Objective: Atherosclerosis is a dynamic and complex process characterized by the formation and progression of plaque mediated by various pathophysiologic steps including inflammation and calcification. The present study aimed to evaluate the association between carotid 18F-sodium fluoride (NaF) and 18F-fluorodeoxyglucose (FDG) uptake with the severity of ischemic vascular brain disease on MRI in patients with carotid artery disease.
Methods: A total of 28 patients who were scheduled to undergo clinically indicated carotid endarterectomy or stenting for carotid artery disease were examined with 18F-NaF and 18F-FDG PET/CT and brain MRI. The PET/CT images were evaluated by qualitative and semiquantitative analyses. The maximum standardized uptake value (SUV) for the plaque and the average of mean SUV within the lumen of both internal jugular veins was calculated, and the target-to-blood pool ratio (TBR) was determined. The ischemic vascular brain disease on MRI was graded separately in the bilateral hemisphere as 0, 1, 2, and 3, with 0 being absent and 3 being the most severe.
Results: In two patients, only a unilateral carotid artery was analyzed because of previous indwelling stent. 18F-NaF focal uptake was observed in 50 carotid arteries. 18F-FDG focal uptake was observed in 47 carotid arteries. The mean (± SD) 18F-NaF TBR (2.93 ± 0.89) was significantly higher than the mean (± SD) 18F-FDG TBR (2.41 ± 0.84) (p < 0.001). The mean (± SD) values of 18F-NaF TBR were 2.63 ± 0.76 in grade 1, 2.90 ± 0.91 in grade 2, and 3.81 ± 0.60 in grade 3. Significant differences in 18F-NaF TBR were observed between grades 1 and 3 (p < 0.001) and grades 2 and 3 (p = 0.02). The mean (± SD) values of 18F-FDG TBR were 2.35 ± 0.77 in grade 1, 2.23 ± 0.48 in grade 2, and 2.87 ± 1.32 in grade 3. No significant differences in 18F-FDG TBR were noted between any of the ischemic vascular brain disease grades.
Conclusions: These preliminary results suggest that carotid 18F-NaF uptake in patients with carotid artery disease may be associated with the severity of the ischemic vascular brain disease observed on MRI.
Keywords: 18F-FDG; 18F-NaF; Atherosclerosis; Carotid artery; PET.