Imaging of early inflammation in low-to-moderate carotid stenosis by 18-FDG-PET

It is not clear if 18FDG-PET can be useful for detection of inflammation in low to moderate carotid stenosis. We studied 15 patients scheduled for endarterectomy with contralateral carotids with less than 50% stenosis. 18-FDG-PET was performed prior to CEA and 3 months following surgery. FDG-uptake values were calculated based on maximum standardized uptake value (SUV) and corresponding uptake ratios. We confirmed by CD68 macrophage staining that FDG accumulation corresponds to active inflammation (R= 0.8 p<0.005). We found significant correlation between the FDG-uptake in the carotids scheduled for CEA and contralateral carotids with low to moderate stenosis ( R= 0.9 p<0.001). The FDG uptake ratio in the contralateral arteries remained stable on the follow-up imaging (1.15+/-0.2 vs. 1.14+/-0.1; R=0.7 p=0.006). We did not find correlation between FDG uptake and symptomatic or asymptomatic patients, degree of carotid stenosis and vascular risk factors. This is a prospective, preliminary in vivo study demonstrating that low to moderate carotid atherosclerosis can be detected using 18-FDG-PET imaging and highlights the truly systemic nature of atherosclerosis.