The comparison of resistivity index and strain index values in the ultrasonographic evaluation of chronic kidney disease

Abstract

Objectives: Chronic kidney disease (CKD) is a disorder progressing to end-stage kidney failure. Early diagnosis and treatment are important for medical care. The aim of this prospective study was to define the strain index (SI) and resistivity index (RI) values in the same CKD group for each kidney separately at the same time, and also to compare the efficacy of SI and RI in the differentiation of normal population and CKD patients.

Materials and methods: Toshiba Aplio 500 USG device and 3.5-5 MHz convex probe were used for USG, CDUSG, and USG elastography examinations. The patients were referred to radiology clinique from nephrology and endocrinology cliniques after GFR calculation. Patients with renal cyst, tumor, or obstructive renal disease were excluded. Healthy volunteers according to laboratory and clinical examinations were selected from non-kidney disease patients.

Results: A total of 121 CKD (68 men, 53 women) and 40 healthy volunteers (19 men, 21 women) were participated. The mean SI and RI values of CKD were significantly higher than the normal healthy volunteers (p < 0.05). The SI and RI values of right and left kidney did not show any difference in CKD patients (p values were 0.381 for SI and 0.821 for RI). The sensitivity and the specificity of the SI were higher than RI.

Conclusion: The RI and SI values of kidneys in CKD patients were significantly higher than those of apparently normal kidneys. SI was more sensitive than RI in our study. Determining cut-off SI and RI values between normal and damaged renal parenchyma can help in the diagnosis and follow up of CKD patients.

Advances in knowledge: To the best of our knowledge, this is the first study comparing RI and SI in CKD patients, and SI is found to be more sensitive than RI for the evaluation of CKD.

Keywords: Chronic kidney disease; Elastography; Resistivity Index; Strain Index; Ultrasonography.