title: Feasibility of coronary artery calcium scoring on virtual unenhanced images derived from single-source fast kVp-switching dual-energy coronary CT angiography.
abstract: BACKGROUND
  Dual-energy CT technology enables acquisition of virtual unenhanced (VUE) images from contrast-enhanced scans.
  
  
  OBJECTIVE
  To assess the feasibility of coronary artery calcium (CAC) scoring on VUE images derived from fast kVp-switching dual-energy coronary CT angiography.
  
  
  METHODS
  Twenty-seven patients underwent true noncontrast CAC-scoring CT followed by routine single-energy (120-kVp) and fast kVp-switching dual-energy coronary CT angiography, in a random acquisition order on the same day. We calculated the CAC scores on true noncontrast and VUE images. The image noises and the signal-to-noise and contrast-to-noise ratios of the aorta and coronary arteries were measured on both the single-energy coronary CT angiography images and dual-energy coronary CT angiography images (70 keV virtual monochromatic spectral images). The Pearson correlation coefficient test and paired t test were used for statistical analysis.
  
  
  RESULTS
  Excellent correlation was observed between the CAC scores on the true noncontrast and those on the VUE images (r = 0.88; P < .001). Compared with single-energy coronary CT angiography, dual-energy coronary CT angiography showed significantly reduced image noise and increased signal-to-noise and contrast-to-noise ratios in all regions (all P < .001). The effective dose of dual-energy coronary CT angiography (4.3 ± 0.3 mSv) was significantly lower than that of true noncontrast CAC-scoring CT plus single-energy coronary CT angiography (5.4 ± 0.7 mSv; P < .0001).
  
  
  CONCLUSIONS
  Excellent correlation was observed between the CAC scores on the VUE images and true noncontrast images. Thus, fast kVp-switching dual-energy coronary CT angiography could allow prediction of the true CAC scores, potentially reducing the total radiation exposure and image acquisition time by obviating the need for true noncontrast CAC-scoring CT.
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Yamada
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. Electronic address: jinzaki@rad.med.keio.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Jinzaki
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Teppei
authors.initials: T
authors.lastname: Okamura
authors.affiliation: Multi-dimension Biomedical Imaging and Information Laboratory in Research Park, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yamada
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tanami
authors.affiliation: Department of Preventive Medicine and Public Health, Center for Clinical Research, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Abe
authors.affiliation: Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Sachio
authors.initials: S
authors.lastname: Kuribayashi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002114:Calcinosis / Q000150:complications / Q000000981:diagnostic imaging*; D002118:Calcium / Q000032:analysis; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000209:etiology; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; 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*; D014584:User-Computer Interface
chemical_list: D003287:Contrast Media; D002118:Calcium
keywords: Contrast media; Coronary artery disease; Multidetector computed tomography; Radiation dosage; Signal-to-noise ratio