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. 2017 Apr 6;12(4):e0174800.
doi: 10.1371/journal.pone.0174800. eCollection 2017.

Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system

Hiroshi Juri  1 , Takahiro Tsuboyama  2 , Mitsuhiro Koyama  1 , Kiyohito Yamamoto  1 , Go Nakai  1 , Atsushi Nakamoto  2 , Kazuhiro Yamamoto  1 , Haruhito Azuma  3 , Yoshifumi Narumi  1
Affiliations

Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system

Hiroshi Juri et al. PLoS One. .

Abstract

Objective: To prospectively evaluate the ability of CT urography with a low-dose multi-phasic excretory phase for opacification of the urinary system.

Materials and 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.

Conclusion: 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.

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Conflict of interest statement

Competing Interests: Both Toshiba Medical Systems and Daiichi Sankyo provided support in the form of research materials (Toshiba Medical Systems: adaptive iterative reconstruction algorithm; Daiichi Sankyo: contrast media). HJ and TT have received occasional travel and accommodation support from Toshiba Medical Systems, but were not provided direct funding for this study. None of the authors are employed by Toshiba Medical Systems or Daiichi Sankyo. These affiliations do not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1
Fig 1. Examples of the evaluation of opacification scores of the proximal ureter on maximum intensity projection (MIP) images.
A, A 5-minute delay scored as 1 (<50%); B, A 5-minute delay scored as 2 (51–99%); and C, A 5-minute delay scored as 3 (100%).
Fig 2
Fig 2. Axial CT images obtained in the excretory phase with a 5-minute delay in a 67-year-old man, with ROIs manually drawn at the anterior and posterior portions of the urinary bladder.
The sizes of the ROIs were kept constant on the anterior and posterior portions with a copy-and-paste function.
Fig 3
Fig 3. Maximum intensity projection images show the upper urinary tracts obtained in the three excretory phases in a 44-year-old man.
A, Excretory phase with a 5-minute delay. B, Excretory phase with a 10-minute delay. C, Excretory phase with a 15-minute delay. With a 5-minute delay, non-opacification was noted in the right ureter, but with a 10- or 15-minute delay, the non-opacified segments were delineated. On the other hand, just a 5-minute delay was sufficient for complete opacification of the left ureter. The numbers of completely opacified segments were 5, 4, 6, 6, 7, 7, and 8 with the 5-, 10-, 15-, 5 + 10-, 5 + 15-, 10 + 15-, and 5 + 10 + 15-minute delays, respectively. Multi-phasic acquisition was thus able to delineate more segments.
See this image and copyright information in PMC

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