Combined application of 18F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging in early diagnosis of vulnerable carotid atherosclerotic plaques.

OBJECTIVE: To assess the correlations between atherosclerotic plaque characteristics and inflammatory activity by combined use of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI).
METHODS: Patients underwent (18)F-FDG PET/CT and MRI. Target/background ratios (TBR) of axial sections were determined from mean standard uptake values (SUV). Correlations between TBR and mean vessel wall thickness, total vessel area, lumen area, vessel wall area and normalized wall index were calculated. Plaque types were defined as calcified, collagen, lipid or haemorrhage. Plaques were also classified as thick, thin, or ruptured fibrous cap.
RESULTS: The study included 31 patients (1178 plaque slices). There was a significant decrease in TBR values across the fibrous cap groups, such that ruptured > thin > thick. Lipid and haemorrhage plaques had significantly higher TBR than calcification and collagen plaques. There were weak positive correlations between TBR and mean vessel wall thickness, vessel wall area and normalized wall index.
CONCLUSIONS: Thin or ruptured plaques, lipid-rich plaques and haemorrhagic plaques possess high inflammatory activity. The combination of (18)F-FDG PET/CT and MRI could be useful for qualitative and quantitative diagnosis of carotid atherosclerotic plaques.