0.449±0.108 and 0.550±0.132 on scan 1; 0.694±0.117 and 0.754±0.129 on scan 2; 0.780±0.133 and 0.855±0.146 in G-A, 0.664±0.181 and 0.757±0.203 in G-B on scan 3; 1.194±0.484 and 1.338±0.558 on scan 4 (thrombosis group). The differences among these four times scans were significants (P=0.000), except the comparison between the parameters on scan 2 and those on scan 3 in G-B. The segments with thrombosis had a higher SUVmean (1.039±0.263 VS 0.782±0.197, P=0.000), a higher SUVmax (1.164±0.306 VS 0.851±0.224, P=0.000), a higher M (58.65±16.30 VS 46.41±18.88, P=0.000), and a lower RCC (0.147±0.092 VS 0.304±0.113, P=0.000), when compared with the segments without thrombosis. The SUVmean on vulnerable plaques in the pretriggered PET/CT images was higher than that of stable plaque (1.098±0.189, 0.768±0.111, P=0.000). If SUVmean≥0.9 is defined as vulnerable plaque, the sensitivity is 72.3% and the specificity is 56.6% for predicting plaque rupture.

Conclusion:¹⁸F-FDP PET/CT may become an imaging method to monitor the evolution of atherosclerosis and detect vulnerable plaques.