Contrast-enhanced ultrasonography (voiding urosonography) of vesicoureteral reflux: state of the art

Three methods are currently used to identify vesicoureteral reflux (VUR) in children, namely, radiographic voiding cystourethrography, radionuclide voiding cystography and, more recently, echo-enhanced voiding urosonography (VUS). Recent advances in tissue-harmonic and contrast-specific imaging techniques, together with the development of second-generation contrast agents, have improved the potential of ultrasonography both in the diagnosis and grading of VUR in children. Today, VUS is able to accurately assess the grade of reflux and the state of the urethra, previously considered fundamental limitations to the extensive use of this technique. The aim of our paper is to review the role of ultrasonography in the diagnosis of VUR, from the initial experiences up to the recent use of second-generation microbubbles combined with contrast-specific low-mechanical-index software. We discuss the advantages and limits of VUS with respect to radiographic and radionuclide imaging in the light of an analysis of the most recent literature, and we described the new VUS study technique using second-generation contrast media. Growing requests by paediatric nephrologists and surgeons require that even general radiologists become familiar with this technique.