title: Phase-contrast CT: qualitative and quantitative evaluation of atherosclerotic carotid artery plaque.
abstract: OBJECTIVE
  To evaluate the potential of phase-contrast computed tomography (CT) for atherosclerotic plaque imaging in human carotid arteries in an experimental ex vivo study.
  
  
  METHODS
  The study was approved by the institutional review board, and informed consent was obtained from the patients' relatives. Seven postmortem human carotid artery specimens were imaged at a laboratory setup by using a conventional x-ray tube and grating interferometer. After histologic processing, phase-contrast imaging and histopathologic data were matched. Characteristics of the necrotic core (NC) covered by a fibrous cap (FC), intraplaque hemorrhage (IPH), and calcifications (CAs) were established, and sensitivity, specificity, and accuracy of phase-contrast CT for plaque detection and the potential for accurate quantification were assessed. The Cohen κ and Pearson correlation coefficient R were used to determine the agreement between phase-contrast imaging and histopathologic findings for plaque characterization and correlation of quantitative plaque measurements, respectively. A difference with a P value of less than .05 was considered significant.
  
  
  RESULTS
  Characteristic criteria were found in all analyzed plaque components. Applying these criteria, phase-contrast CT had a good sensitivity for the detection of the FC and NC, IPH, and CAs (all, >80%) and excellent specificity and accuracy (all, >90%), with good interreader agreement (κ ≥ 0.72, P < .0001). There were excellent correlations for quantitative measurements of FC, NC, and CAs between phase-contrast imaging and histopathologic findings (R ≥ 0.92). Interreader reproducibility was excellent, with an intraclass correlation coefficient of 0.98 or higher for all measurements.
  
  
  CONCLUSIONS
  The results of this study indicate that ex vivo phase-contrast CT can help identify and quantify atherosclerotic plaque components, with excellent correlation to histopathologic findings. Although not yet applicable in vivo, phase-contrast CT may become a valuable tool to monitor atherosclerotic disease process noninvasively.
authors.affiliation: From the Institute of Clinical Radiology (H.H., S.F., F.B., S.A., S.W., M.R., T.S.), Center for Neuropathology (U.S.), and Institute of Anatomy (S.A.), Ludwig-Maximilians-University Hospital, Pettenkoferstrasse 8a, 80336 Munich, Germany; {Department of Physics and Institute for Technical Medicine}, Technische Universität München, Garching, Germany (M.W., J.H., A.H., F.P.); and Institute of Materials Research, Helmholtz-Zentrum, Geesthacht, Germany (J.H.).
authors.forename: Holger
authors.initials: H
authors.lastname: Hetterich
authors.forename: Marian
authors.initials: M
authors.lastname: Willner
authors.forename: Sandra
authors.initials: S
authors.lastname: Fill
authors.forename: Julia
authors.initials: J
authors.lastname: Herzen
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.forename: Alexander
authors.initials: A
authors.lastname: Hipp
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schüller
authors.forename: Silvia
authors.initials: S
authors.lastname: Adam-Neumair
authors.forename: Stefan
authors.initials: S
authors.lastname: Wirth
authors.forename: Maximilian
authors.initials: M
authors.lastname: Reiser
authors.forename: Franz
authors.initials: F
authors.lastname: Pfeiffer
authors.forename: Tobias
authors.initials: T
authors.lastname: Saam
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*