Abstract 13422: Molecular Imaging of Vascular and Myocardial 18F-FDG Uptake with PET/CT in Patients Early After an Acute Coronary Syndrome
Objectives: The study tested the hypothesis that the metabolic signal caused by activated macrophages allows the localization of the culprit lesion early after an acute coronary syndrome (ACS) by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT). Background: Inflammation is a key feature of vulnerable plaques, which are at high risk of rupture. Vascular inflammation can be measured noninvasively by 18F-FDG-PET.
Methods: 21 patients (pts, mean age 63±13 years, 57% males) presenting with ACS (76% myocardial infarctions, 24% troponin-positive unstable angina) were studied with a hybrid imaging protocol (13-N-NH3 for perfusion and 18-F-FDG for inflammation assessment combined with a high resolution CT) early after percutaneous coronary intervention and stent implantation (7+/−4 days). A low-carbohydrate, high-fat diet the day before the study was used to suppress the normal myocardial FDG uptake. CT based vessel tracking of the proximal coronary segments including all culprit lesions allowed the automatic quantification of FDG uptake along the tracked coronaries. Finally, blood FDG uptake from the left ventricular cavity was used to calculate vessel uptake ratios (VBR). VBR values of vessels supplying remote myocardium were used to delineate normal values.
Results: Normal VBR values were 1.3+/−0.13. Using a threshold of 2 standard deviations, four patients (19%) showed enhanced coronary FDG uptake (2.1±0.3). None of these pts were on statins before the ACS, all had significant CRP elevations (38.2±42.4 mg/dl), three were newly diagnosed with coronary artery disease, three had ST-segment elevation MIs with high maximum creatinine kinase concentrations (2885.0+/−1830.7 U/L) and all had culprit coronary lesions that had to be recanalized because of an acute thrombotic occlusion.
Conclusions: The incidence of locally increased FDG uptake was relatively low in our prospective study of pts with ACS. This may be explained by limited sensitivity of low resolution vascular imaging by PET, but may also be the result of aggressive anti-inflammatory therapy including drug eluting stents. FDG positive lesions may identify a subgroup of pts with a pronounced inflammatory phenotype of ACS as documented by high CRP.
- © 2010 by American Heart Association, Inc.