FDG PET image quality during hyperinsulinemic euglycemic clamp in ischemic cardiomyopathy with and without diabetes mellitus

Abstract

Background: Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) can be utilized to assess myocardial viability. The objective of this study was to assess FDG PET image quality during the hyperinsulinemic euglycemic clamp (HE clamp) in patients with and without diabetes referred for myocardial viability assessment. Methods: Consecutive FDG PET viability scans at Mayo Clinic from June 2000Nov 2003 were reviewed retrospectively. Scans were performed using static acquisition. Image quality was visually assessed at the time of reading by two experienced observers. Image quality was also assessed by calculating the myocardium to blood pool (M/B) activity ratio (mean activity from regions of interest over normal myocardium and the LV cavity, averaged over three midventricular slices). Results: 81 of 82 FDG PET scans utilized the HE clamp; 39 Type 2 diabetics (DM2), 2 Type 1 diabetics, and 40 non-diabetics (Non-DM). By visual assessment, images were inadequate in 1 DM2 (M/B=1.6) and 1 Non-DM (M/B=1.8). All other patients (97%) had adequate images (M/B range 2.2–30.0). DM2 Non-DM P-Value Age, yrs 67.4 ± 10.3 64.8 ± 13.0 NS BM, kg/m 22 30.9 ± 5.9 27.7 ± 5.4 0.02 LVEF, % 27.3 ± 9.5 29.8 ± 11.0 NS Blood glucose before clamp, mg/dL 141.1 ± 34.6 101.7 ± 13.3 0.0001 Clamp start to FDG injection, min 155.7 ± 71.8 104.7 ± 35.1 0.0001 FDG injection to scan, min 39.8 ± 10.9 39.8 ± 16.1 NS Blood glucose during scan, mg/dL 91.6 ± 10.5 85.4 ± 13.3 0.03 Dextrose infusion during scan, mg/kg/min 3.1 ± 1.6 3.9 ± 1.6 0.02 M/B ratio 6.5 ± 4.6 8.1 ± 4.6 0.06 Conclusions: HE clamp yielded adequate image quality in >97% of both diabetic and non-diabetic patients referred for FDG PET myocardial viability assessment. HE clamp time was longer in diabetics, primarily due to higher baseline glucose and longer time until FDG injection.