title: The Influence of Iterative Reconstruction on Coronary Artery Calcium Scoring-Phantom and Clinical Studies.
abstract: We compared the effect of iterative model reconstruction (IMR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) scoring.
  
  
  
  CAC scans of 30 consecutive patients (18 men and 12 women, age 70.1 ± 12.2 years) were reconstructed with FBP, HIR, and IMR, and the image noise was measured on all images. Two radiologists independently measured the CAC scores using semiautomated software, and interobserver agreement was evaluated. Statistical analysis included the Spearman correlation coefficient and Bland-Altman analysis.
  
  
  
  The mean image noise on FBP, HIR, and IMR images was 48.0 ± 7.9, 29.6 ± 4.8, and 9.3 ± 1.3 Hounsfield units, respectively. The difference among all reconstruction combinations was significant (P < .01). The CAC score on HIR and IMR scans was 4.2% and 8.9% lower, respectively, than the CAC score on FBP images. There was no significant difference in the mean CAC score among the three reconstructions. The interobserver correlation was excellent for all three reconstructions (r2= 0.96 FBP, 0.99 HIR, 0.99 IMR); the best Bland-Altman measure of agreement was with IMR, followed by HIR and FBP.
  
  
  
  For CAC scoring, IMR can reduce the image noise and blooming artifacts, and consequently lowers the measured CAC score. IMR can lessen measurement variability and yield stable, reproducible measurements.
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan. Electronic address: seisei0430@nifty.com.
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.affiliation: Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yuki
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Hirata
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Narumi
authors.initials: N
authors.lastname: Taguchi
authors.affiliation: Department of Diagnostic Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Honda
authors.affiliation: Department of Diagnostic Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takaoka
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Iyama
authors.affiliation: Department of Diagnostic Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Katahira
authors.affiliation: Department of Cardiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors.forename: Katsuo
authors.initials: K
authors.lastname: Noda
authors.affiliation: Department of Cardiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Oshima
authors.affiliation: CT Clinical Science, Philips Electronics Japan, Tokyo, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tokuyasu
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D016477:Artifacts; D002114:Calcinosis / Q000150:complications / Q000000981:diagnostic imaging*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Agatston score; Iterative reconstruction; coronary artery calcium; image quality; measurement variability