Effect of aging and smoking on FDG-uptake in atherosclerotic plaques assessed by multiple-time-point PET/CT imaging

Objectives To prospectively determine the relation between aging, smoking, and FDG uptake in atherosclerotic plaque in the aorta by multiple-time-point (MTP) imaging.

Methods Ten of 31 patients with lung cancer were selected for this analysis. Each patient underwent MTP PET/CT imaging at one, two, and three hours following FDG administration. FDG-uptake in atherosclerotic plaques, quantified as weighted average SUVmean (aSUVmean) [∑ (SUVmean x surface area x slice thickness) / total vessel volume], was determined in the aorta by placing ROIs around the aortic wall on every slice (5 mm) of the attenuation corrected PET/CT images. Correction for the mean venous blood pool activity was performed by subtracting the venous activity from the arterial activity. A multiple regression model was fitted to correct for possible confounding by other cardiovascular risk factors.

Results Preliminary data of 10 patients with an average age of 64 ± 10 years (range 51 - 80) showed no significant correlation between age and blood pool subtracted aSUVmean utilizing images acquired at one (β = .006; P = .2) and two (β = .004; P = .1) hours after FDG administration. However, a significant correlation was noted on images taken three hours after injection of the compound (β = .008; P = .045). Furthermore, a significant difference in FDG-uptake was noted between smokers (n = 7) and non-smokers (n = 3) at the first (β = .037; P = .01), second (β = .059; P = .005), and third hour (β = .042; P = .009) after FDG administration.

Conclusions These data show that aging and smoking result in increased FDG uptake in atherosclerotic plaque in the aorta. This effect appears to become more significant at three hours after FDG administration. Delayed FDG uptake in atherosclerotic plaque and declining levels of FDG in the blood likely account for this important observation. These data support the benefits of MTP imaging in assessing atherosclerosis in any setting