A comparison of normal kidneys to those with chronic kidney disease using ultrasound shearwave elastography

Abstract

Background Chronic kidney disease (CKD) is based on estimated glomerular filtration rate (eGFR) results in blood analysis. Patients also undergo diagnostic ultrasound to confirm and supplement the eGFR findings. Renal fibrosis is the end stage of CKD and has been subjectively evaluated with renal ultrasound. This study was designed to determine if patients with CKD will have a stiffer renal cortex compared to a normal control group using ultrasound shearwave elastography (SWE) in a quantifiable manner. Objectives The aim of this study is to measure and compare the renal cortical stiffness Young Modulus values in kilopascals (kPa) using SWE for normal and CKD participants. Methods Outpatient volunteers were recruited for this study. All participants were greater than 18 years of age. The normal control group had an eGFR results of greater than 90, while the CKD group had an eGFR of less than 60, within three months of the SWE measurements. Both groups did not have any evidence of hydronephrosis, renal calculus or distinct renal malignancies. After gaining consent, both groups underwent SWE as an extension to their routine diagnostic ultrasound examination of the upper abdomen or renal system. A brief medical questionnaire was completed by each volunteer. The bipolar renal length was recorded. The renal cortex elasticity values were measured with circular regions of interest placed in the upper, mid and lower zones of both kidneys and their corresponding Young's modulus (YM) SWE values measured in kilopascals (kPa) were recorded. Two sample unpaired t-tests was used to compare the measured renal stiffness SWE values (in kPa) between the normal control and CKD group. Results 40 participants were recruited, of those 20 had CKD and 20 control. The bipolar renal length was significantly reduced in CKD participants to 104mm ( ± 21mm) from control group of 111mm ( ± 11mm) (p = 0.03). The SWE values (in kPa) measuring the renal stiffness was significantly higher in the CKD group than those of normal controls (p Conclusion Participants with CKD had significantly higher (p