title: Coronary calcium scoring using 16-row multislice computed tomography: nonenhanced versus contrast-enhanced studies in vitro and in vivo.
abstract: OBJECTIVE
  We sought to assess the agreement of coronary artery calcium score in nonenhanced and contrast-enhanced multislice-spiral computed tomography.
  
  
  METHODS
  Vessel phantoms and 36 patients underwent nonenhanced and contrast-enhanced cardiac multislice-spiral computed tomography (Sensation 16; Siemens, Germany). Reconstruction-parameters: slice thickness 3 mm, increment 2 mm, kernels B35f and B30f. The Agatston score, calcium mass, and number of lesions were calculated. Images were scored using detection thresholds of 130 Hounsfield units (HU) and 350 HU. Based on the Agatston score, risk stratification was performed.
  
  
  RESULTS
  In the phantom and patient study, altering the threshold from 130 to 350 HU led to a significant decrease in the mean Agatston score (phantom: 54.6%, patients: 66.7%) and calcium mass (33.0%, 47.0%) (B35f). Contrast-enhanced studies (threshold: 350 HU) showed an increase of the mean Agatston score (71.0%, 20.7%) and calcium mass (81.0%, 16.0%) when compared with nonenhanced scans (threshold: 350 HU). A total of 57% of all patients were assigned to different risk groups.
  
  
  CONCLUSIONS
  Contrast material may simulate calcification; therefore, calculation of the coronary calcium score from contrast-enhanced images is not reliable.
authors.affiliation: Department of Diagnostic Radiology, University Hospital (RWTH) Aachen, Germany. gmuehlen@rad.rwth-aachen.de
authors.forename: Georg
authors.initials: G
authors.lastname: Mühlenbruch
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
authors.forename: Ralf
authors.initials: R
authors.lastname: Koos
authors.forename: Marco
authors.initials: M
authors.lastname: Das
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Flohr
authors.forename: Matthias
authors.initials: M
authors.lastname: Niethammer
authors.forename: Claudia
authors.initials: C
authors.lastname: Weiss
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Günther
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
mesh_terms: D002114:Calcinosis / Q000000981:diagnostic imaging*; D002118:Calcium / Q000032:analysis; D002138:Calibration; D009202:Cardiomyopathies / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D036542:Tomography, Spiral Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide; D002118:Calcium