Use of CT Scout Radiographs in the Management of Urolithiasis

Unenhanced CT is the gold standard imaging for patients with suspected urolithiasis. The aim of this study was to determine the sensitivity of CT scout radiographs in detecting urinary stones in patients with confirmed urolithiasis on unenhanced CT. A retrospective study was carried out with data collected consecutively from January to November 2021. The included cases were those with confirmed urinary stones on unenhanced CT. CT scout radiographs were read and cross-referenced with unenhanced CT. Stones were classified as visible and non-visible on scout radiographs. The location and size of stones on axial CT were recorded. Means of size of visible and non-visible stones and frequency of detection by scout radiographs between proximal stones and distal stones were tested for significance. 117 stones were analyzed. The sensitivity of CT scout radiographs was 56%. There was a direct correlation between stone size and stone visibility on CT scout radiographs. There was a statistically significant difference between the means of sizes of visible and non-visible stones on scout radiographs (P < 0.001). 54% (41/76) of proximal stones and 59% (24/41) of distal stones were visible on CT scout radiographs. There was no statistically significant difference between visibility and stone location (P = 0.6). Conclusion: CT scout radiography could detect stones in 56% of patients with urolithiasis diagnosed on unenhanced CT. Therefore, it could serve as a baseline investigation to detect stone radio-opacity and should be reported in conjunction with the findings of unenhanced CT for guiding treatment/follow-up decision options.