# Diagnostic performance of contrast-enhanced voiding ultrasonography and direct radionuclide cystography with physiologic bladder filling volumes in pediatric vesicoureteral reflux—a prospective study

## TL;DR

This study compares two imaging methods for diagnosing bladder-to-kidney urine backflow in children and finds that a radiation-free ultrasound method works as well as a traditional nuclear imaging method.

## Contribution

Contrast-enhanced voiding ultrasonography is shown to be a radiation-free, effective alternative to direct radionuclide cystography for detecting vesicoureteral reflux in children.

## Key findings

- CEVUS detected VUR in 77.3% of patients and 52.3% of renal units, comparable to DRC.
- CEVUS used more physiological bladder filling volumes than DRC, reducing overfilling risks.
- Both methods had moderate agreement at the renal unit level, with each detecting some cases the other missed.

## Abstract

To compare the diagnostic performance of contrast-enhanced voiding ultrasonography (CEVUS) and direct radionuclide cystography (DRC) at physiological bladder filling volumes in pediatric patients with suspected vesicoureteral reflux (VUR). This prospective, comparative study included 22 children with 44 renal units referred for evaluation due to recurrent urinary tract infections (UTIs). Bladder function was assessed as normal through a four-hour voiding observation or uroflowmetry. All patients underwent both DRC and CEVUS on the same day, using a single catheterization. The investigations were performed by blinded radiologists. The primary outcome was VUR detection in relation to bladder filling volumes. Secondary outcomes included adverse effects and clinical outcomes in relation to radiological findings. DRC detected VUR in 72.7% of patients and 50.0% of renal units, while CEVUS detected VUR in 77.3% and 52.3% respectively. Among patients with paired bladder-filling data at first VUR detection, median bladder filling volume was 37.3% (IQR 26.7–82.4) of expected bladder capacity for DRC and 66.7% (IQR 52.9–87.3) for CEVUS (Wilcoxon signed-rank p = 0.158). At patient level, paired detection rates were comparable between modalities (exact McNemar p = 1.00). At the renal unit level, intermodality agreement was moderate (Cohen’s κ = 0.59; 95% CI 0.35–0.83). DRC detected VUR in 4 renal units negative on CEVUS, whereas CEVUS detected VUR in 5 renal units negative on DRC.

Conclusion: CEVUS was comparable to DRC in VUR detection with physiological bladder filling volumes. As a radiation-free method providing anatomical detail while minimizing bladder overfilling, CEVUS offers a valuable alternative to VUR imaging.

What is Known:• Voiding cystourethrography and direct radionuclide cystography are established imaging modalities for diagnosing vesicoureteral reflux, but both involve ionizing radiation.What is New:• Radiation-free contrast-enhanced voiding ultrasonography detects vesicoureteral reflux using physiologic bladder filling volumes with detection rates comparable to direct radionuclide cystography.

What is Known:

• Voiding cystourethrography and direct radionuclide cystography are established imaging modalities for diagnosing vesicoureteral reflux, but both involve ionizing radiation.

What is New:

• Radiation-free contrast-enhanced voiding ultrasonography detects vesicoureteral reflux using physiologic bladder filling volumes with detection rates comparable to direct radionuclide cystography.