The application of shear wave quantitative ultrasound elastography in chronic kidney disease

Chronic kidney disease (CKD) is a major public health problem, so it is particularly important to quantitatively assess and intervene in the degree of early renal damage in CKD.

The objective of the research is to establish reference values for kidney elasticity by using real-time shear wave elastography (RT-SWE) technology to quantify Young's modulus values in the renal cortex of normal adults. The intention is to provide a foundation for evaluating renal function and structural changes in patients with CKD. Furthermore, this research investigates the role of RT-SWE in the early detection of renal fibrosis in CKD, providing insights into its diagnostic value for detecting pathological changes at an early stage.

Between August 2019 and December 2021, we collected a sample of 100 healthy people (55 men with an average age of 43.5 ± 15.2 years and 45 women with an average age of 41.6 ± 19.8 years) for medical evaluations at our hospital's Department of Ultrasound Medicine. In addition, 97 individuals with CKD1-3 stage were considered. Following the removal of contraindications and relevant confounding variables, we included a final cohort of 80 individuals in the research (45 men and 35 females, with an average age of 39.1 ± 19.2 years). The RENAL mode was selected and a convex array probe S6-1 operating at a frequency of 3.5-5.5 MHz was used in the research, which made use of the French Supersonic AixPlorer ultrasonic diagnostic instrument. Renal RT-SWE elastography was performed after conventional two-dimensional and color Doppler ultrasonography. The study used RT-SWE technology to assess the mean Young's modulus of the cortex in healthy individuals (Emean), with data analysis and comparisons based on age and gender. Furthermore, the Emean values of CKD stage 1-3 patients were determined, and analyses were performed about 24-hour urine protein quantitative (24hUTP), serum creatinine concentration (SCr), and renal biopsy pathology, specifically the degree of interstitial fibrosis.

Healthy group: a) The average kPa values of the left kidney (4.2 ± 2.3), right kidney (4.3 + 2.5) kPa, both kidneys' average kPa values (4.3 ± 2.4) kPa, and the average kPa values of the left and right kidneys do not differ statistically (p= 0.986). b) There was no difference in the kPa values of healthy male and female kidneys (4.4 + 2.1 and 4.2 + 2.6, respectively. c) There was no difference in the renal kPa values of healthy adults aged 50 (4.4 ± 2.8) kPa and renal kPa of the 50-year-old population (4.2 + 2.1) kPa (p= 0.041). Case group: a) the group of patients with CKD1-3 stage and the group did not vary in their Emean values (both p< 0.05); b) There is a difference between CKD stages 1, 2, and 3 (p< 0.05), however, there is still no difference in the pyEmean value corrected for patient age between patients in stages 1 and 2 (p> 0.05).

The study reveals no significant differences in the Emean value of bilateral kidneys in normal people and no differences in the elasticity value of kidneys and gender. However, age-based differences were statistically significant. pyEmean may be useful for comparing CKD stage 1, 2, and 3 patients, and RT-SWE can assess early renal damage.