title: Optimal Adaptive Statistical Iterative Reconstruction Percentage in Dual-energy Monochromatic CT Portal Venography.
abstract: OBJECTIVE
  The aim of this article was to study the influence of different adaptive statistical iterative reconstruction (ASIR) percentages on the image quality of dual-energy computed tomography (DECT) portal venography in portal hypertension patients.
  
  
  METHODS
  DECT scans of 40 patients with cirrhosis (mean age, 56 years) at the portal venous phase were retrospectively analyzed. Monochromatic images at 60 and 70 keV were reconstructed with four ASIR percentages: 0%, 30%, 50%, and 70%. Computed tomography (CT) numbers of the portal veins (PVs), liver parenchyma, and subcutaneous fat tissue in the abdomen were measured. The standard deviation from the region of interest of the liver parenchyma was interpreted as the objective image noise (IN). The contrast-noise ratio (CNR) between PV and liver parenchyma was calculated. The diagnostic acceptability (DA) and sharpness of PV margins were obtained using a 5-point score. The IN, CNR, DA, and sharpness of PV were compared among the eight groups with different keV + ASIR level combinations.
  
  
  RESULTS
  The IN, CNR, DA, and sharpness of PV of different keV + ASIR groups were all statistically different (P < 0.05). In the eight groups, the best and worst CNR were obtained in the 60 keV + 70% ASIR and 70 keV + 0% ASIR (filtered back-projection [FBP]) combination, respectively, whereas the largest and smallest objective IN were obtained in the 60 keV + 0% ASIR (FBP) and 70 keV + 70% combination. The highest DA and sharpness values of PV were obtained at 50% ASIR for 60 keV.
  
  
  CONCLUSIONS
  An optimal ASIR percentage (50%) combined with an appropriate monochromatic energy level (60 keV) provides the highest DA in portal venography imaging, whereas for the higher monochromatic energy (70 keV) images, 30% ASIR provides the highest image quality, with less IN than 60 keV with 50% ASIR.
authors.affiliation: Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yong' An Road, Xi Cheng District, Beijing 100050, China.
authors.forename: Liqin
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Winklhofer
authors.affiliation: Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yong' An Road, Xi Cheng District, Beijing 100050, China. Electronic address: zhenghanyang@263.net.
authors.forename: Zhenghan
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yong' An Road, Xi Cheng District, Beijing 100050, China.
authors.forename: Keyang
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Radiology, Beijing Friendship Hospital, Capital Medical University, No. 95, Yong' An Road, Xi Cheng District, Beijing 100050, China.
authors.forename: Wen
authors.initials: W
authors.lastname: He
mesh_terms: D050153:Abdominal Fat / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D005260:Female; D006509:Hepatitis B / Q000000981:diagnostic imaging; D006526:Hepatitis C / Q000000981:diagnostic imaging; D006801:Humans; D006975:Hypertension, Portal / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D008099:Liver / Q000000981:diagnostic imaging; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging; D008104:Liver Cirrhosis, Alcoholic / Q000000981:diagnostic imaging; D008105:Liver Cirrhosis, Biliary / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000706:statistics & numerical data*; D011172:Portography / Q000706:statistics & numerical data*; D011860:Radiography, Abdominal / Q000706:statistics & numerical data; D015900:Radiography, Dual-Energy Scanned Projection / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D050151:Subcutaneous Fat / Q000000981:diagnostic imaging
keywords: ASIR; BMI; Dual-energy CT; Portal vein; keV