Abstract WP151: 18 F-FDG Uptake Identify Vulnerable Carotid Plaque on PET/CT in a Swine Model

Abstract

Purpose: The imaging modality 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography (PET) has been recently used to identify inflammation in the atherosclerotic plaque. Increased uptake of 18 F-FDG in human atherosclerotic plaque on PET may predict plaque vulnerability, however, there is a lack of histological validation for PET imaging. The aim of this study is to evaluate the association of plaque vulnerability with FDG uptake on serial PET/CT scans in a swine model. Methods: Twenty carotid atherosclerotic models was induced in 10 miniswines using partial ligation and high cholesterol diet, and a minimum 70% stenosis was confirmed by carotid angiography. Serial 18 F-FDG PET/CT scans were performed at 0, 4, 8 and 12 weeks. MR scan for imaging-histologic correlation was performed at 12 weeks, and carotid artery sections were obtained for histopathological examination. The atherosclerotic lesions of AHA type IV to VI were defined as advanced plaques. Carotid arteries were evaluated for increased FDG uptake with a maximum standardized uptake value (SUV) and target-to-backgroud ratio (TBR). The association of carotid plaque vulerability with the serial FDG uptake was analyzed. Results: Various stages of atherosclerotic plaques were found in carotid segments from 20 carotid arteries. Most advanced plaque had the feature of vulnerability. FDG uptake in 100 carotid plaques were analyzed. Compared with carotid segments without atherosclerosis, significantly higher FDG uptake was observed in carotid segments with atherosclerosis at 4, 8 and 12 weeks (P<0.001). Mean TBR was significantly higher in advanced plaque group than in early atherosclerosis group at 4, 8 and 12 weeks (P<0.01). Maximum SUV was significantly higher in advanced plaque group than in early atherosclerosis group at 12 weeks (P<0.01), whereas this did not reach statistical significance at 4 and 8 weeks. FDG uptake increased continuously in both groups of advance plaque and early atherosclerosis. Conclusion: Increased plaque metabolism revealed by PET persists with time and is associated with the complexity of carotid atherosclerotic plaque in a swine model. FDG PET/CT may be useful for identification of plaque vulnerability and monitoring the progress of atherosclerotic lesions.