18F-FDG Cardiac Studies for Identifying Ischemic Memory

Abstract

Myocardial ischemia is associated with profound changes in substrate utilization by the myocardium for energy production. This change occurs with the onset of ischemia, but persists much longer, perhaps for several hours or even days after an episode of myocardial ischemia, which is termed ischemic memory. Recently, radiolabeled glucose analogue (Fluorine-18 labeled deoxyglucose, 18FDG) and free acid analogue (β-methyl-p-123I-iodophenyl-pentadecanoic acid, 123I-BMIPP) have been investigated to detect myocardial ischemia in stable coronary artery disease (CAD) or suspected acute coronary syndrome (ACS). These studies demonstrate that BMIPP imaging holds promise for evaluation of patients with suspected ACS in the emergency department. Exercise 18FDG imaging offers several potential advantages over conventional stress-rest perfusion imaging for the detection of CAD. Furthermore, ischemia-induced 18FDG uptake may persist for several to 24 hours in patients with stress-induced myocardial ischemia. Therefore, 18FDG may also be a useful memory marker in detection of antecedent myocardial ischemia in suspected ACS. However, some important issues about 18FDG ischemic imaging need to be further investigated. In this article the advances of myocardial ischemic imaging with 18FDG are reviewed. Several unresolved issues and the perspective of this modality are also discussed.