Effect of regional hyperemia on myocardial uptake of 2-deoxy-2-[¹⁸F]fluoro-d-glucose

Abstract

2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) may be used to predict glucose kinetics when the factor relating differences in transport and phosphorylation between compounds remains constant ("lumped constant"). It is not clear whether hyperemia alters that factor. In anesthetized swine, myocardial FDG uptake was estimated by positron emission tomography, during an intracoronary infusion of either adenosine, ATP, or bradykinin (40 microg x kg(-1) x min(-1), 40 microg x kg(-1) x min(-1), and 2 nmol x kg(-1) x min(-1), respectively; n = 6 for all groups). In controls during normal perfusion (n = 6), FDG uptake was 0.78 +/- 0.32 micromol x g(-1) x min(-1), whereas glucose uptake by Fick was 0.71 +/- 0.25 micromol x g(-1) x min(-1) (r = 0.73; P < 0.05). Adenosine increased blood flow from 1.29 +/- 0.43 to 4.80 +/- 2.19 ml x g(-1) x min(-1) (P < 0.05) and glucose uptake from 1.16 +/- 1.10 to 3.35 +/- 2.12 micromol x g(-1) x min(-1) (P < 0.05), whereas FDG uptake in the hyperemic region was lower than remote regions (0.46 +/- 0.29 and 0.95 +/- 0.55 micromol x g(-1) x min(-1), respectively; P < 0.05). In the ATP and bradykinin groups, blood flow increased four- and twofold, respectively, with no net change in glucose uptake. FDG uptake in the hyperemic region was also significantly lower than remote regions. For all animals, the ratio of blood flow in the hyperemic region relative to remote region was inversely proportional to the ratio of FDG uptake in the same regions (r(2)=0.73; P < 0.001). Because nitric oxide elaboration during hyperemia could potentially alter substrate preference and FDG kinetics, six additional swine were studied during maximal adenosine before and after intracoronary N(G)-monomethyl-L-arginine (1.5 mg/kg). Inhibition of nitric oxide had no effect on either regional myocardial substrate uptake or FDG accumulation. In conclusion, hyperemia decreased regional myocardial FDG uptake relative to normally perfused regions and this effect on the lumped constant was independent of nitric oxide.

Effect of flow and vascular heterogeneity on glucose metabolism in isolated dog hearts

“…Several other groups have recently presented warning words that absolute quantification of myocardial glucose metabolic rate by [ 18 F]FDG using PET or dedicated SPET is inaccurate (Doenst & Taegtmeyer, 1998; Marshall et al ., 1998; Botker et al ., 1999; Wiggers et al ., 1999; McFalls et al ., 2000). Especially, the ratio of tracee‐to‐tracer (lumped constant) has been carefully discussed.…”

Variability of insulin-stimulated myocardial glucose uptake in healthy elderly subjects

“…Myocardial perfusion was measured with 13 NH 3 on a separate day, to avoid the myocardial metabolic effects of inducing hyperaemic blood flow before subsequent measurements of myocardial glucose uptake [22]. On the day of the perfusion study the subjects were allowed a carbohydrate-containing breakfast, but were instructed to refrain from caffeine intake for at least 18 h prior to the study.…”