Correlation between myocardial blood flow and fasting glucose metabolism in ischemic heart disease. Quantitative assessment by nitrogen-13 ammonia and fluorine-18 fluorodeoxyglucose positron emission tomography.

Abstract

Ischemic myocardium avidly incorporates fluorine-18 fluorodeoxyglucose (F-18 FDG) in the fasting state, in contrast to the relative absence of F-18 FDG uptake in normal myocardium with sufficient blood flow in the fasting state. Although many studies have attempted to use F-18 FDG uptake to discriminate ischemic but viable myocardium from scarred myocardium, little is known clinically about the correlation between blood flow and F-18 FDG uptake in ischemic myocardium. We studied the critical level of blood flow that causes avid F-18 FDG uptake in myocardium in 9 patients. All patients had angiographically proven ischemic heart disease but no diabetes. Regional myocardial blood flow (RMBF) was measured quantitatively by positron emission tomography (PET) using nitrogen-13 ammonia in the resting state, in which the normal value was 80.2 +/- 13.0 ml/min/100 cm3. The F-18 FDG uptake in myocardium was assessed with the differential uptake ratio (DUR) scale. We constructed circumferential profiles of radioactivity uptake in myocardium for each study, and chose 780 sections of myocardium in which the relation between the two factors could be analyzed. In moderately ischemic to normal myocardium with RMBF of 50 to 90 ml/min/100 cm3, RMBF and F-18 FDG uptake were negatively correlated (r = -0.44, p < 0.01). When RMBF was 50 to 60 ml/min/100 cm3 (n = 121), the peak DUR value of F-18 FDG uptake was 4.0 +/- 2.0. The two factors were not correlated when RMBF was less than 50 ml/min/100 cm3 or 90 ml/min/100 cm3 or higher. Our results suggest that RMBF and F-18 FDG uptake values as measured with PET may provide valuable information on the possible benefit of intervention in ischemic heart disease.