Acoustic Radiation Force Impulse Elastography of the Kidneys

Abstract

Objectives The aim of this study was to identify the main influencing factor of the shear wave velocity (SWV) of the kidneys measured by acoustic radiation force impulse elastography. Methods The SWV was measured in the kidneys of 14 healthy volunteers and 319 patients with chronic kidney disease. The estimated glomerular filtration rate was calculated by the serum creatinine concentration and age. As an indicator of arteriosclerosis of large vessels, the brachial‐ankle pulse wave velocity was measured in 183 patients. Results Compared to the degree of interobserver and intraobserver deviation, a large variance of SWV values was observed in the kidneys of the patients with chronic kidney disease. Shear wave velocity values in the right and left kidneys of each patient correlated well, with high correlation coefficients (r = 0.580–0.732). The SWV decreased concurrently with a decline in the estimated glomerular filtration rate. A low SWV was obtained in patients with a high brachial‐ankle pulse wave velocity. Despite progression of renal fibrosis in the advanced stages of chronic kidney disease, these results were in contrast to findings for chronic liver disease, in which progression of hepatic fibrosis results in an increase in the SWV. Considering that a high brachial‐ankle pulse wave velocity represents the progression of arteriosclerosis in the large vessels, the reduction of elasticity succeeding diminution of blood flow was suspected to be the main influencing factor of the SWV in the kidneys. Conclusions This study indicates that diminution of blood flow may affect SWV values in the kidneys more than the progression of tissue fibrosis. Future studies for reducing data variance are needed for effective use of acoustic radiation force impulse elastography in patients with chronic kidney disease.

Kidney Shear Wave Speed Values in Subjects with and without Renal Pathology and Inter-Operator Reproducibility of Acoustic Radiation Force Impulse Elastography (ARFI) - Preliminary Results

“…This is an interesting finding, different from the results of liver elastography and in line with the recently published data by Guo et al [39] and also by our group [42] which evaluated the kidney shear wave speed by ARFI elastography in healthy volunteers and patients with different impairment of renal function. These data suggest that factors other than interstitial fibrosis have an important role in kidney shear wave speed measurements, one of them being renal blood flow [26].…”

“…[22]–[24] It is possible that kidney shear wave speed measured using ARFI elastography is influenced by renal blood flow as well. [25], [26].…”

Acoustic Radiation Force Impulse Imaging for Non-Invasive Assessment of Renal Histopathology in Chronic Kidney Disease

“…Some scholar speculated the differences of histological changes and mechanical property between kidney and liver result in this inconsistency [14] . Asano et al [26] reported the degree of interstitial fibrosis in the kidneys of CKD is not as marked as that in chronic liver disease and suspected interstitial fibrosis is not the main affecting factor of ARFI elastography in the kidneys tissue elasticity.…”

“…One explanation for these inconsistent results may be the relatively small number of patients in Wang et al's study. Another hypothesis was that the structural heterogeneity of renal parenchyma and the diminished renal blood flow impacted on the SWV values in patients with CKD [26] .…”

Ultrasound Elastography: Review of Techniques and Clinical Applications

“…The reason for this difference remains unclear. Asano et al hypothesized that the decreased renal blood flow in patients with CKD reduces kidney stiffness, resulting in decreased shear wave velocities 107.…”