title: Impact of Knowledge-Based Iterative Model Reconstruction in Abdominal Dynamic CT With Low Tube Voltage and Low Contrast Dose.
abstract: OBJECTIVE
  The purpose of this study was to compare iterative model reconstruction (IMR) and hybrid iterative reconstruction (HIR) of 80-kVp abdominal dynamic CT scans obtained with a low-dose contrast agent.
  
  
  METHODS
  A group of 27 consecutively registered patients underwent abdominal dynamic CT with an 80-kVp protocol and a low dose of contrast agent (300 mg I/kg). Another 27 patients who had previously undergone a 120-kVp protocol with filtered back projection (FBP) and a standard contrast dose (600 mg I/kg) acted as control subjects. Effective dose, image noise, CT number, and contrast-to-noise ratio were compared between the 120-kVp and 80-kVp images with FBP, HIR, and IMR. Image contrast, image noise, image sharpness, noise texture, and overall image quality were evaluated for the four protocols.
  
  
  RESULTS
  The effective dose of the 80-kVp protocol was lower than that with the 120-kVp protocol. The 80-kVp protocol with HIR and IMR decreased image noise by 45% and 70% compared with the 80-kVp protocol with FBP. The contrast-to-noise ratio of the 80-kVp protocol with IMR was higher than that of the 120-kVp protocol. Qualitatively, the 80-kVp protocol with IMR improved image noise more than the 120-kVp protocol did, but noise texture was worse. HIR and the 120-kVp protocol yielded similar subjective image quality.
  
  
  CONCLUSIONS
  Use of the 80-kVp protocol with HIR allowed an approximately 50% reduction in contrast dose and an approximately 40% reduction in radiation dose compared with use of the 120-kVp protocol while preserving image quality. IMR reduced image noise more than HIR with this protocol but worsened noise texture.
authors.affiliation: 1 Department of Diagnostic Radiology, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto 863-0046, Japan.|2 Department of Diagnostic Radiology, Graduate School of Medicine, Kumamoto University, Kumamoto, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Iyama
authors.affiliation: 2 Department of Diagnostic Radiology, Graduate School of Medicine, Kumamoto University, Kumamoto, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.affiliation: 1 Department of Diagnostic Radiology, Amakusa Medical Center, Kameba 854-1, Amakusa, Kumamoto 863-0046, Japan.|2 Department of Diagnostic Radiology, Graduate School of Medicine, Kumamoto University, Kumamoto, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Yokoyama
authors.affiliation: 2 Department of Diagnostic Radiology, Graduate School of Medicine, Kumamoto University, Kumamoto, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.affiliation: 3 Department of Surgery, Amakusa Medical Center, Kumamoto, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Harada
authors.affiliation: 4 Philips Healthcare Asia Pacific, Tokyo, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tokuyasu
authors.affiliation: 2 Department of Diagnostic Radiology, Graduate School of Medicine, Kumamoto University, Kumamoto, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: abdominal dynamic CT; knowledge-based iterative model reconstruction; low tube voltage; low-dose contrast agent