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

View Article: PubMed Central - PubMed

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.

No MeSH data available.


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%).
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pone.0174800.g001: 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%).

Mentions: Qualitative analysis―Two radiologists with 12 and 7 years of experience in abdominal CT reviewed the EP images using a Picture Archiving and Communication System (PACS) with a preset window level and a window width of 200/600 HU, and performed independent visual evaluations. They were blinded to the patient’s clinical data and to any prior or follow-up imaging results. They evaluated the axial, coronal and MIP images in the three EPs. The upper urinary tracts were classified into 4 segments: the renal collecting system, proximal ureter (the ureteropelvic junction to the iliac crest), middle ureter (the iliac crest to the crossing of the iliac vessels), and distal ureter (the crossing of the iliac vessels to the ureterovesical junction), and each segment on each of the three EPs with 5-, 10-, and 15-minute delays was scored in regard to opacification as follows: 1, <50% opacification; 2, 50–99%; 3, 100% (Fig 1). The urinary bladder was assigned an opacification score for each EP using a 5-point scoring system: 1, <25% opacification; 2, 25‒49%; 3, 50‒74%; 4, 75‒99%; 5, 100% opacification on each EP. Discrepancies in the opacification scores between the two readers were resolved by consensus.


Assessment of the ability of CT urography with low-dose multi-phasic excretory phases for opacification of the urinary system
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%).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383231&req=5

pone.0174800.g001: 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%).
Mentions: Qualitative analysis―Two radiologists with 12 and 7 years of experience in abdominal CT reviewed the EP images using a Picture Archiving and Communication System (PACS) with a preset window level and a window width of 200/600 HU, and performed independent visual evaluations. They were blinded to the patient’s clinical data and to any prior or follow-up imaging results. They evaluated the axial, coronal and MIP images in the three EPs. The upper urinary tracts were classified into 4 segments: the renal collecting system, proximal ureter (the ureteropelvic junction to the iliac crest), middle ureter (the iliac crest to the crossing of the iliac vessels), and distal ureter (the crossing of the iliac vessels to the ureterovesical junction), and each segment on each of the three EPs with 5-, 10-, and 15-minute delays was scored in regard to opacification as follows: 1, <50% opacification; 2, 50–99%; 3, 100% (Fig 1). The urinary bladder was assigned an opacification score for each EP using a 5-point scoring system: 1, <25% opacification; 2, 25‒49%; 3, 50‒74%; 4, 75‒99%; 5, 100% opacification on each EP. Discrepancies in the opacification scores between the two readers were resolved by consensus.

View Article: PubMed Central - PubMed

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 (&gt;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&lt;0.001) and complete opacification (21.9, 53.1, and 81.3%, respectively; P&lt;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.

No MeSH data available.