title: Grating-based X-ray phase-contrast tomography of atherosclerotic plaque at high photon energies.
abstract: BACKGROUND
  Tissue characterization of atherosclerosis by absorption-based imaging methods is limited due to low soft-tissue contrast. Grating-based phase-contrast computed tomography (PC-CT) may become an alternative for plaque assessment if the phase signal can be retrieved at clinically applicable photon energies. The aims of this feasibility study were (i) to characterize arterial vessels at low and high photon energies, (ii) to extract qualitative features and (iii) quantitative phase-contrast Hounsfield units (HU-phase) of plaque components at 53 keV using histopathology as gold standard.
  
  
  METHODS
  Five human carotid artery specimens underwent grating-based PC-CT using synchrotron radiation of either 23 keV or 53 keV and histological work-up. Specimens without advanced atherosclerosis were used to extract signal criteria of vessel layers. Diseased specimens were screened for important plaque components including fibrous tissue (FT), lipid (LIP), necrotic core (NEC), intraplaque hemorrhage (IPH), inflammatory cell infiltration (INF) and calcifications (CA). Qualitative features as well as quantitative HU-phase were analyzed.
  
  
  RESULTS
  Thirty-three regions in 6 corresponding PC-CT scans and histology sections were identified. Healthy samples had the same signal characteristics at 23 keV and 53 keV with bright tunica intima and adventitia and dark media. Plaque components showed differences in signal intensity and texture at 53 keV. Quantitative analysis demonstrated the highest HU-phase of soft plaque in dense FT. Less organized LIP, NEC and INF were associated with lower HU-phase values. The highest HU-phase were measured in CA.
  
  
  CONCLUSIONS
  PC-CT of atherosclerosis is feasible at high, clinically relevant photon energies and provides detailed information about plaque structure including features of high risk vulnerable plaques.
authors: Institut für Klinische Radiologie, Klinikum der Ludwig-Maximilians-Universität, München, Deutschland. holger.hetterich@med.uni-muenchen.de
authors: Holger
authors: H
authors: Hetterich
authors: Sandra
authors: S
authors: Fill
authors: Julia
authors: J
authors: Herzen
authors: Marian
authors: M
authors: Willner
authors: Irene
authors: I
authors: Zanette
authors: Timm
authors: T
authors: Weitkamp
authors: Alexander
authors: A
authors: Rack
authors: Ulrich
authors: U
authors: Schüller
authors: Mojtaba
authors: M
authors: Sadeghi
authors: Richard
authors: R
authors: Brandl
authors: Silvia
authors: S
authors: Adam-Neumair
authors: Maximilian
authors: M
authors: Reiser
authors: Franz
authors: F
authors: Pfeiffer
authors: Fabian
authors: F
authors: Bamberg
authors: Tobias
authors: T
authors: Saam
mesh_terms: D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D017785:Photons / Q000627:therapeutic use; D011856:Radiographic Image Enhancement / Q000379:methods*; D012031:Refractometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014961:X-Ray Diffraction / Q000379:methods*
keywords: Atherosklerose; Gitter-Interferometrie; Röntgen-basierte Phasenkontrast-Computertomographie; Synchrotron-Strahlung; X-ray-based phase-contrast computed tomography; atherosclerosis; grating-interferometry; synchrotron radiation