title: Coronary artery calcium quantification at multi-detector row helical CT versus electron-beam CT.
abstract: OBJECTIVE
  To compare coronary artery calcium scores from a multi-detector row helical computed tomographic (CT) scanner with those from an electron-beam CT scanner, with emphasis on subjects with calcium scores less than 400.
  
  
  METHODS
  Seventy-eight asymptomatic subjects (37 women, 41 men; age range, 39-78 years; mean age, 54.2 years) underwent multi-detector row CT and electron-beam CT. Volume and Agatston scores were calculated with a workstation. Statistical analyses included assessment of association between calcium scores from two scanners, calculation of percent absolute difference to assess score variability between scanners, equivalence analysis, construction of Bland-Altman plots to assess agreement between scores, and assessment of changes in score grouping and risk criteria based on score differences between scanners.
  
  
  RESULTS
  Electron-beam CT calcium scores were higher than multi-detector row CT scores. Linear association between calcium scores obtained from paired scans was significant (r = 0.96-0.99, P <.001). Mean percent absolute differences were 67.9% and 65.0% for volume and Agatston scores, respectively (48.6% and 46.3% for corresponding natural log-transformed scores). In subjects with a score of 11 or greater, mean percent absolute differences between electron-beam CT and multi-detector row CT scores ranged from 15% to 30% (<10% for natural log-transformed calcium scores). With a 20% equivalence limit, calcium scores from the two scanners were statistically equivalent (P <.05). Score grouping would have been subject to change in 12 (11 increased and one decreased; six with scores of 11 or greater), and possible risk management decisions would have been subject to change in eight (16%) of 51 subjects who underwent electron-beam CT versus multi-detector row CT scanning.
  
  
  CONCLUSIONS
  Multi-detector row CT appears to be comparable to electron-beam CT for coronary calcification screening, except in subjects with a calcium score less than 11.
authors.affiliation: Department of Radiology, College of Medicine, University of Iowa, 200 Hawkins Dr, Iowa City, IA 52242, USA. william-stanford@uiowa.edu
authors.forename: William
authors.initials: W
authors.lastname: Stanford
authors.forename: Brad H
authors.initials: BH
authors.lastname: Thompson
authors.forename: Trudy L
authors.initials: TL
authors.lastname: Burns
authors.forename: Scot D
authors.initials: SD
authors.lastname: Heery
authors.forename: Mary C
authors.initials: MC
authors.lastname: Burr
mesh_terms: D000328:Adult; D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging*; D002118:Calcium / Q000032:analysis; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008432:Mathematical Computing; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium