Simple quantification of regional myocardial uptake of fluorine-18-deoxyglucose in the fasting condition

Quantitative measurement of myocardial uptake of fluorine-18-deoxyglucose (FDG) is required for assessing tissue viability in the fasting state due to suppressed FDG uptake in the normal myocardium. A simple FDG uptake index (% dose per 100 ml tissue) has been introduced to compare with the fractional FDG uptake in 21 patients who underwent serial arterial blood sampling (14 under fasting and 7 under post-prandial conditions) and to measure the normal range in each myocardial segment in the study of 10 normal subjects (all in the fasting condition). Since the integral of plasma FDG values correlated with the body-weight corrected injected FDG dose (r = 0.82), an excellent correlation was observed between the FDG uptake index and the fractional FDG uptake (r = 0.98) in the fasting condition. In addition, the FDG uptake index correlated well with the regional metabolic rate of glucose calculated with the Patlak graphic analysis (r = 0.99). But this correlation was different in the postprandial condition and in the fasting condition in diabetic patients. In the study of normal subjects, the FDG uptake index was slightly higher in the lateral and inferior segments, as compared to the septal and anterior segments (p less than 0.05, each). We conclude that the FDG uptake index is considered as a simple and reliable parameter for quantitative assessment of myocardial FDG uptake in the nondiabetic patients in the fasting condition. Since its uptake was heterogeneous, FDG uptake should be carefully evaluated for assessing myocardial viability by comparing normal values in each segment.