title: Reducing iodine load in hepatic CT for patients with chronic liver disease with a combination of low-tube-voltage and adaptive statistical iterative reconstruction.
abstract: OBJECTIVE
  To prospectively assess the effect of reduced iodine load to contrast enhancement, image quality, and detectability of hepatocellular carcinomas (HCCs) in hepatic CT with a combination of 80 kVp tube voltage setting and adaptive statistical iterative reconstruction (ASIR) technique in patients with chronic liver disease.
  
  
  METHODS
  This HIPAA-compliant study was approved by our institutional review board and written informed consent was obtained in all patients. During a recent 9-month period, 170 consecutive patients (114 men and 56 women; age range, 40-85 years; mean, 67.7 years) with suspected chronic liver diseases were randomized into three CT groups according to the following iodine-load and tube-voltage protocols: 600 milligram per kilogram body weight (mg/kg) iodine load and 120 peak kilovolt (kVp) tube voltage setting (600-120 group), 500 mg/kg and 80 kVp (500-80 group), and 400mg/kg and 80 kVp (400-80 group). Analysis of variance was conducted to evaluate differences in CT number, background noise, signal-to-noise ratio (SNR), effective dose, HCC-to-liver contrast-to-noise ratio (CNR), and figure of merit (FOM). Sensitivity, specificity, and area under the receiver-operating-characteristic curve (AUC) were compared to assess the detectability of HCCs.
  
  
  RESULTS
  Vascular and hepatic enhancement in the 400-80 and 500-80 groups was comparable to or greater than that in the 600-120 group (P<.05). Subjective image quality was comparable among the three groups. Sensitivity, specificity, and AUC for detecting HCCs were comparable among the groups. The effective dose was kept low (3.3-4.1 mSv) in all three groups.
  
  
  CONCLUSIONS
  Iodine load can be reduced by 33% in CT of the liver with a combination of 80 kVp tube voltage setting and ASIR technique, without compromising the contrast enhancement, image quality, and detection of HCCs.
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Noda
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan; Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan. Electronic address: masa_gif@yahoo.co.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanematsu
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Goshima
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kondo
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawada
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kawai
authors.affiliation: Department of Radiology and Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Yukichi
authors.initials: Y
authors.lastname: Tanahashi
authors.affiliation: Department of Radiology Services, Gifu University Hospital, 1-1 Yanagido, Gifu 501-1194, Japan.
authors.forename: Toshiharu R T
authors.initials: TRT
authors.lastname: Miyoshi
authors.affiliation: Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Kyongtae T
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging*; D003287:Contrast Media; D058625:End Stage Liver Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007455:Iodine; 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; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media; D007455:Iodine
keywords: Adaptive statistical iterative reconstruction technique; Computed tomography; Contrast material; Liver; Low-tube-voltage