Diagnosis of vesicoureteric reflux with low-dose contrast-enhanced harmonic ultrasound imaging

Background: Harmonic US imaging has been shown to be better than conventional US for the detection and visualisation of microbubbles in contrast-enhanced voiding urosonography (VUS). Objective: To determine the diagnostic efficacy of VUS using a reduced dose of the US contrast medium in comparison to voiding cystourethrography (VCUG). Materials and methods: Fifty-five children (17 boys, 38 girls; mean age 4 years) were recruited. All patients underwent VUS by harmonic imaging followed by VCUG. The dose of the US contrast medium (Levovist) administered intravesically was half of the recommended dose i.e. 5% of the bladder filling volume. Results: A total of 114 kidney-ureter (K-U) units were available for evaluation. Vesicoureteric reflux (VUR) was detected in 29 K-U units by one or both examination modalities. There was a 91.2% concordance rate between VUS and VCUG. VUR in seven and three K-U units were detected only by VUS and VCUG, respectively. Taking VCUG as the reference method, VUS had the following diagnostic results: 86.4% sensitivity, 92.4% specificity, positive and negative predictive values of 73.1 and 96.6%, respectively. Conclusions: Even when the dose of US contrast medium is halved, the diagnostic efficacy of harmonic VUS is comparable to VCUG. Consequently, we recommend an US contrast medium dose of 5% of the bladder filling volume for the diagnosis of VUR using contrast-enhanced harmonic VUS.