Assessment of the sensitivity of ct scout radiograph in detecting ureterolithasis on non contrast computed tomography as gold standard, Tikur Anbessa specialized hospital, Addis Ababa,Ethiopia
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Date
2018-10
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Addis Ababa University
Abstract
Introduction: Imaging plays an important role in the management of patients with urinary
stone disease including initial diagnosis, treatment planning and follow up after medical therapy
or urologic interventions. There is high variability in determining the choice of imaging
protocols to observe progression of ureteral calculi for follow up. Noncontract computerized
tomography for kidney ureter bladder (NCCT or CT KUB) scan has become widely accepted as
gold standard and imaging study of choice for examining patients with acute flank pain. Scout
view is always included as an essential part of NCCT. Some have proposed using scout view in
management of ureteric calculi owing to its reduced radiation dose. Therefore, our study aim was
to assess the sensitivity of CT scout radiography for detecting ureteral stones in patients with
ureterolithiasis diagnosed on NCCT as a standard reference.
Methodology: Institutional based cross-sectional prospective study was conducted over an
11month (between September 30, 2017, and August 7, 2018) study period in Radiology
department of TASH. A total of 86 patients who has undergone NCCT KUB were assessed for
initial eligibility. Out of these, 58 were enrolled in this study which had ureteric calculi.
Location of the stone, size, density characteristic of the stone was determined from the NCCT
KUB. Moreover, the visibility of that stone on scout radiograph was documented by a radiologist
who was blinded for NCCT findings. The sensitivity, positive and negative predictive value of
the scout films were calculated in reference to NCCT. Before statistical analysis, data was first
checked manually for completeness and then coded and entered in to SPSS and analyzed using
SPSS version 21.0. Level of significance (p < 0.05) and CI (95%) was employed. Results were
presented in graphs, charts and texts.
Results: A total of seventy-six calculi were analyzed from fifty-eight patients who had ureteric
calculi. Of the 76 total ureteric calculi stones, 37(48.7%) were definitely visible on the scout
radiograph, 34(44.7%) were definitely not visible, and 5 (6.6%) were indeterminate, which
giving a sensitivity of 48.7 %. On the basis of stone location, the sensitivity of the scout view for
stone detection was as follows: proximal ureter, 56%; mid ureter, 37%; distal ureter, 50%; and
ureterovesical junction, 37%. On the basis of stone size category, the sensitivity of the scout view
for stone detection was as follows: < 4mm, 33%; 4-8 mm, 48%; and >8 mm, 52% as well the
mean size of stones visible on the scout view was 8.36 mm. Mean HU visible on scout was 779
HU in the range 344-1601HU.
Conclusion: In our study, 48.7% of ureteral stones were visible on the often overlooked
routine CT scout radiograph. Therefore, the CT scout view should be encouraged and reported
routinely in conjunction with CT KUB as a baseline for treatment follow up. It may avoid the
need for obtaining a conventional radiograph at the time of diagnosis. So, we will postulate, it is
good practice to report if the calculus is visible on the scanogram of the study to establish if a plain KUB radiograph is sufficient for follow up purposes rather than a higher radiation CT study.
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Keywords
medical therapy,adiography