Quantifying Myocardial Glucose Use with PET

In this study, we compared the accuracy of the rate of myocardial glucose use (rMGU) measured using PET and 1-11C-glucose with the rate measured using PET and the more conventional tracer 18F-FDG. Methods: PET measurements of myocardial tracer uptake (K, in mL/g/min) and rMGU (in nmol/ g/min) were obtained with 1-11C-glucose and 18F-FDG in 21 dogs using kinetic modeling and the Patlak graphical method, respectively. Eighteen dogs were studied during hyperinsulinemic–euglycemic clamp performed either at rest or combined with phenylephrine, dobutamine, intralipid infusion, or intralipid infusion and dobutamine. Three dogs were studied during intralipid infusion alone under resting conditions. Arterial–coronary sinus sampling was performed to measure the K of both tracers (n 14) and rMGU by the Fick method (n 21). Results: PET-derived values for K from either 1-11C-glucose or 18F-FDG correlated closely with directly measured tracer K values (glucose: y 0.98x 0.01, r 0.79, P 0.001; 18F-FDG: y 0.74x 0.03, r 0.77, P 0.001). In contrast, correlation with K values of unlabeled glucose measured directly was better for 1-11C-glucose (y 0.92x 0.02, r 0.96, P 0.0001) than for 18F-FDG (y 0.66x 0.05, r 0.72, P 0.01) (P 0.001 for comparison of correlation coefficients). As a consequence, PET-derived values for rMGU correlated more closely with Fickderived measurements of unlabeled glucose using 1-11C-glucose (y 0.82x 168, r 0.97, P 0.0001) than with 18F-FDG (y 0.81x 278, r 0.79, P 0.001) (P 0.001 for comparison of correlation coefficients). Conclusion: Over a wide range of conditions, PET-derived measurements of rMGU are obtained more accurately with 1-11C-glucose than with 18F-FDG.