title: CT portography by multidetector helical CT: comparison of three rendering models.
abstract: OBJECTIVE
  To assess the value of multidetector CT portography in visualizing varices and portosystemic collaterals in comparison with conventional portography, and to compare the visualizations obtained by three rendering models (volume rendering, VR; minimum intensity projection, MIP; and shaded surface display, SSD).
  
  
  METHODS
  A total of 46 patients with portal hypertension were examined by CT and conventional portography for evaluation of portosystemic collaterals. CT portography was performed by multidetector CT (MD-CT) scanner with a slice thickness of 2.5 mm and table feed of 7.5 mm. Three types of CT portographic models were generated and compared with transarterial portography.
  
  
  RESULTS
  Among the 46 patients, 48 collaterals were identified on CT transverse images, while 38 collaterals were detected on transarterial portography. Forty-four of 48 collaterals identified on CT transverse images were visualized with the MIP model, while 34 and 29 collaterals were visualized by the VR and SSD methods, respectively. The average CT value for the portal vein and varices was 198 HU with data acquisition of 50 sec after contrast material injection.
  
  
  CONCLUSIONS
  CT portography by multidetector CT provides excellent images in the visualization of portosystemic collaterals. The images of collaterals produced by MD-CT are superior to those of transarterial portography. Among the three rendering techniques, MIP provides the best visualization of portosystemic collaterals.
authors.affiliation: Department of Radiology, Kumamoto University School of Medicine, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Nakayama
authors.forename: Masanori
authors.initials: M
authors.lastname: Imuta
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.forename: Masataka
authors.initials: M
authors.lastname: Kadota
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.forename: Shinya
authors.initials: S
authors.lastname: Shiraishi
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Hayashida
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D003097:Collateral Circulation; D004932:Esophageal and Gastric Varices / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D006975:Hypertension, Portal / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011169:Portal Vein / Q000000981:diagnostic imaging; D011172:Portography / Q000379:methods; D036542:Tomography, Spiral Computed