Low contrast dose voiding urosonography in children with phase inversion imaging

Voiding urosonography (VUS) using a microbubble contrast agent has been introduced as an alternative technique in the diagnosis of vesicoureteral reflux (VUR). This study was undertaken to assess if phase inversion ultrasound (PIUS), a recent microbubble specific imaging technique, has advantages over fundamental in VUS and if it allows a reduction of contrast agent dose. Forty-three children with suspected VUR (aged 3 days–12 years, average of 3.9 years) with 92 kidney-ureter units (KUU) were included. Everyone obtained a baseline US scan that was followed by VUS using Levovist as the contrast agent. Constant switching between fundamental and PIUS performed the enhanced part for comparison. Every child underwent VCUG immediately afterwards. Contrast enhancement was stronger and longer lasting on PIUS than on fundamental US in all 43 cases. Reflux was detected in a total of 21 KUU, out of 92 KUU (23%). PIUS revealed VUR in 18; fundamental in 14 KUU and VCUG depicted 16 cases of reflux (p≥0.29). The mean volume of Levovist dose administered to the bladder was 7.4±3.4% of the bladder volume. VUS using PI mode provided considerably stronger and longer enhancement and slightly improved the detection of VUR. It allowed a reduction of contrast dose and cost by approximately 35% over current dose recommendations for fundamental US.