Renal elastography in kidney disease: Current evidence, limitations, and future directions

Abstract

Renal elastography has gained attention as a noninvasive way to estimate tissue stiffness and, indirectly, structural kidney damage. In general, elastography is considered a noninvasive test (NIT) for assessing liver fibrosis, and it has been widely adopted and even proposed as a potential alternative to liver biopsy in selected settings. However, its use as an NIT has not been completely translated to the kidney, largely due to fundamental differences in tissue structure and hemodynamics. Unlike the relatively homogeneous liver, the kidney is anisotropic and highly dependent on perfusion. Therefore, stiffness measurements may be affected by blood flow, vascular resistance, and interstitial pressure at the time of measurement, making them more difficult to interpret. There is growing evidence that shear-wave elastography can detect structural changes in chronic kidney disease, hypertension-related damage, acute kidney injury, and some glomerular disorders. That said, findings remain inconsistent. The reported cut-off values vary widely between studies, and reproducibility remains limited. Technical factors, such as inter-device and acquisition-protocol variability, further complicate the comparison of imaging results. In practice, elastography provides information about tissue mechanics and may be complementary to conventional imaging and laboratory markers. However, it might not be specific if used alone. Combined approaches of specifically shear-wave elastography with functional and biochemical NIT could provide better diagnostic performance and reflect a more clinically useful approach. Overall, renal elastography is better viewed as a complementary tool rather than a replacement for histology. Future research should focus on standardization, improving cross-platform validation, and generating longitudinal data to clarify its role in clinical decision-making and risk assessment.

Keywords: Shear-wave elastography; Kidney diseases; Cortical stiffness; Kidney biopsy; Serum biomarkers

Core Tip: Renal elastography is a non-invasive tool for assessing tissue stiffness and may help detect structural kidney injury earlier than traditional blood and imaging markers. But unlike the liver, kidney stiffness is greatly affected by perfusion and hemodynamic variables, making interpretation difficult. Currently, the evidence is heterogeneous, and there are no defined thresholds that limit its use as a single diagnostic tool. Elastography should preferably be combined with clinical, functional, and imaging data in a multimodal approach to improve the non-invasive assessment of kidney disease.