Atherosclerotic plaques are more prevalent in infradiaphragmatic aorta than thoracic aorta as revealed by FDG-PET/CT

1835 Objectives To demonstrate that inflammatory atherosclerotic plaques are more prevalent in the sub-diaphragmatic than in supra-diaphragmatic regions of aorta as visualized by FDG-PET. Methods Ten of 32 patients, who underwent PET/CT imaging for lung cancer, were selected for this analysis. Each patient underwent multiple-time-point PET/CT imaging at one, two, and three hours following the administration of FDG. Atherosclerotic plaque FDG-uptake, quantified as weighted average SUVmean (aSUVmean), was determined by placing ROIs around the arterial wall from the cardiac origin of the aorta down to the level of the aortic bifurcation. To calculate the aortic wall FDG uptake, we subtracted the aSUVmean of mean venous blood pool from the aorta activity (Δ SUVmean). The Δ aSUVmean of the supra- and infradiaphragmatic aorta was calculated and compared. Results Preliminary data of 10 patients with a mean age of 63 ± 10 showed that Δ SUVmean was higher in infradiaphragmatic aorta compared to the supradiaphragmatic aorta in all three time-point, but was significant only in three hour time point images (Δ SUVmean = 0.52, 0.72 in supra- and infradiaphragmatic aorta, respectively) (P Conclusions The preliminary data show increased FDG uptake in the infradiaphragmatic aorta compared to the supradiaphragmatic aorta. This effect appears to read statistical significance after three hours after administration of FDG. Delayed FDG uptake in atherosclerotic plaques and declining levels of FDG in the blood likely account for this important observation. These data support the benefit of delayed-time-point imaging in assessing atherosclerosis in any setting