title: Improving image quality in portal venography with spectral CT imaging.
abstract: OBJECTIVE
  To investigate the effect of energy spectral CT on the image quality of CT portal venography in cirrhosis patients.
  
  
  METHODS
  30 portal hypertension patients underwent spectral CT examination using a single-tube, fast dual tube voltage switching technique. 101 sets of monochromatic images were generated from 40keV to 140keV. Image noise and contrast-to-noise ratio (CNR) for portal veins from the monochromatic images were measured. An optimal monochromatic image set was selected for obtaining the best CNR for portal veins. The image noise and CNR of the intra-hepatic portal vein and extra-hepatic main stem at the selected monochromatic level were compared with those from the conventional polychromatic images. Image quality was also assessed and compared.
  
  
  RESULTS
  The monochromatic images at 51keV were found to provide the best CNR for both the intra-hepatic and extra-hepatic portal veins. At this energy level, the monochromatic images had about 100% higher CNR than the polychromatic images with a moderate 30% noise increase. The qualitative image quality assessment was also statistically higher with monochromatic images at 51keV.
  
  
  CONCLUSIONS
  Monochromatic images at 51keV for CT portal venography could improve CNR for displaying hepatic portal veins and improve the overall image quality.
authors: Department of Radiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing,100050, China. zhaolqzr@sohu.com
authors: Li-qin
authors: LQ
authors: Zhao
authors: Wen
authors: W
authors: He
authors: Jian-ying
authors: JY
authors: Li
authors: Jiang-hong
authors: JH
authors: Chen
authors: Ke-yang
authors: KY
authors: Wang
authors: Li
authors: L
authors: Tan
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D006975:Hypertension, Portal / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010690:Phlebography / Q000379:methods*; D011169:Portal Vein / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*