title: Interscan variation in coronary artery calcium quantification in a large asymptomatic patient population.
abstract: OBJECTIVE
  We evaluated interscan variation in coronary artery calcium scores in a large screening population as determined by electron beam CT.
  
  
  METHODS
  One thousand patients (average age, 53 years; age range, 18-85 years) who were asymptomatic for coronary artery disease underwent two consecutive scans of the heart on an electron beam CT scanner. Scans were performed with ECG gating, breath-hold, 3-mm collimation, and 100-msec exposure. Two contiguous pixels with density values greater than 130 H were used as the minimum criterion for a calcific lesion. The calcium score was determined on a vessel-by-vessel basis for both scans of each patient. Interscan variation in calcium and vessels involved with calcification was evaluated on the basis of age, sex, and average calcium score.
  
  
  RESULTS
  The percentage of difference between calcium scores in scans was 28.4% and 43.0% for women and men, respectively. For the individual epicardial arteries (left main, left anterior descending, circumflex, and right coronary), the percentage of difference for calcium scores was 20.2-24.2% for women and 30.5-44.9% for men. A difference between the two scans in at least one vessel of the total coronary arteries identified with calcium was noted in 31% of patients.
  
  
  CONCLUSIONS
  Interscan variability in calcium scores may be important in the determination of risk stratification. Subjects with a nonzero calcium score may benefit from undergoing two scans at the time of initial imaging.
authors.affiliation: Department of Radiology, 1A71 School of Medicine, University of Utah School of Medicine, Salt Lake City 84132, USA.
authors.forename: H C
authors.initials: HC
authors.lastname: Yoon
authors.forename: J G
authors.initials: JG
authors.lastname: Goldin
authors.forename: L E
authors.initials: LE
authors.lastname: Greaser
authors.forename: J
authors.initials: J
authors.lastname: Sayre
authors.forename: G C
authors.initials: GC
authors.lastname: Fonarow
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging*; D002118:Calcium / Q000032:analysis*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D015588:Observer Variation; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D002118:Calcium