Sonoelastography findings of permanent damage due to chronic urinary infection and vesicoureteral reflux seen in childhood

Purpose: Early and noninvasive detection of permanent renal damage secondary to chronic urinary infections and vesicoureteral reflux seen in childhood. Materials and Methods: We prospectively evaluated 83 patients with chronic urinary infection and/or vesicoureteral reflux that applied to Adnan Menderes University Faculty of Medicine Department of Radiology Ultrasonograhy Unit between January 2015-January 2016 and 100 healthy individuals as control group, and performed Strain Elastography and gray-scale ultrasonograhy in the same session. Scar formation was investigated using DMSA scintigraphy in all the patients. Gray-scale US and SE performed in the same session with Aplio 500 (Toshiba, Japan) using 6-14 MHz, broad band matrix convex transducers. Strain index (SI) values were measured three times in kidneys with scar tissue and average values were obtained. SI value is the ratio of strain value of normal renal cortex tissue (strain R) to strain value of cortical scar tissue (strain T), which is automatically calculated by the US device. Strain index in healthy patients with no cortical scar tissue was calculated by proportioning the strain values obtained from middle pole of the kidney (strain R) and the strain values obtained from upper and lower poles (strain T). Statistical analysis: All data evaluated via SPSS (Statistical Package for Social Sciences, version 18.0, Lead Technologies Inc., USA) program. The conformity of continuous variables to the normal distribution was evaluated with Kolmogrov-Simirnov Test. Mann-Whitney-U test was used to compare non-parametric continuous variables independent groups. Results: İn this study we included 83 patients with chronic urinary infection and/or vesicoureteral reflux evaluated by Adnan Menderes University Faculty of Medicine Department of pediatric nephrology between January 2015-January 2016 and 100 healthy individuals as control group. Scar formation was investigated using DMSA scintigraphy in all the patients. Strain index values were high at all poles of both kidneys, whereas strain index values of upper and lower poles were higher comparing to middle pole of each kidney. We described this difference based on the literature and also our own knowledge and data that disease affect both upper and lower poles because of higher susceptibility in these regions. Using ROC (Receiver Operating Characteristic) analysis based on right kidney upper pole strain index values obtained from both control group and patients without scar formation, we calculated cut-off values with %60-70 and %80 sensitivity, specificity, positive predictive value, negative predictive value. Based on strain index values obtained from control and the patients with no scar formation groups, sensitivity, specificity, positive predictive and negative predictive values at cut-off value of 1.15 were %82, %42, % 36, and % 64 respectively. Conclusion: Chronic urinary infections and vesicoureteral reflux disease are important health problems in childhood. Elastography is a new technique for early detection of scar/fibrosis tissue. The strain index values of scar tissues formed secondary to chronic urinary infections and vesicoureteral reflux were high. The main limitation of strain elastography is that there is no criterion or standard for the pressure applied to the tissue, thus higher compression might affect the elastograhy image and therefore might lead to false interpretation. Studies with larger patient groups and using more standardized elastograhy methods may open the doors for more comprehensive assessment and verification of the results and findings in the future.