title: Coronary artery imaging with single-source rapid kilovolt peak-switching dual-energy CT.
abstract: OBJECTIVE
  To evaluate beam-hardening (BH) artifact reduction in coronary computed tomography (CT) angiography with dual-energy CT, to define the optimal monochromatic-energy levels for coronary and myocardial signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in dual-energy CT, and to compare these levels with single-energy CT.
  
  
  METHODS
  The study was approved by the institutional review board and/or ethics committee at each site. Patients provided informed consent. Thirty-nine patients were prospectively enrolled to undergo dual-energy CT, and 25 also underwent single-energy CT. Myocardial and coronary SNR, CNR, and iodine concentration were measured across multiple segments at varying monochromatic energy levels (40-140 keV). BH was defined as signal decrease in basal inferior wall versus midinferior wall, and signal increase in midseptum versus midinferior wall. Generalized estimating equation was used to identify optimal monochromatic-energy levels and compare them with single-energy CT.
  
  
  RESULTS
  BH was noted at single-energy CT with basal inferior wall mean reduction of 19.7 HU ± 29.2 (standard deviation) and midseptum increase of 46.3 HU ± 36.3. There was reduction in this artifact at 90 keV or greater (1.7 HU ± 18.4 in basal inferior wall and 20.1 HU ± 37.5 in midseptum at 90 keV; P < .05). SNR and CNR were higher in the myocardium and coronary arteries at 60-80 keV than single-energy CT (myocardium: SNR, 3.02 vs 2.39, and CNR, 6.73 vs 5.16; coronary arteries: SNR, 10.83 vs 7.75, and CNR, 13.31 vs 9.54; P < .01). Mean iodine concentration in resting myocardium was 2.19 mg/mL ± 0.57.
  
  
  CONCLUSIONS
  Rapid kilovolt peak-switching dual-energy CT resulted in significant BH reduction and improvements in SNR and CNR in the myocardium and coronary arteries.
authors.affiliation: Department of Medical Imaging, St. Paul's Hospital, 1081 Burrard St, Vancouver, BC, Canada, V6Z 1Y6.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Scheske
authors.forename: Julie M
authors.initials: JM
authors.lastname: O'Brien
authors.forename: James P
authors.initials: JP
authors.lastname: Earls
authors.forename: James K
authors.initials: JK
authors.lastname: Min
authors.forename: Troy M
authors.initials: TM
authors.lastname: LaBounty
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Cury
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
authors.forename: Aaron
authors.initials: A
authors.lastname: So
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Hague
authors.forename: Donya
authors.initials: D
authors.lastname: Al-Hassan
authors.forename: Sachio
authors.initials: S
authors.lastname: Kuriyabashi
authors.forename: David A
authors.initials: DA
authors.lastname: Dowe
authors.forename: Jonathon A
authors.initials: JA
authors.lastname: Leipsic
mesh_terms: D000368:Aged; D000465:Algorithms; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*