Pre-administration of caffeine anhydrous food supplement potentially improves suppression of physiologic myocardial [18F]FDG uptake: a feasibility study.

Background Positron emission tomography/Computed tomography (PET/CT) with [ ¹⁸ F]FDG has an increasingly relevant role in diagnosing and treatment management of myocardial inflammation and infection. A major confounding factor in cardiac [ ¹⁸ F]FDG PET/CT is physiological myocardial glucose uptake, which could obscure pathologic myocardial uptake in disease affected myocardium (e.g., inflammatory conditions). Despite generally accepted conventional measures such as dietary manipulation, extended fasting, and possibly additional intravenous heparin, confounding physiological myocardial [ ¹⁸ F]FDG uptake still occurs in 5–20% of the patients, and further improvement of the protocol is needed. It is proposed that these patients may benefit from additional pre-administration of caffeine anhydrous as a food supplement. Caffeine acts as an adenosine receptor antagonist, stimulating lipolysis in adipose tissue and promoting adrenergic release of epinephrine. This stimulates β AR-mediated lipolysis in adipose tissue and β AR-mediated inhibition of insulin-independent glucose transporter (GLUT) 4 expression and translocation, which reduces insulin-dependent GLUT4 myocardial [ ¹⁸ F]FDG uptake. This study aims to investigate the feasibility of using additional caffeine anhydrous pre-administration on myocardial [ ¹⁸ F]FDG uptake suppression. Results Additional administration of caffeine anhydrous before [ ¹⁸ F]FDG injection resulted in complete myocardial suppression in five out of eight patients (63%), and a near-complete suppression in two patients (25%). In all patients, there was a significant ( p  < 0.001) reduction in the overall number of segments with inadequate suppression. No significant differences ( p  > 0.05) were observed in visual and semi-quantitative measurements of extra-cardiac image quality and extra-cardiac sarcoid lesions. All monitored patient parameters remained stable, except for an expected significant ( p  < 0.001) decrease in mean heart rate before [ ¹⁸ F]FDG injection. Conclusion Pre-administration of additional caffeine anhydrous food supplement has the potency to safely improve myocardial [ ¹⁸ F]FDG uptake suppression in patients who experience inadequate myocardial [ ¹⁸ F]FDG uptake suppression following a standard HFNC diet and more than 12 hours of fasting. This potential improvement could contribute to better diagnosis and consequent treatment management of cardiac inflammation and infection in these patients. The feasibility of administering additional caffeine anhydrous is further supported by the maintenance of visual and semi-quantitative image quality, as well as good tolerability among the participants. Trial registration ISCTRP, NLOMON51725. Registered 22 December 2022, https//trialsearch.who.int/Trial2.aspx?TrialID=NLOMON51725