title: Three-dimensional computed tomographic angiography of the liver for planning hepatic surgery: effect of low tube voltage and the iterative reconstruction algorithm on image quality.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of a low tube voltage technique and hybrid iterative reconstruction (HIR) on image quality at 3-dimensional computed tomographic angiography (3D-CTA) of the liver.
  
  
  METHODS
  Before hepatic surgery, we randomly assigned 60 patients (17 women, 43 men; mean ± SD age, 68.9 ± 10.1 years) who had undergone 3D-CTA to 1 of 2 protocols; 30 patients underwent scanning under the conventional 120-kilovolt (peak) protocol with filtered back projection (P1); and 30 patients, under an 80-kilovolt (peak) protocol with HIR (P2). The estimated effective radiation dose, computed tomographic attenuation, image noise, contrast-to-noise ratio, and figure of merit were calculated, and the visual image quality of 3D-CTA was scored on a 4-point scale.
  
  
  RESULTS
  The mean effective radiation dose was significantly lower under P2 than P1 (4.8 ± 1.2 vs 7.2 ± 1.5 mSv, P < 0.01). P1 and P2 did not significantly differ with respect to the image noise (10.5 ± 2.3 vs 9.9 ± 1.6 Hounsfield units; P = 0.46). Computed tomographic attenuation, contrast-to-noise ratio, figure of merit, and the visual scores for image quality were higher under P2 than P1 (P < 0.01).
  
  
  CONCLUSIONS
  The use of low tube voltage and HIR can yield significantly improved image quality at 3D-CTA of the liver.
authors.affiliation: From the *Department of Radiology, Kumamoto Chuo Hospital, Kumamoto, Japan ; †Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan; ‡Department of Surgery, Kumamoto Chuo Hospital, Kumamoto, Japan; and §Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Honda
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Katahira
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kajihara
authors.forename: Shoji
authors.initials: S
authors.lastname: Morishita
authors.forename: Maki
authors.initials: M
authors.lastname: Honbori
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawata
authors.forename: Jiro
authors.initials: J
authors.lastname: Nasu
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000792:Angiography / Q000379:methods*; D003287:Contrast Media; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007472:Iohexol; D007479:Iopamidol; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; D007479:Iopamidol