Abstract 19520: Hybrid PET/CT Imaging Five Days After Myocardial Infarction Provides Accurate Assessment of the Ischemic Area at Risk But Overestimates Myocardial Infarct Size in Swine
Introduction: Recent clinical studies suggest that fasting 18F-fluorodeoxyglucose (FDG) PET imaging may enable retrospective assessment of the ischemic area at risk (AAR) within the first week after reperfused myocardial infarction (MI). If so, hybrid PET/CT imaging combining FDG PET with delayed contrast-enhanced (DE) CT could provide accurate quantification of the AAR and infarct size in a single imaging session. We tested the accuracy of this approach in a porcine model of reperfused MI using post-mortem pathologic quantification of the AAR and infarct size.
Methods: Closed-chest, propofol-anesthetized swine (n=6) were subjected to a 1 hour mid-LAD occlusion to produce MI. PET/CT imaging (2.4±0.1 mCi FDG) was performed 5 days later following an overnight fast with intravenous heparin to suppress FDG uptake in remote myocardium. The AAR was assessed by quantifying the volume of left ventricular (LV) myocardium exhibiting ≥50% of maximal FDG uptake and compared to pathologic measurements obtained via dye injection during LAD re-occlusion at the time of sacrifice. DE CT measures of infarct size were compared to values derived from post-mortem triphenyl tetrazolium chloride (TTC) staining.
Results: Myocardial FDG uptake localized to the LAD perfusion territory and consistently exceeded uptake in remote areas of the LV (LAD vs. remote: 3.9±0.2 vs. 1.7±0.3 SUVmean, p<0.01). PET/CT and pathology-derived measurements of LV mass, AAR, and infarct size are shown in the Table. Although PET/CT provided accurate quantification of LV mass and the AAR, DE CT significantly overestimated infarct size as measured by post-mortem TTC staining.
Conclusions: A direct comparison of PET/CT imaging and pathology in a porcine model of MI demonstrates that fasting FDG PET provides an accurate estimation of the ischemic AAR 5 days after reperfusion. However, assessment of myocardial salvage with this approach may be confounded by overestimation of infarct size by DE CT at this time point.
Author Disclosures: B.R. Weil: None. G. Techiryan: None. S. Malhotra: None. J.A. Fallavollita: None. J.M. Canty: None.
- © 2016 by American Heart Association, Inc.