title: A knowledge-based iterative model reconstruction algorithm: can super-low-dose cardiac CT be applicable in clinical settings?
abstract: OBJECTIVE
  To investigate whether "full" iterative reconstruction, a knowledge-based iterative model reconstruction (IMR), enables radiation dose reduction by 80% at cardiac computed tomography (CT).
  
  
  METHODS
  A total of 23 patients (15 men, eight women; mean age 64.3 ± 13.4 years) who underwent retrospectively electrocardiography-gated cardiac CT with dose modulation were evaluated. We compared full-dose (FD; 730 mAs) images reconstructed with filtered back projection (FBP) technique and the low-dose (LD; 146 mAs) images reconstructed with FBP and IMR techniques. Objective and subjective image quality parameters were compared among the three different CT images.
  
  
  RESULTS
  There was no significant difference in the CT attenuation among the three reconstructions. The mean image noise of LD-IMR (18.3 ± 10.6 Hounsfield units [HU]) was significantly lowest among the three reconstructions (41.9 ± 15.3 HU for FD-FBP and 109.9 ± 42.6 HU for LD-FBP; P < .01). The contrast-to-noise ratio of LD-IMR was better than that of FD-FBP and LD-FBP (P < .01). Visual evaluation score was also highest for LD-IMR.
  
  
  CONCLUSIONS
  The IMR can provide improved image quality at super-low-dose cardiac CT with 20% of the standard tube current.
authors: 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: Seitaro
authors: S
authors: Oda
authors: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors: Daisuke
authors: D
authors: Utsunomiya
authors: Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors: Yoshinori
authors: Y
authors: Funama
authors: Department of Diagnostic Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors: Kazuhiro
authors: K
authors: Katahira
authors: Department of Diagnostic Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors: Keiichi
authors: K
authors: Honda
authors: CT Clinical Science, Philips Electronics Japan, Minato-ku, Tokyo, Japan.
authors: Shinichi
authors: S
authors: Tokuyasu
authors: CT Clinical Science, Philips Healthcare, Cleveland, OH.
authors: Mani
authors: M
authors: Vembar
authors: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors: Hideaki
authors: H
authors: Yuki
authors: Department of Cardiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors: Katsuo
authors: K
authors: Noda
authors: Department of Cardiology, Kumamoto Chuo Hospital, Kumamoto, Japan.
authors: Shuichi
authors: S
authors: Oshima
authors: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Chuo-ku, Kumamoto, 860-8556, Japan.
authors: Yasuyuki
authors: Y
authors: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001185:Artificial Intelligence; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: Cardiac CT; image quality; iterative reconstruction; radiation dose