Comparative CT scout view and KUB radiography for ureteral stone detection in an ESWL cohort

Purpose To compare the sensitivity of CT scout view and kidney-ureter-bladder (KUB) radiography for ureteral stone detection in patients scheduled for extracorporeal shock wave lithotripsy (ESWL) and identify factors influencing stone visibility. Methods We conducted a retrospective single-center study including consecutive patients presenting with renal colic between January 2023 and December 2024. Patients with ureteral stones confirmed on non-contrast computed tomography (NCCT) and referred for ESWL were included. Stones with a density < 400 Hounsfield Units were excluded. CT scout view and KUB radiographs were reviewed. Sensitivities were compared using the McNemar test. Factors associated with detectability were assessed using univariate analysis and Firth's penalized logistic regression. Results Fifty-six stones in 49 patients were analyzed. Overall sensitivity was 58.9% for CT scout view and 66.1% for KUB, with no significant difference (p=0.50). Detection varied according to stone location: scout view performed better for pelvic stones (69.6% vs. 56.5%), whereas KUB showed higher sensitivity for lumbar (73.1% vs. 53.8%) and pyeloureteral stones (75.0% vs. 50.0%). Among stones not detected on scout view, 52% were identified on KUB, while 48% remained undetected on both modalities. Stone density was independently associated with scout view detectability (p=0.029), whereas no significant predictors were identified for KUB. Conclusion In this pre-selected ESWL cohort, overall stone detection sensitivity did not differ significantly between CT scout view and KUB radiography, although visibility was location-dependent. A selective imaging strategy based on initial scout view assessment remains a hypothetical model requiring formal prospective validation. Level of evidence : 3.