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RESEARCH PRODUCT

016: Evidence of systemic plaque vulnerability in acute coronary syndromes with FDG-positron emission tomography and computed tomographic angiography in the BIOCORE-2 study

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PurposeAtherosclerotic plaque vulnerability is a systemic phenomenon and is often associated with severe plaque infiltration with inflammatory cells. 18-Fluoro-deoxyglucose (FDG) accumulates in inflammatory cells of atherosclerotic plaques. The aim of this study was to assess whether 1) FDG uptake in the aorta and carotid arteries measured by positron emission tomography (PET) is higher in patients with acute coronary syndromes (ACS) than in patients with stable coronary artery disease (CAD) and; 2) associated with morphological markers of plaque instability detected with computed tomography angiography (CTA).MethodsPatients with ACS (n=50) or stable CAD (n=28) underwent a PET 90 minutes after injection of 5MBq/kg FDG followed by a CTA of the thoracic aorta and carotid arteries. Tissue-to-background ratios (TBRs) were calculated by dividing maximal standard uptake value (SUV) of the arterial wall by the mean SUV of blood. A global TBR was calculated in each patient as the average of the TBRs from the thoracic aorta and the 2 carotid arteries. Atherosclerotic plaques were classified with CTA as non-calcified/mixed/calcified, and smooth/irregular.ResultsAortic, carotid and global TBRs (mean±SD) were higher in patients with ACS than in patients with stable CAD (1.78±0.19 vs. 1.61±0.18; 1.84±0.35 vs. 1.64 ±0.17; 1.81±0.23 vs. 1.62±0.16; p<0.05 for all). Patients in the highest quartile of global TBR had a higher percentage of non-calcified and irregular plaques in the thoracic aorta and carotid arteries as compared to patients in the lowest quartile of global TBR (cf. Table 1).ConclusionsFDG uptake in the thoracic aorta and carotid arteries is higher in patients with ACS than in patients with stable CAD and correlates with morphological markers of plaque instability assessed by CTA.Table 1 – Results.Total number of plaquesGlobal TBR valuesPatients with ACSNon calcifiedMixedCalcifiedSmoothIrregularFirst quartile531.36–1.6032%30%45%25%100%0%Second quartile701.61–1.7063%43%37%20%94%6%Third quartile551.71–1.8174%39%47%14%87%13%Forth quartile581.82–2.7585%40%57%3%88%12%