A quantitative grading system of vesicoureteral reflux by contrastenhanced voiding urosonography

Aims: Contrast-enhanced voiding urosonography (ceVUS) is a well-established imaging modality for the diagnosis of vesicoureteral reflux (VUR). However, discrepancies of grading diagnosis of VUR exist due to the qualitative grading criteria currently used in clinics. This study aimed to evaluate numerical markers for a quantitative VUR grading system. Material and methods: CeVUS images of grade II-VVUR were analysed. A quantitative indicator, i.e. sectional area ratio (SAR), on the imaging section with maximum cross-section area and the presence of kidney hilum was calculated to distinguish different grades of VUR. The diagnostic performance of SAR was evaluated using receiver operating characteristic curve (ROC) analysis, and the maximum Youden Index was used to determine the optimal cut-off values. Results: A total of 63 patients with 126 PelviUreteral Units were enrolled. The SAR value increased significantly along with the increase of VUR grade. SAR had an excellent diagnostic performance in grading VUR. For differentiating VUR of grade II vs III, III vs IV and IV vs V, the area under the ROC curve values of SAR were 0.967, 0.943 and 0.865, respectively, while the optimal SAR cut-off values were 14.3%, 34.9% and 51.0%, respectively. The quantitative grading system based on the optimal SAR cut-off values showed excellent consistency with the qualitative grading system of VUR currently used in clinic. Conclusions: The numerical indicator SAR calculated from ceVUS may be used to establish a quantitative VUR grading system with excellent diagnostic performance and can potentially serve as a reliable tool for the evaluation and follow-up of VUR.