Multimodality Imaging of Carotid Artery Plaques

Abstract

Background and Purpose— This study’s objective was to compare 18 F -fluoro-2-deoxyglucose positron emission tomography ( 18 F-FDG PET), CT, and MRI of carotid plaque assessment. Materials and Methods— Fifty patients with symptomatic carotid atherosclerosis underwent 18 F-FDG PET/CT and MRI. Correlations and agreement between imaging findings were assessed by Spearman and Pearson rank correlation tests, t tests, and Bland-Altman plots. Results— Spearman ρ between plaque 18 F-FDG standard uptake values and CT/MRI findings varied from −0.088 to 0.385. Maximum standard uptake value was significantly larger in plaques with intraplaque hemorrhage (1.56 vs 1.47; P =0.032). Standard uptake values did not significantly differ between plaques with an intact and thick fibrous cap and plaques with a thin or ruptured fibrous cap on MRI. (1.21 vs 1.23; P =0.323; and 1.45 vs 1.54; P =0.727). Pearson ρ between CT and MRI measurements varied from 0.554 to 0.794 ( P <0.001). For lipid-rich necrotic core volume, the CT–MRI correlation was stronger in mildly (≤10%) than in severely (>10%) calcified plaques (Pearson ρ 0.730 vs 0.475). Mean difference in measurement ±95% limits of agreement between CT and MRI for minimum lumen area, volumes of vessel wall, lipid-rich necrotic core, calcifications, and fibrous tissue were 0.4±18.1 mm 2 ( P =0.744), −41.9 ±761.7 mm 3 ( P =0.450), 78.4±305.0 mm 3 ( P <0.001), 180.5±625.7 mm 3 ( P =0.001), and −296.0±415.8 mm 3 ( P <0.001), respectively. Conclusions— Overall, correlations between 18 F-FDG PET and CT/MRI findings are weak. Correlations between CT and MRI measurements are moderate to strong, but there is considerable variation in absolute differences.