title: Technical feasibility and validation of a coronary artery calcium scoring system using CT coronary angiography images.
abstract: OBJECTIVE
  We validate a novel CT coronary angiography (CCTA) coronary calcium scoring system.
  
  
  METHODS
  Calcium was quantified on CCTA images using a new patient-specific attenuation threshold: mean + 2SD of intra-coronary contrast density (HU). Using 335 patient data sets a conversion factor (CF) for predicting CACS from CCTA scores (CCTAS) was derived and validated in a separate cohort (n = 168). Bland-Altman analysis and weighted kappa for MESA centiles and Agatston risk groupings were calculated.
  
  
  RESULTS
  Multivariable linear regression yielded a CF: CACS = (1.185 × CCTAS) + (0.002 × CCTAS × attenuation threshold). When applied to CCTA data sets there was excellent correlation (r = 0.95; p < 0.0001) and agreement (mean difference -10.4 [95% limits of agreement -258.9 to 238.1]) with traditional calcium scores. Agreement was better for calcium scores below 500; however, MESA percentile agreement was better for high risk patients. Risk stratification was excellent (Agatston groups k = 0.88 and MESA centiles k = 0.91). Eliminating the dedicated CACS scan decreased patient radiation exposure by approximately one-third.
  
  
  CONCLUSIONS
  CCTA calcium scores can accurately predict CACS using a simple, individualized, semiautomated approach reducing acquisition time and radiation exposure when evaluating patients for CAD. This method is not affected by the ROI location, imaging protocol, or tube voltage strengthening its clinical applicability.
  
  
  CONCLUSIONS
  • Coronary calcium scores can be reliably determined on contrast-enhanced cardiac CT • This score can accurately risk stratify patients • Elimination of a dedicated calcium scan reduces patient radiation by a third.
authors.affiliation: Department of Cardiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.|Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Pavitt
authors.affiliation: Centre for Paediatric Epidemiology and Biostatistics, Institute of Child Health, UCL, London, WC1N 1EH, UK.
authors.forename: Katie
authors.initials: K
authors.lastname: Harron
authors.affiliation: Department of Cardiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Alistair C
authors.initials: AC
authors.lastname: Lindsay
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Sayeh
authors.initials: S
authors.lastname: Zielke
authors.affiliation: Department of Cardiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Ray
authors.affiliation: Department of Physics, Royal Marsden Hospital, Fulham Rd, London, SW3 6JJ, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gordon
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Rubens
authors.affiliation: Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK.|Faculty of Medicine, Imperial College, London, SW7 2AZ, UK.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Padley
authors.affiliation: Department of Cardiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. e.nicol@rbht.nhs.uk.|Department of Radiology, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, UK. e.nicol@rbht.nhs.uk.|Faculty of Medicine, Imperial College, London, SW7 2AZ, UK. e.nicol@rbht.nhs.uk.
authors.forename: Edward D
authors.initials: ED
authors.lastname: Nicol
mesh_terms: D000368:Aged; D017023:Coronary Angiography / Q000379:methods; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D061330:Multidetector Computed Tomography / Q000379:methods; D015588:Observer Variation; D011829:Radiation Dosage; D015203:Reproducibility of Results; D061205:Vascular Calcification / Q000000981:diagnostic imaging*
keywords: Agatston score; CT coronary angiography; Calcium scoring; Cardiac CT; Cardiovascular risk