Optimizing myocardial metabolism for fluorine-18 fluorodeoxyglucose positron emission tomography imaging of cardiac inflammation

Abstract

Inflammation-related hot spot imaging along with suppression of physiologic myocardial glucose metabolism forms the basis of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) imaging of inflammatory cardiomyopathies, infections of intracardiac devices, and prosthetic valves and vulnerable coronary plaques. Adequate attenuation of physiologic myocardial glucose uptake that ensures high-quality FDG-PET images, however, can be challenging, especially since glucose can be physiologically taken up by the cardiomyocytes under certain conditions. In order to maximize suppression of normal glucose uptake, a number of different interventions have been proposed and are utilized by PET laboratories, without there being a consensus on the most effective one.To better appreciate the different suppression techniques available, a basic understanding of myocardial metabolism is essential.1,2 A variety of different metabolic substrates can be utilized by the myocardium depending on fasting vs post-meal state and underlying viability. More specifically, during fasting state, there is a predominant (90%) utilization of free fatty acids (FFAs) and to a much lesser extent glucose and lactate.