title: Analyzer-based phase-contrast x-ray imaging of carotid plaque microstructure.
abstract: BACKGROUND
  Plaque vulnerability depends, in part, on composition. Imaging techniques are needed that can aid the prediction of plaque stability. High-contrast images of soft-tissue structure have been obtained with x-ray phase-contrast (PC) imaging. This research investigates multiple image radiography (MIR), an x-ray PC imaging technique, for evaluation of human carotid artery plaques.
  
  
  METHODS
  Carotid plaques were imaged with ultrasound and subsequently excised and formalin fixed. MIR imaging was performed. By using synchrotron radiation, conventional radiographs were acquired for comparison. Image texture measures were computed for soft-tissue regions of the plaques.
  
  
  RESULTS
  Ultrasound evaluation identified plaques as homogeneous without calcifications. MIR images revealed complex heterogeneous structure with multiple microcalcifications consistent with histology, and possessed more image texture in specific regions than conventional radiographs (P < .05). MIR refraction images allowed imaging of the geometric structure of tissue interfaces within the plaques, while scatter images contained more texture in soft-tissue regions than absorption or refraction images.
  
  
  CONCLUSIONS
  X-ray PC imaging better depicts plaque soft-tissue heterogeneity than ultrasound or conventional radiographs. MIR imaging technique should be investigated further as a viable imaging technique to identify high-risk plaques.
authors.affiliation: Department of Research, Hines VA Hospital, Hines, IL 60616-3793, USA.
authors.forename: Alyssa A
authors.initials: AA
authors.lastname: Appel
authors.forename: Cheng-Ying
authors.initials: CY
authors.lastname: Chou
authors.forename: Howard P
authors.initials: HP
authors.lastname: Greisler
authors.forename: Jeffery C
authors.initials: JC
authors.lastname: Larson
authors.forename: Sunil
authors.initials: S
authors.lastname: Vasireddi
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhong
authors.forename: Mark A
authors.initials: MA
authors.lastname: Anastasio
authors.forename: Eric M
authors.initials: EM
authors.lastname: Brey
mesh_terms: D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D066298:In Vitro Techniques; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography