Shear wave elastography in chronic kidney disease: a pilot experience in native kidneys

Abstract

BackgroundThere currently is a need for a non-invasive measure of renal fibrosis. We aim to explore whether shear wave elastography (SWE)-derived estimates of tissue stiffness may serve as a non-invasive biomarker that can distinguish normal and abnormal renal parenchymal tissue.MethodsParticipants with CKD (by estimated GFR) and healthy volunteers underwent SWE. Renal elasticity was estimated as Young’s modulus (YM) in kilopascals (kPa). Univariate Wilcoxon rank-sum tests were used.ResultsTwenty-five participants with CKD (median GFR 38 mL/min; quartile 1, quartile 3 28, 42) and 20 healthy controls without CKD underwent SWE performed by a single radiologist. CKD was associated with increased median YM (9.40 [5.55, 22.35] vs. 4.40 [3.68, 5.70] kPa; p = 0.002) and higher median intra-subject inter-measurement estimated YM’s variability (4.27 [2.89, 9.90] vs. 1.51 [1.21, 2.05] kPa; p < 0.001).ConclusionsSWE-derived estimates of renal stiffness and intra-subject estimated stiffness variability are higher in patients with CKD than in healthy controls. Renal fibrosis is a plausible explanation for the observed difference in YM. Further studies are required to determine the relationship between YM, estimated renal stiffness, and renal fibrosis severity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-015-0120-7) contains supplementary material, which is available to authorized users.

Shear wave elastography imaging for assessing the chronic pathologic changes in advanced diabetic kidney disease

“…Of the few studies that examined the use of SWE to assess renal stiffness, and its relationship to native kidney function, four evaluated renal elasticity in CKD patients 8,38–40. Only two studies showed that SWE imaging, using ARFI-based technology, can be used to assess renal morphologic changes in patients with DKD 10,11.…”

Mechanotransduction Dynamics at the Cell-Matrix Interface

“…Previous studies have demonstrated that the elastic modulus of an underlying surface can modulate cell migration (5)(6)(7)(8), cell differentiation (9-13), cell spreading (14,15), and cell survival (16)(17)(18). Clinical studies have shown that tissue stiffness can have profound effects on disease progression: patients bearing malignant tumors with increased elastic modulus present with more severe disease (19,20); increased elastic modulus in liver tissue is a predictor of cirrhosis (21); and kidney tissue stiffness has been shown to correlate with disease progression in chronic kidney disease (22). Clearly, cells are able to sense the mechanical properties of their surroundings, and subsequent cell fate and function are determined by mechanically transduced signals.…”

Value of ultrasound elastography in the diagnosis of native kidney fibrosis.

“…Measurements taken so far have significant variations between studies, highlighting the necessity for extensive trials on healthy kidneys. For example, the elasticity values of renal cortex varies, upon different assessments, between 15.4±2.5 kPa [18] to 5.0±2.9 kPa [21] or even 4.40 (3.68, 5.70) kPa [32] for Young's modulus in SSI or SWEI, and between 1.75 m/s [25] to 2.54±0.83 m/s [27] for shear wave velocity in ARFI. The kidney region examined is important, as significant differences in elasticity have been reported between the outer and inner cortex [22], between the medullary and cortical portion of the kidney [18], and between the cortex and renal pelvis [21].…”

“…In the native kidney, human studies have reported various markers associated with increased kidney stiffness: estimated glomerular filtrate rate (eGFR) [23,28,29], urinary albumin / creatinine or protein / creatinine ratio [30,33], serum creatinine [23,29], urea nitrogen [23], elasticity values in healthy native kidneys [23][24][25][26][27][28][29][30][31][32][33]35], kidney biopsies [25], other imaging tests etc [24,26,35]. Thus, there are studies finding no significant correlation between markers of chronic kidney injury and elasticity of renal parenchyma in native [27] or transplanted kidney [48,51], and also studies which could not prove a significant difference of elasticity between different stages of CKD [23,25]; in addition, it has been reported an increased intra-subject variability of results in CKD versus healthy controls [33] or a higher influence of arteriosclerosis markers, such as pulsatility index or resistivity index, on kidney stiffness than eGFR [28].…”