<sup>18</sup>F-FDG PET in Myocardial Viability Assessment: A Practical and Time-Efficient Protocol
Joyce Mhlanga, Paul-Robert Derenoncourt, Adeel Haq, Anita Bhandiwad, Richard Laforest, Barry A. Siegel, Farrokh Dehdashti, Robert J. Gropler, Thomas H. Schindler
Abstract
We assessed image quality using a practical and time-efficient protocol for intravenous glucose loading and insulin injection prior to administration of <sup>18</sup>F-fluorodeoxyglucose (<sup>18</sup>F-FDG) for PET myocardial viability evaluation in patients with ischemic cardiomyopathy, with and without type 2 diabetes mellitus. <b>Methods:</b> Metabolic preparation period (MPP) or optimal cardiac <sup>18</sup>F-FDG uptake was determined from the time of intravenous infusion of 12.5 or 25 gram of 50% dextrose to the time of <sup>18</sup>F-FDG injection. Cardiac <sup>18</sup>F-FDG image quality was evaluated according to a 5-point scoring system (5=excellent to 1=non-diagnostic) by two independent observers. In cases of disagreement, consensus was achieved in a joint reading. Fifteen patients with ischemic cardiomyopathy, who underwent oral glucose loading and i.v. insulin administration, served as reference for MPP comparisons. <b>Results:</b> 59 consecutive patients (age: 63±10yrs, men <i>n</i> = 48 and women <i>n</i> = 11) underwent rest <sup>99m</sup>Tc-tetrofosmin SPECT/CT and <sup>18</sup>F-FDG PET/CT for the evaluation of myocardial viability. FDG image quality was scored as excellent in 42%, very good in 36%, good in 17%, fair in 3%, and non-diagnostic in 2%. Comparing diabetic and non-diabetic patients, the quality scores were excellent in 29% vs. 76% , very good in 41% vs. 18%, good in 24% vs. 6%, fair in 4% vs. 0% , and non-diagnostic in 2% vs. 0%. The mean (±SD) quality score was 4.12±0.95 and overall it was better in non-diabetic than in diabetic patients (4.71±0.59 vs 3.88±0.96; p<0.0001). Notably, the average MPP was significantly less with i.v. glucose loading when compared to oral glucose loading (51±15 vs. 132±29 min; p<0.0001), paralleled by higher insulin doses (6.3 ± 2.2 vs. 2.0 ± 1.69 U; p<0.001). <b>Conclusion:</b> Using a practical and time efficient protocol for i.v. glucose loading and insulin administration prior to <sup>18</sup>F-FDG injection reduces the MPP by 61% as compared to oral glucose challenge that affords good-to-excellent image quality in 95% of ischemic cardiomyopathy patients.