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

Abstract

18 F-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 18 F-FDG uptake, thus assisting coronary plaque inflammation identification. The present prospective randomized trial compared the efficacies of different interventions for suppressing myocardial 18 F-FDG uptake. We also investigated whether circulating free fatty acid (cFFA) levels predicted the magnitude of myocardial 18 F-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 18 F-FDG injection to evaluate the impact of fatty acid loading on myocardial 18 F-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 18 F-FDG. Myocardial uptake suppression was assessed using a qualitative visual scale and by measuring the myocardial maximum standardized uptake value (SUV max ). Insulin, glucose, and cFFA were serially measured. Results: The qualitative visual scale showed good myocardial 18 F-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 5 0.09). SUV max did not significantly differ between groups (P 5 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 5 0.011). We found an inverse correlation between cFFA level (measured at 18 F-FDG injection) and the SUV max (R 5 0.61). Receiver-operating-characteristic curve analysis identified 0.65 mmol/L cFFA as the best cutoff value to predict adequate 18 F-FDG uptake suppression (positive predictive value, 89%). Conclusion: A high-fat low-carbohydrate meal followed by a 12-h fasting period effectively suppressed myocardial 18 F-FDG uptake in most subjects. Neither complementary fatty acid loading nor verapamil administered 1 h before 18 F-FDG injection conferred any additional benefit. Myocardial 18 F-FDG uptake was inversely correlated with cFFA level, representing an interesting way to predict myocardial 18 F-FDG uptake suppression.

Joint SNMMI–ASNC expert consensus document on the role of 18F-FDG PET/CT in cardiac sarcoid detection and therapy monitoring

“…57 A strategy of adding a high-fat beverage to the high-fat, low-carbohydrate diet just before administering the 18 F-FDG has also been explored but does not appear to have additive benefit. [57][58][59][60] On the basis of our clinical experience and the available literature, nonspecific myocardial uptake may be observed in up to 20% of patients despite various dietary preparations. 52 Table 3 provides dietary recommendations for patients before undergoing 18 F-FDG PET for CS.…”

“…66 One study explored the use of calcium channel blockade with verapamil to improve myocardial suppression, but verapamil had no clear benefit over other preparations. 58 Performing 18 F-FDG PET on hospitalized patients can be challenging. Special care must be taken to avoid inadvertent carbohydrate intake and dextrose in intravenous fluids and medications (e.g., intravenous UFH infusions, antibiotic infusions, peritoneal dialysis fluids, intravenous antiarrhythmic infusions, or total parenteral nutrition).…”

Challenges of cardiac inflammation imaging with F-18 FDG positron emission tomography

“…Demeure and colleagues demonstrated similar success in suppressing myocardial FDG uptake (89%) in 9 volunteers pre-treated with oral Verapamil (120 mg) 1 hour before FDG injection who also ate a high-fat lowcarbohydrate meal, followed by a 12-h fasting period when compared to 9 other volunteers who only ate a highfat low-carbohydrate meal, followed by a 12-hour fasting period without verapamil premedication. 19 In conclusion, since patient preparation has such an important role in the determining cardiac FDG PET image quality, the dietary, fasting, and exercise recommendations should be specified in a detailed information sheet, reviewed with the patient and/or caregiver, and reinforced prior to scan date and confirmed for compliance on day of scan. Any deviation from written patient instructions should result in study cancelation and rescheduling to avoid the possibility of inadequate suppression of normal cardiac FDG uptake.…”

Optimizing FDG-PET/CT imaging of inflammation in atherosclerosis

“…12 However, as Gholami et al note more comparative studies on the effects of different diet interventions and pre-scan glucose levels on the atherosclerotic uptake of 18F-FDG would be still needed.…”

“…16 There are ongoing efforts to improve 18F-FDG-PET of coronary plaques, such as application of diet interventions to suppress myocardial glucose uptake 12 and motion correction using respiratory and ECG signals. 17 This should open possibilities to study how well 18F-FDG uptake in the coronaries and peripheral arteries correlates with each other, and thus whether peripheral artery 18F-FDG-PET is appropriate as a surrogate of coronary artery inflammation.…”