title: Electron beam CT versus 16-MDCT on the variability of repeated coronary artery calcium measurements in a variable heart rate phantom.
abstract: OBJECTIVE
  High reproducibility of coronary artery calcium (CAC) scoring is a key requirement for monitoring the progression of coronary atherosclerosis. The purposes of this study were to compare electron beam CT and 16-MDCT scanners in the variability of repeated CAC measurements and to assess the factors influencing this variability.
  
  
  METHODS
  CAC models of different sizes attached to a cardiac phantom with a programmable variable heart rate were scanned three times, and interscan variability of the CAC measurement was calculated each time. For helical CT, different slice-thickness images of either retrospective ECG-gated or prospective ECG-triggering reconstruction were obtained. The detection of small amounts of calcium, variability of the Agatston score, and CAC measurement algorithms (Agatston, volume, and mass scores) were compared between CT scanners and protocols.
  
  
  RESULTS
  All 1-mm-sized calcium models were detected on 0.625- and 1.25-mm helical CT, whereas some were missed on electron beam CT and 2.5-mm helical CT. Retrospective ECG-gated thin-slice helical CT showed the lowest variability. Reduction of variability by volume and mass scoring algorithms was less effective on 0.625- and 1.25-mm-thickness CT.
  
  
  CONCLUSIONS
  Retrospective ECG-gated thin-slice helical CT has the potential to be a useful tool for monitoring coronary atherosclerosis.
authors.affiliation: Department of Clinical Radiology, Hiroshima University Hospital, 1-2-3, Kasumi-cho, Minami-ku, Hiroshima 734-8551, Japan. horiguch@hiroshima-u.ac.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Horiguchi
authors.forename: Yun
authors.initials: Y
authors.lastname: Shen
authors.forename: Yuji
authors.initials: Y
authors.lastname: Akiyama
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hirai
authors.forename: Kousuke
authors.initials: K
authors.lastname: Sasaki
authors.forename: Minoru
authors.initials: M
authors.lastname: Ishifuro
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Katsuhide
authors.initials: K
authors.lastname: Ito
mesh_terms: D000465:Algorithms; D002114:Calcinosis / Q000000981:diagnostic imaging*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D015898:Tomography Scanners, X-Ray Computed; D036542:Tomography, Spiral Computed