title: Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system.
abstract: OBJECTIVE
  To prospectively evaluate the ability of CT urography with a low-dose multi-phasic excretory phase for opacification of the urinary system.
  
  
  METHODS
  Thirty-two patients underwent CT urography with low-dose multi-phasic s using adaptive iterative dose reduction 3D acquired at 5-, 10-, and 15-minute delays. Opacification scores of the upper urinary tracts and the urinary bladder were assigned for each excretory phase by two radiologists, who recorded whether adequate (>75%) or complete (100%) opacification of the upper urinary tract and urinary bladder was achieved in each patient. Adequate and complete opacification rates of the upper urinary tracts and the urinary bladder were compared among three excretory phases and among combined multi-phasic excretory phases using Cochran's Q test.
  
  
  RESULTS
  There was no significant difference among three excretory phases with 5-, 10-, and 15-minute delays in adequate (56.3, 43.8, and 63.5%, respectively; P = 0.174) and complete opacification rates (9.3, 15.6, and 18.7%, respectively; P = 0.417) of the upper urinary tracts. Combined tri-phasic excretory phases significantly improved adequate and complete opacification rates to 84.4% and 43.8%, respectively (P = 0.002). In contrast, there were significant differences among three excretory phases for the rate of adequate (31.3, 84.4, and 93.8%, respectively; P<0.001) and complete opacification (21.9, 53.1, and 81.3%, respectively; P<0.001) of the urinary bladder. Multi-phasic excretory phases did not improve these rates because opacification was always better with a longer delay.
  
  
  CONCLUSIONS
  Although multi-phasic acquisition of excretory phases is effective at improving opacification of the upper urinary tracts, complete opacification is difficult even with tri-phasic acquisition.
authors.affiliation: Department of Radiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Juri
authors.affiliation: Department of Radiology, Osaka University School of Medicine, 2-15 Yamadaoka, Suita, Osaka, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuboyama
authors.affiliation: Department of Radiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Koyama
authors.affiliation: Department of Radiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Kiyohito
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Department of Radiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Nakai
authors.affiliation: Department of Radiology, Osaka University School of Medicine, 2-15 Yamadaoka, Suita, Osaka, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakamoto
authors.affiliation: Department of Radiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Department of Urology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Haruhito
authors.initials: H
authors.lastname: Azuma
authors.affiliation: Department of Radiology, Osaka Medical College, 2-7, Daigaku-machi, Takatsuki, Osaka, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Narumi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*; D001743:Urinary Bladder / Q000000981:diagnostic imaging*; D014567:Urography / Q000379:methods*