Complementarity between F-18-FDG PET/CT and Ultrasonography or Angiography in Carotid Plaque Characterization

Abstract

Background and Purpose To estimate clinical roles of F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) versus angiography and ultrasonography in carotid plaque characterization. Methods We characterized two groups of patients with recently (<1 month) symptomatic (n=14; age=71.8 +/- 8.6 years, mean +/- SD) or chronic (n=13, age=68.9 +/- 9.0 years) carotid stenosis using a battery of imaging tests: diffusion magnetic resonance (MR) imaging, MR or transfemoral angiography, duplex ultrasonography (DUS), and carotid FDG-PET/computed tomography. Results The degree of angiographic stenosis was greater in patients with recently symptomatic carotid plaques (67.5 +/- 21.5%) than in patients with chronic carotid plaques (32.4 +/- 26.8%, p=0.001). Despite the significant difference in the degree of stenosis, lesional maximum standardized uptake values (maxSUVs) on the carotid FDG-PET did not differ between the recently symptomatic (1.56 +/- 0.53) and chronic (1.56 +/- 0.34,p=0.65) stenosis groups. However, lesional-to-contralesional maxSUV ratios were higher in the recently symptomatic stenosis group (113 +/- 17%) than in the chronic stenosis group (98 +/- 10%, p=0.017). The grayscale median value of the lesional DUS echodensities was lower in the recently symptomatic stenosis group (28.2 +/- 10.0, n=9) than in the chronic stenosis group (53.9 +/- 14.0, n=8; p=0.001). Overall, there were no significant correlations between angiographic stenosis, DUS echodensity, and FDG-PET maxSUV. Case/subgroup analyses suggested complementarity between imaging modalities. Conclusions There were both correspondences and discrepancies between the carotid FDG-PET images and DUS or angiography data. Further studies are required to determine whether FDG-PET could improve the clinical management of carotid stenosis.