title: Can low-dose CT with iterative reconstruction reduce both the radiation dose and the amount of iodine contrast medium in a dynamic CT study of the liver?
abstract: OBJECTIVE
  To investigate whether low-dose dynamic CT of the liver with iterative reconstruction can reduce both the radiation dose and the amount of contrast medium.
  
  
  METHODS
  This study was approved by our institutional review board. 113 patients were randomly assigned to one of two groups. Group A/group B (fifty-eight/fifty-five patients) underwent liver dynamic CT at 120/100 kV, with 0/40% adaptive statistical iterative reconstruction (ASIR), with a contrast dose of 600/480 mg I/kg, respectively. Radiation exposure was estimated based on the manufacturer's phantom data. The enhancement value of the hepatic parenchyma, vessels and the tumor-to-liver contrast of hepatocellular carcinomas (HCCs) were compared between two groups. Two readers independently assessed the CT images of the hepatic parenchyma and HCCs.
  
  
  RESULTS
  The mean CT dose indices: 6.38/4.04 mGy, the dose-length products: 194.54/124.57 mGy cm, for group A/group B. The mean enhancement value of the hepatic parenchyma and the tumor-to-liver contrast of HCCs with diameters greater than 1cm in the post-contrast all phases did not differ significantly between two groups (P>0.05). The enhancement values of vessels in group B were significantly higher than that in group A in the delayed phases (P<0.05). Two reader's confidence levels for the hepatic parenchyma in the delayed phases and HCCs did not differ significantly between the groups (P>0.05).
  
  
  CONCLUSIONS
  Low-dose dynamic CT with ASIR can reduce both the radiation dose and the amount of contrast medium without image quality degradation, compared to conventional dynamic CT without ASIR.
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okada
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hyodo
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Syojiro
authors.initials: S
authors.lastname: Hidaka
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kagawa
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Matsuki
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan.
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Tsurusaki
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama 589-8511, Japan. Electronic address: murakami@med.kindai.ac.jp.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000150:complications / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage*; D008113:Liver Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; 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*
chemical_list: D003287:Contrast Media; D007455:Iodine
keywords: Contrast medium; Iterative reconstruction; Liver dynamic CT study; Low-dose CT