Suppression of myocardial FDG-uptake for vulnerablecoronary plaque imaging: Is fatty acid loading or the use ofcalcium channel blockers really needed?

Demeure, Fabian [UCL] Hanin, François-Xavier [UCL] Bol, Anne [UCL] Sprimont, Pierre [UCL] Gerber, Bernhard [UCL] Pasquet, Agnes [UCL] Vanoverschelde, Jean-Louis [UCL] Vancraeynest, David [UCL]

Background: 18F-FDG-PET/CT is a promising approach for imaging atherosclerotic plaque inflammation. However, to image coronary plaque inflammation, this application requires the suppression of background signal from adjacent myocardium. To this Aim, overnight fasting, fatty acids loading and calcium channel blocker (CCB) treatment have been proposed. Aim: To compare the efficacy of different interventions in suppressing myocardial FDG-background in a randomized prospective trial. Methods: 36 healthy volunteers (mean age 25.5±5.1 years) were randomized to 4 different types of intervention after 12 hours overnight fasting preceded by a high fat-low carbohydrate (HFLC) meal. Group 1 did not receive any additional preparation and served as reference. Group 2 and group 3 consumed 1hour before FDG-injection respectively, a high fat solution containing 43.8 g of lipids (Ketocal®), or 50 mL of olive oil, to evaluate the additive value of fatty acid loading on myocardial FDG-uptake suppression. Group 4 received 120 mg of Verapamil PO. In all groups, PET/CT of the heart (Philips Gemini-TF) was performed 60 minutes after injection of 370 MBq of 18F-FDG. Images were acquired for 5 minutes per bed position and the myocardial uptake suppression was assessed either by using a qualitative visual scale (QVS) and by measuring the maximum standardized uptake value (SUVmax) at the level of the papillary muscle. Results QVS of myocardial background suppression was similar in all groups of volunteers (0.8±1.1, 1.3±1.4, 1.4±1.2, 0.9±0.9, for groups 1-4 repectively, p=0.28 NS by χ2 test). Good myocardial background suppression (i.e. QVS 0 or 1) was observed in respectively 8/9, 5/9, 4/9 and 8/9 subjects of group 1,2,3 and 4 (p=0.08). Myocardial SUVmax tended to be lower in group 1 (2.3±0.8) than in the 3 other groups ( 4.6±3.0, 5.5±5.1, 3.0±2.7 respectively), however differences were not statistically significant (p=0.18 by ANOVA). Myocardial SUVmax of volunteers from the reference group (2.3±0.8) was lower than that of 100 consecutive patients who underwent FDG PET for oncological diagnosis after overnight fasting only (6.8±4.8, p=0.045). Conclusion: A HFLC meal followed by a fast of 12 hours before FDG injection allows to obtain a good myocardial FDG-uptake suppression in 90% of subjects. Fatty acid loading or Verapamil 1 hour before FDG injection did not confer any additional benefit.