title: Enhancement patterns in the fibro cellular tissue in different kinds of plaques of the internal carotid artery.
abstract: BACKGROUND
  The differentiation between stable and vulnerable plaques in the internal carotid artery (ICA) remains a matter of interest. With the implementation of contrast agent in magnetic resonance imaging (MRI) a more detailed plaque characterization is possible. The study at hand focuses on enhancement patterns of fibro cellular tissue in different kinds of plaques in the ICA.
  
  
  METHODS
  Between May 2011 and December 2012, 49 patients (39 male) with >50% stenosis of the ICA were consecutively enrolled. In 10 patients with bilateral ICA stenosis, both plaques were included for analysis. We performed a classification of plaques according to Cai and observed 11 type 4-5 plaques, 15 type 6 plaques and 33 type 8 plaques. MRI was performed on a 3T whole body MR system. The standard 12 channel head coil was combined with the neck extension coil and two bilateral 7 cm loop coils. Post-contrast T1w images were subtracted from pre contrast images to identify late enhancement in fibro cellular tissue. Enhancement patterns were allocated as intraluminal, intraplaque and vasa vasorum enhancement in different types of plaques.
  
  
  RESULTS
  Fibro cellular tissue always exhibited a higher contrast enhancement compared to the sternocleidomastoid muscle. This reflects a higher grade of vascularization of the fibrocellular tissue. Contrast enhancement was present irrespective of the plaque type. In detail, intraluminal, intraplaque and vasa vasorum enhancement were observed in all types of plaques. Even type 8 plaques, according to the classification of Cai, had a significant contrast enhancement, though supposed to be with low inflammatory activity.
  
  
  CONCLUSIONS
  Type 8 plaques might not be as stable as postulated. Whether the relevant uptake of contrast agent is due to the fibrous tissue or reflects the inflammatory activity of the plaque should be matter of further investigations.
authors.affiliation: Department of Vascular Surgery, Innsbruck Medical University, Innsbruck, Austria. Electronic address: barbara.rantner@i-med.ac.at.
authors.forename: Barbara
authors.initials: B
authors.lastname: Rantner
authors.forename: Martin
authors.initials: M
authors.lastname: Sojer
authors.forename: Christian
authors.initials: C
authors.lastname: Kremser
authors.forename: Fabiola
authors.initials: F
authors.lastname: Cartes-Zumelzu
authors.forename: Gustav
authors.initials: G
authors.lastname: Fraedrich
authors.forename: Werner
authors.initials: W
authors.lastname: Jaschke
authors.forename: Iris
authors.initials: I
authors.lastname: Chemelli-Steingruber
mesh_terms: D000368:Aged; D000465:Algorithms; D002343:Carotid Artery, Internal / Q000473:pathology*; D016893:Carotid Stenosis / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Contrast agent; Enhancement patterns; Fibro cellular tissue; Internal carotid artery; MR diagnostics