Glucose metabolism in reperfused myocardium measured by [2-F-18] 2-fluorodeoxyglucose and PET

Objective: [2-F-18] 2-fluorodeoxyglucose (FDG) is widely used to trace gluc ose metabolism for cardiac imaging with positron emission tomography. Becau se the transport and phosphorylation rates differ for glucose and FDG, a lu mped constant (LC) is used to correct for these differences, The effects of ischemia and reperfusion on the LC in vivo are unknown, To determine the v alidity of FDG as a tracer of glucose metabolism in post-ischemic myocardiu m in vivo, the relationship between glucose uptake (GU) and FDG metabolic r ate (FDG-MR) was assessed early post-reperfusion following a transient isch emic event. Methods: FDG metabolic rate, measured with FDG and PET, was; co mpared to invasive measurements of substrate metabolism in reperfused and g lobal myocardium of dogs subjected to 25 min ischemia and 2 h reperfusion, Results: The FDG metabolic rate was decreased 20+/-4% in reperfused relativ e to remote myocardium, Glucose oxidation and lactate uptake were also decr eased in reperfused relative to global myocardium, by 26+/-6% and 60+/-8% r espectively. Glucose uptake did not differ significantly between reperfused and global myocardium, A linear correlation between FDG metabolic rate and glucose uptake was found in both reperfused and remote myocardium, Estimat es of the LC from the slopes of the regression lines were similar in repel- fused and remote myocardium, 1.25 and 1.44 respectively, and did nor differ significantly from the LC determined in control dogs, 1.1. Conclusions: We conclude that the FDG metabolic rate continues to correlate well with gluc ose metabolism in reperfused myocardium. While FDG metabolic rate was modes tly decreased in the absence of a significant change in glucose uptake, lar ge alterations in the LC are not found 2 h post-reperfusion in vivo. (C) 20 00 Elsevier Science BN. All rights reserved.