Ultrasound elastographic evaluation of renal parenchyma in pediatric patients with vesicoureteral reflux.

Abstract

Objective: The most common chronic complication of vesicoureteral reflux (VUR) is the presence of renal scarring and dimercapto succinic acid (DMSA) renal scan is utilized for its detection. In this study, we have aimed to assess whether shear wave speed (SWS) differs between normal and refluxing kidneys.

Materials and method: Fifty pediatric VUR patients and 21 healthy children with available DMSA obtained within the previous year were included in the study. In the patient group, with grade 3, 4 and 5 kidney reflux were defined as "kidneys with high-grade reflux", and were subdivided into scarred and unscarred kidneys. In the VUR group population, kidneys with grade 1 and 2 reflux were defined as "r kidneys with low-grade reflux", and in VUR group with unilateral reflux, kidneys on the non-reflux side were defined as "contralateral non-refluxing kidneys". A total of 42 kidneys in the non-VUR group of 21 patients were defined as "non-VUR kidneys". The control non-VUR group included children who had DMSA scans for non-urological reasons (e.g., unexplained fever or abdominal pain), and showed no VUR. Three VUR group had solitary kidney and a total of 139 kidneys were investigated. Ultrasound elastography evaluation of the upper, middle and lower zones of the kidneys was performed. Three regions of interest (ROIs) were placed in each zone to evaluate the cortex, excluding the capsule and medulla as much as possible during measurements. A total of 9 measurements were performed in each kidneys and the mean shearwave elastography (SWE) speeds of the parenchyma were recorded in m/sec.

Results: We have found that the SWS were significantly higher in kidneys with DMSA-proven scarring compared to those without scarring and to the control group (p < 0.05). In the Receiver Operating Characteristic (ROC) analysis performed, SWS of 2.06 m/s had 83.7 % sensitivity (95 % confidence Interval (CI) 70.3-92.7) and 76.5 % specificity (95 % CI 50.1-93.2; p < 0.001; AUC: 0.795) in differentiating between scarred and non-scarred kidneys with high-grade reflux (Figure 2).

Conclusion: In conclusion, shear wave elastography can differentiate between renal functional units with and without DMSA-proven scarring. Although the precise scar location was not assessed, SWE appears to reflect global changes in cortical stiffness. Its non-invasive nature and accessibility make it a promising adjunct to conventional imaging methods.