Sensitivity and value of digital CT scout radiography for detecting ureteral stones in patients with ureterolithiasis diagnosed on unenhanced CT.

When unenhanced CT reveals ureterolithiasis, some patients will require baseline or follow-up conventional radiography to help guide clinical management. We sought to determine the sensitivity of routinely obtained scout radiographs for revealing stones to determine if the scout view can be used in place of baseline conventional radiography.We retrospectively reviewed the CT scout radiographs in conjunction with axial CT images in a series of 215 consecutive patients in whom CT revealed a single ureteral stone. On the scout radiographs, stones were classified as definitely visible, definitely not visible, or indeterminate. In addition, a phantom was constructed using fragments of kidney stones to evaluate the effect of the digital scout kilovoltage settings on stone visualization.Forty-nine percent of stones were definitely visible on scout radiography, 47% were definitely not visible, and 4% were indeterminate. Four stones larger than 10 mm that were not visible on scout radiography were composed of uric...