title: Coronary artery calcium scoring on low-dose prospective electrocardiographically-triggered 64-slice CT.
abstract: OBJECTIVE
  The purpose of this prospective study was to assess image noise and variability in repeated coronary artery calcium (CAC) scoring on low-dose prospective electrocardiographically-triggered 64-slice multidetector computed tomography.
  
  
  METHODS
  Patients (n = 115) suspected of having coronary artery disease were scanned twice, using a tube current of 10 x body mass index mA. The standard deviation (SD) of the computed tomographic value in the ascending aorta and (mean + 2 x SD) were obtained. Repeated CAC scores (Agatston, volume, and mass) were measured by two observers, and the interscan and interobserver variability were determined.
  
  
  RESULTS
  The mean tube current used was 246 +/- 36 mA. The mean tube current-time product and mean estimated effective dose were 57 +/- 8 mA and 0.9 +/- 0.2 mSv, respectively. The SD and (mean + 2 x SD) computed tomographic values in the ascending aorta were 16 +/- 3 and 75 +/- 10 Hounsfield units, respectively. Repeated CAC scores were correlated (r(2) = 0.995-0.998). The interscan variability for observer 1 and observer 2, respectively, were 13% and 13% for Agatston score, 12% and 11% for volume, and 11% and 11% for mass. The interobserver variability for scan 1 and scan 2, respectively, were 3% and 3% for Agatston score, 5% and 3% for volume, and 3% and 3% for mass.
  
  
  CONCLUSIONS
  Low-dose prospective electrocardiographically-triggered 64-slice multidetector computed tomography shows low interscan and interobserver variability on CAC scoring while maintaining low image noise.
authors.affiliation: Department of Clinical Radiology, Hiroshima University Hospital, Hiroshima, Japan. horiguch@hiroshima-u.ac.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Horiguchi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Matsuura
authors.forename: Hideya
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Masao
authors.initials: M
authors.lastname: Kiguchi
authors.forename: Chikako
authors.initials: C
authors.lastname: Fujioka
authors.forename: Toshiro
authors.initials: T
authors.lastname: Kitagawa
authors.forename: Nobuoki
authors.initials: N
authors.lastname: Kohno
authors.forename: Katsuhide
authors.initials: K
authors.lastname: Ito
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*