Delineation of upper urinary tract segments at MDCT urography in patients with extra-urinary mass lesions: retrospective comparison of standard and low-dose protocols for the excretory phase of imaging.
OBJECTIVE
Excretory-phase CT urography (CTU) may replace excretory urography in patients without urinary tumors. However, radiation exposure is a concern. We retrospectively compared upper urinary tract (UUT) delineation in low-dose and standard CTU.


METHODS
CTU (1-2 phases, 120 KV, 4 × 2.5 mm, pitch 0.875, i.v. non-ionic contrast media, iodine 36 g) was obtained with standard (14 patients, n = 27 UUTs, average 175.6 mAs/slice, average delay 16.8 min) or low-dose (26 patients, n = 86 UUTs, 29 mAs/slice, average delay 19.6 min) protocols. UUT was segmented into intrarenal collecting system (IRCS), upper, middle, and lower ureter (UU,MU,LU). Two independent readers (R1,R2) graded UUT segments as 1-not delineated, 2-partially delineated, 3-completely delineated (noisy margins), 4-completely delineated (clear margins). Chi-square statistics were calculated for partial versus complete delineation and complete delineation (clear margins), respectively.


RESULTS
Complete delineation of UUT was similar in standard and low-dose CTU (R1, p > 0.15; R2, p > 0.2). IRCS, UU, and MU clearly delineated similarly often in standard and low-dose CTU (R1, p > 0.25; R2, p > 0.1). LU clearly delineated more often in standard protocols (R1, 18/6 standard, 38/31 low-dose, p > 0.1; R2 18/6 standard, 21/48 low-dose, p < 0.05).


CONCLUSIONS
Low-dose CTU sufficiently delineated course of UUT and may locate obstruction/dilation, but appears unlikely to find intraluminal LU lesions.
Mueller-Lisse
Ulrike L
UL
Department of Urology, University of Munich, Munich, Germany. Ulrike.Mueller-Lisse@med.uni-muenchen.de
Coppenrath
Eva M
EM
Meindl
Thomas
T
Degenhart
Christoph
C
Scherr
Michael K
MK
Stief
Christian G
CG
Reiser
Maximilian F
MF
Mueller-Lisse
Ullrich G
UG
D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000000981:diagnostic imaging*; D017410:Practice Guidelines as Topic; D011829:Radiation Dosage; D011835:Radiation Protection / Q000592:standards*; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards*; D014554:Urination; D014567:Urography / Q000379:methods*
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