18F-FDG PET in Myocardial Viability Assessment: A Practical and Time-Efficient Protocol

We assessed image quality using a practical and time-efficient protocol for intravenous glucose loading and insulin injection before administraischemic cardiomyopathy (ICM), with and without type 2 diabetes mellitus. Methods: The metabolic preparation period (MPP) or optimal cardiac 18F-FDG uptake was determined from the time of intravenous infusion of 12.5 or 25 g of 50% dextrose to the time of 18F-FDG injection. Cardiac 18F-FDG image quality was evaluated according to a 5-point scoring system (from 5, excellent, to 1, nondiagnostic) by 2 independent observers. In cases of disagreement, consensus was achieved in a joint reading. Fifteen patients with ICM who underwent oral glucose loading and intravenous insulin administration served as a reference for MPP 48 men and 11 women) underwent rest 99mTc-tetrofosmin SPECT/CT and 18F-FDG PET/CT for the evaluation of myocardial viability. 18F-FDG image quality was scored as excellent in 42%, very good in 36%, good in 17%, fair in 3%, and nondiagnostic in 2%. When diabetic and nondiabetic patients were compared, the quality scores were excellent in 29% versus 76%, very good in 41% versus 18%, good in 24% versus 6%, fair in 4% versus 0%, and nondiagnostic in 2% versus 0%. The mean (??SD) quality score was 4.12 ?? 0.95, and overall it was better in nondiabetic than in diabetic patients (4.71 ?? 0.59 vs. 3.88 ?? 0.96; P < 0.0001). Notably, the average MPP was significantly less with intravenous glucose loading than with oral glucose loading (51 ?? 15 min vs. 132 ?? 29 min; P < 0.0001), paralleled by higher insulin doses (6.3 ?? 2.2 U vs. 2.0 ?? 1.69 U; P < 0.001). Conclusion: Using a practical and time-efficient protocol for intravenous glucose loading and insulin administration before 18F-FDG injection reduces the MPP by 61% as compared with an oral glucose challenge and affords good-to-excellent image quality in 95% of ICM patients.