title: Dual energy computed tomography quantification of carotid plaques calcification: comparison between monochromatic and polychromatic energies with pathology correlation.
abstract: OBJECTIVE
  We compared carotid plaque calcification detection sensitivity and apparent cross-sectional area on CT as a function of CT beam energy using conventional CT techniques and virtual mono-energetic CT images generated from dual-energy acquisitions.
  
  
  METHODS
  Five ex-vivo carotid endarterectomy (CEA) specimens were imaged with dual-energy computed tomography. Virtual monochromatic spectrum (VMS) CT images were reconstructed at energies between 40-140 keV. The same specimens were imaged using conventional polyenergetic spectrum (PS) CT with peak beam energies 80, 100, 120, and 140 kVp. The histological calcium areas on each corresponding CEA specimen were traced manually on digitized images of Toluidine-Blue/Basic-Fuchsin stained plastic sections.
  
  
  RESULTS
  40 keV VMS CT images provided high detection sensitivity (97 %) similar to conventional PS CT images (~96 %). The calcification size measured on CT decreased systematically with increasing CT beam energy; the rate of change was larger for the VMS images than for PS images.
  
  
  CONCLUSIONS
  From a single dual-energy CT, multiple VMS-CT images can be generated, yielding equivalent detection sensitivity and size correlations as conventional PS-CT in CEA calcification imaging. VMS-CT at 80-100 keV provided the most accurate estimates of calcification size, as compared to histology, but detection sensitivity was reduced for smaller calcifications on these images.
  
  
  CONCLUSIONS
  • Calcifications depicted at 80-100 keV were most similar to the histology standard. • Conventional polychromatic images demonstrated excellent correlation with plaque size at pathology. • Conventional polychromatic images systematically overestimate plaque size. • Plaque calcifications can be missed on high energy monochromatic images.
authors.affiliation: Departments of Radiology, University of Washington, Seattle, WA, USA, mannellilorenzo@yahoo.it.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Mannelli
authors.forename: Lawrence
authors.initials: L
authors.lastname: MacDonald
authors.forename: Marcello
authors.initials: M
authors.lastname: Mancini
authors.forename: Marina
authors.initials: M
authors.lastname: Ferguson
authors.forename: William P
authors.initials: WP
authors.lastname: Shuman
authors.forename: Monica
authors.initials: M
authors.lastname: Ragucci
authors.forename: Serena
authors.initials: S
authors.lastname: Monti
authors.forename: Dongxiang
authors.initials: D
authors.lastname: Xu
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
authors.forename: Lee M
authors.initials: LM
authors.lastname: Mitsumori
mesh_terms: D004210:Dissection; D016894:Endarterectomy, Carotid; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*