CT Scout Topograms

Published Date: 19th July 2016

Publication Authors: Massey G, , McCabe JE,

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Objective

Guidelines for the diagnosis and management of new presentations of urolithiasis recommend performing both X-Ray Kidney-Ureter-Bladder (XR-KUB) and CT Kidney-Ureter- Bladder (CT-KUB). We assessed the sensitivity of the CT scout topogram compared with XR-KUB in the detection of urinary tract calculi.

Methods 

Patients that underwent both XR-KUB and CT-KUB with confirmed urolithiasis were identified over a 1 year period. Two clinicians within our department individually reviewed initial XR-KUB films and where radio-opaque urinary tract calculi were identified, CT-KUB scout topogram from the initial presentation were also examined. 

Results

Of the 79 patients identified, radio-opaque stones were detected in 64 (81%) on XR-KUB. Analysis of CT-KUB scout topograms for these 64 patients revealed that 57 (89%) had visible calculi. The mean stone size for calculi visible on CT-KUB scout topogram was 8.3mm. However the mean stone size was smaller at 5.1mm for stones not visible on the topogram.

Conclusions

We have demonstrated that the vast majority of renal tract calculi visualised on XR-KUB can also be detected on CT-KUB scout topogram. We propose that CT-KUB should be performed initially, followed by review and reporting of the scout topogram; thus avoiding further radiation exposure from XR-KUB (0.80 mSv), as well as decreasing cost. We suggest that XR-KUB should only be performed subsequently if the stone is not visualised on the CT-KUB scout topogram.

Patrick, NL; Iskander, M; Massey, G; Samsudin, A; Mccabe, J. (2012).  Sensitivity of ct scout topograms in the identification of radio-opaque urinary tract calculi . Journal of Endourology. 26 (S1), A416

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