title: Non-invasive imaging of atherosclerotic plaque macrophage in a rabbit model with F-18 FDG PET: a histopathological correlation.
abstract: BACKGROUND
  Coronary atherosclerosis and its thrombotic complications are the major cause of mortality and morbidity throughout the industrialized world. Thrombosis on disrupted atherosclerotic plaques plays a key role in the onset of acute coronary syndromes. Macrophages density is one of the most critical compositions of plaque in both plaque vulnerability and thrombogenicity upon rupture. It has been shown that macrophages have a high uptake of 18F-FDG (FDG). We studied the correlation of FDG uptake with histopathological macrophage accumulation in atherosclerotic plaques in a rabbit model.
  
  
  METHODS
  Atherosclerosis was induced in rabbits (n = 6) by a combination of atherogenic diet and balloon denudation of the aorta. PET imaging was performed at baseline and 2 months after atherogenic diet and coregistered with magnetic resonance (MR) imaging. Normal (n = 3) rabbits served as controls. FDG uptake by the thoracic aorta was expressed as concentration (muCi/ml) and the ratio of aortic uptake-to-blood radioactivity. FDG uptake and RAM-11 antibody positive areas were analyzed in descending aorta.
  
  
  RESULTS
  Atherosclerotic aortas showed significantly higher uptake of FDG than normal aortas. The correlation of aortic FDG uptake with macrophage areas assessed by histopathology was statistically significant although it was not high (r = 0.48, p < 0.0001). When uptake was expressed as the ratio of aortic uptake-to-blood activity, it correlated better (r = 0.80, p < 0.0001) with the macrophage areas, due to the correction for residual blood FDG activity.
  
  
  CONCLUSIONS
  PET FDG activity correlated with macrophage content within aortic atherosclerosis. This imaging approach might serve as a useful non-invasive imaging technique and potentially permit monitoring of relative changes in inflammation within the atherosclerotic lesion.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, The Mount Sinai School of Medicine, New York, NY, USA. zhuangyu.zhang@mssm.edu
authors.forename: Zhuangyu
authors.initials: Z
authors.lastname: Zhang
authors.forename: Josef
authors.initials: J
authors.lastname: Machac
authors.forename: Gerard
authors.initials: G
authors.lastname: Helft
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Worthley
authors.forename: Cheuk
authors.initials: C
authors.lastname: Tang
authors.forename: Azfar G
authors.initials: AG
authors.lastname: Zaman
authors.forename: Oswaldo J
authors.initials: OJ
authors.lastname: Rodriguez
authors.forename: Monte S
authors.initials: MS
authors.lastname: Buchsbaum
authors.forename: Valentin
authors.initials: V
authors.lastname: Fuster
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Badimon