A Randomized Trial on the Optimization of 18F-FDG Myocardial Uptake Suppression: Implications for Vulnerable Coronary Plaque Imaging

18F-FDG PET/CT can be used to detect arterial atherosclerotic plaque inflammation. However, avid myocardial glucose uptake may preclude its use for visualizing coronary plaques. Fatty acid loading or calcium channel blockers could decrease myocardial 18F-FDG uptake, thus assisting coronary plaque inflammation identification. The present prospective randomized trial compared the efficacies of different interventions for suppressing myocardial 18F-FDG uptake. We also investigated whether circulating free fatty acid (cFFA) levels predicted the magnitude of myocardial 18F-FDG uptake. Methods: Thirty-six volunteers ate a high-fat low-carbohydrate meal, followed by a 12-h fasting period. They were then randomized to 1 of 4 intervention groups. Group 1 received no additional preparation and served as a reference. Groups 2 and 3, respectively, received a commercial high-fat solution containing 43.8 g of lipids or 50 mL of olive oil 1 h before 18F-FDG injection to evaluate the impact of fatty acid loading on myocardial 18F-FDG uptake. Group 4 received verapamil to evaluate the effect of calcium channel blockers. Cardiac PET/CT was performed after administration of 370 MBq of 18F-FDG. Myocardial uptake suppression was assessed using a qualitative visual scale and by measuring the myocardial maximum standardized uptake value (SUVmax). Insulin, glucose, and cFFA were serially measured. Results: The qualitative visual scale showed good myocardial 18F-FDG uptake suppression in 8 of 9, 5 of 9, 4 of 9, and 8 of 9 subjects of groups 1, 2, 3, and 4, respectively (P = 0.09). SUVmax did not significantly differ between groups (P = 0.17). Interestingly, cFFA levels were higher in volunteers with good suppression (0.80 ± 0.31 mmol/L) than in those with poor suppression (0.53 ± 0.15 mmol/L; P = 0.011). We found an inverse correlation between cFFA level (measured at 18F-FDG injection) and the SUVmax (R = 0.61). Receiver-operating-characteristic curve analysis identified 0.65 mmol/L cFFA as the best cutoff value to predict adequate 18F-FDG uptake suppression (positive predictive value, 89%). Conclusion: A high-fat low-carbohydrate meal followed by a 12-h fasting period effectively suppressed myocardial 18F-FDG uptake in most subjects. Neither complementary fatty acid loading nor verapamil administered 1 h before 18F-FDG injection conferred any additional benefit. Myocardial 18F-FDG uptake was inversely correlated with cFFA level, representing an interesting way to predict myocardial 18F-FDG uptake suppression.