Radiation exposure in vesicoureteral reflux diagnostics: a comparative study of direct radionuclide cystography and voiding cystourethrogram.

Introduction: Voiding cystourethrography (VCUG) is the standard method for diagnosing vesicoureteral reflux (VUR) but has been criticized for radiation exposure. Direct radionuclide cystography (DRC) was developed to reduce this risk. We aimed to assess DRC's efficacy as a screening tool and compare its radiation burden to VCUG.

Materials and methods: We retrospectively analyzed patient records encompassing children who underwent VCUG or DRC to diagnose VUR from 2011 to 2020 at our hospital.

Results: A total of 156 children were included (median age: 0.75 years, 53.8% females). Indications included urinary tract infection in 71.2% of patients and antenatal hydronephrosis in 26.9%. DRC was performed on 122 patients (78.2%) and VCUG on 96 patients (61.5%), with solitary use in 38.5 and 21.8% of cases, respectively, and combined application in 39.7%. DRC detected VUR in 35.3% (43/122) and VCUG in 61.5% (59/96) of patients. Bladder-filling rates differed significantly between DRC (37%) and VCUG (67%) (P < 0.0001). Median radiation doses were lower in VCUG (0.023 mSv) than in DRC (0.073 mSv). For patients requiring complementary VCUG after DRC, the median radiation dose for DRC was 0.063 mSv (P < 0.0001), resulting in a total median dose of 0.098 mSv. Cost analysis revealed VCUG as more cost-effective, with an additional expenditure of approximately 345 euros per patient undergoing DRC in our cohort.

Conclusion: DRC imposed a higher radiation burden on patients than VCUG and often necessitated follow-up VCUG for positive cases. This challenges the utility of DRC as a low-radiation alternative in VUR screening.

Level of evidence: Level 4: cohort study without a control group.