Evaluation of renal parenchymal stiffness by shear wave us elastography

Purpose: To investigate the concordance of renal parenchymal stiffness values measured by Shear Wave Elastography(SWE) technique with clinical and laboratory findings in the evaluation of the severity of the disease in patients with chronic kidney disease(CKD) and their contribution to the diagnosis. Materials and Methods: Fifty patients with histopathologically proven or with clinical and laboratory findings of CKD who underwent abdominal, renal or urinary ultrasonography(US) examination in our department between December 2020-November 2022, were evaluated. Due to inadequate measurements, 9 patients were excluded from the study and 41 patients were enrolled. Our control group consisted of 40 patients over 18 years of age who did not have any laboratory or imaging-proven renal disease and had an US appointment in our clinic for other reasons. All sonographic examinations and SWE measurements were performed by the same radiologist. After the evaluation of renal size, mean parenchymal thickness and echogenicity, renal parenchymal stiffness was measured by SWE method. In each patient, a ROI was placed parallel to the renal pyramids in the lower pole, middle section and upper pole of each kidney, and the mean value was determined in kPa, by making at least two measurements for each section and at least 6 measurements in total for each kidney. In order to determine the presence and severity of CKD, blood test results(serum urea, creatinine, glomerular filtration rate(GFR)) from the instutional electronic database, which provided information about renal function and which were obtained at the time of US examination, were recorded. Using the obtained data, it was investigated whether there was a correlation between renal parenchymal stiffness values measured by SWE and laboratory data used in the diagnosis and staging of the disease. Spearman correlation test was used in statistical analyses. Results: Of the 41 patients included in the study, 24 patients(58.5%) were female and 17 patients(42.5%) were male. The age range was between 18 years and 83 years, with a mean age of 66 years. Hypertension and diabetes mellitus were the most common causes of CKD. We found that parenchymal stiffness values were statistically significantly higher in patients with CKD compared to the control group(15.6 kPa-5.5 kPa, respectively)(p<0,001). A statistically significant positive correlation was found between renal parenchymal stiffness and serum urea and creatinine levels and there was a statistically significant negative correlation between renal parenchymal stiffness and GFR values(p<0.001), in concordance with the literature. No significant correlation was found between renal parenchymal stiffness values and patient age in our study(p>0.05). In addition, no significant correlation was found between gender and renal parenchymal stiffness(p>0.05). Conclusion: US, is a is fast, easy to perform, noninvasive, and portable imaging method which lacks ionising radiation. SWE, is an effective noninvasive technique that shows fibrosis in many parenchymal organs, especially the liver, and renal parenchymal stiffness values measured by SWE, may be useful in the assessment of renal function and disease severity in patients with CKD. As it is a reproducible technique, we believe that with the increasing use of this technique, and with technical improvements, standardisation of measurements and definition of reference values, SWE might play an important role in the diagnosis and follow-up of patients with CKD. Keywords: Sonoelastography, Chronic Kidney Disease