title: Coronary artery calcium: absolute quantification in nonenhanced and contrast-enhanced multi-detector row CT studies.
abstract: OBJECTIVE
  (a) To determine the accuracy of multi-detector row computed tomography (CT) in the measurement of the calcium concentration in a cardiac CT calibration phantom and (b) to assess the correlation of a traditional 3-mm section width CT coronary screening protocol and a 1.25-mm section width CT angiography imaging protocol in the quantification of the absolute mass of coronary calcium in patients who underwent both coronary screening and CT angiography with a multi-detector row CT scanner.
  
  
  METHODS
  A heart phantom containing calcified cylinders was scanned to determine calibration factors and absolute calcium mass. In 50 patients, the variability (value 1 - value 2/mean value 1 - value 2), limit of agreement (+/-2SD value 1 - value 2), and systematic error (mean value 1 - value 2) of the total amount of coronary calcium calculated at traditional 3-mm section width CT and at 1.25-mm section width CT angiography were determined.
  
  
  RESULTS
  The correlation coefficient between the 3-mm section width, nonenhanced protocol and the 1.25-mm section width CT angiography protocol was very high (r = 0.977) and the mean variability was low (19.7%) for the absolute mass. There was a systematic error of -6.7 mg and a limit of agreement between 45.0 mg and -58.5 mg.
  
  
  CONCLUSIONS
  Use of the mass quantification algorithm in combination with a calibration phantom allows accurate quantification of coronary calcium. Measurements of calcium mass obtained at 1.25-mm section width CT angiography have the best agreement with those obtained at the traditional 3-mm section width imaging protocol.
authors: Department of Clinical Radiology, Klinikum Grosshadern, University of Munich, Marchioninistrasse 15, 81377 Munich, Germany.
authors: Cheng
authors: C
authors: Hong
authors: Christoph R
authors: CR
authors: Becker
authors: U Joseph
authors: UJ
authors: Schoepf
authors: Bernd
authors: B
authors: Ohnesorge
authors: Roland
authors: R
authors: Bruening
authors: Maximilian F
authors: MF
authors: Reiser
mesh_terms: D000465:Algorithms; D000792:Angiography; D002114:Calcinosis / Q000000981:diagnostic imaging*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*