Effects of age and cardiovascular risk factors on ¹⁸F-FDG PET/CT quantification of atherosclerosis in the aorta and peripheral arteries

Objective: To quantify fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) uptake in the aorta and peripheral arteries and assess the variation of ¹⁸F-FDG uptake with age and cardiovascular risk factors. Methods: The subject population of this retrospective study comprises melanoma patients who underwent wholebody ¹⁸F-FDG PET/CT scans. The patients' medical records were examined for cardiovascular risk factors and for a history of coronary artery disease or peripheral artery disease. Fluorine-18-FDG uptake in the peripheral arteries (iliac and femoral) and aorta was semi-quantified as a weighted-average mean standardized uptake value (wA-SUVmean), while background noise was accounted for by measuring mean venous blood pool SUV (V-SUVmean) in the superior vena cava. Atherosclerosis was semi-quantified by the tissue-to-background ratio (TBR) (wA-SUVmean divided by V-SUVmean). A regression model and ttest were used to evaluate the effect of age and location on the degree of atherosclerosis. To assess the effect of cardiovascular risk factors on atherosclerotic burden, the wA-SUVmean of patients with at least one of these risk factors was compared to that of patients without any risk factors. Results: A total of 76 patients (46 men, 30 women; 22-91 years old) were included in this study. The average TBR of the aorta and peripheral arteries were 2.68 and 1.43, respectively, and increased with age in both locations. In regression analysis, the beta coefficients of age for TBR in the aorta and peripheral arteries were 0.55 (P18F-FDG uptake was observed in the peripheral arteries and aorta with increasing age. Cardiovascular risk factors were significantly correlated with ¹⁸F-FDG uptake in aorta. The early detection of atherosclerosis with ¹⁸F-FDG PET may allow for the initiation of preventative interventions prior to the manifestation of significant structural abnormalities or symptoms of disease.