The association between renal elasticity evaluated by Real-time tissue elastography and renal fibrosis

The progression of chronic kidney disease (CKD) depends on the extent of fibrosis in the kidneys; however, a renal biopsy is necessary to evaluate the severity of renal fibrosis. Real-time tissue elastography (RTE), which measures heartbeat-induced tissue displacement, can assess the elasticity of organs. Here, we aimed to investigate the correlation between renal elasticity and the extent of fibrosis in renal biopsy samples.

We investigated 29 consecutive patients who underwent a renal biopsy at Ehime University Hospital from February 2018 to August 2019. Renal fibrosis was categorized into three grades, mild (< 25%), moderate (25-50%), and severe (> 50%), based on the total affected area within the biopsy sample. The association between renal elasticity assessed by RTE and the grade of renal fibrosis was evaluated, and a receiver operating characteristic curve was used to distinguish the severity of renal fibrosis.

The mean age and estimated glomerular filtration rate (eGFR) were 58.8 years and 55.2 mL/min/1.73 m², respectively. The median urine protein-to-creatinine ratio was 1.24 g/gCr. The mean renal elasticity of mild, moderate, and severe renal fibrosis was 3.40, 3.98, and 4.77, respectively. Renal elasticity of native kidneys was significantly positively correlated with the grade of renal fibrosis (ρ = 0.529, P = 0.003). At the cutoff point of 3.81, the area under the curve, sensitivity, and specificity were 0.778, 68.4%, and 81.8%, respectively.

Real-time tissue elastography is a promising, non-invasive method for assessing renal fibrosis in patients with CKD.