Quantification of Kidney Fibrosis Using Ultrasonic Shear Wave Elastography

Abstract

Objectives The purpose of this study was to evaluate the feasibility of ultrasonic shear wave elastography for quantification of renal fibrosis in an experimental rabbit model. Methods Thirty‐eight kidneys of 19 rabbits were studied and categorized into 3 groups: group I, ureter obstruction (n = 9); group II, renal vein occlusion (n = 10); and group III, normal control (n = 19). Before surgery, we measured stiffness at the renal cortex using shear wave elastography and evaluated the sonographic findings, including size, echogenicity, and resistive index. We repeated the same sonographic examinations weekly until the fourth week. The degree of histologically quantified fibrosis and the measured stiffness values were statistically compared. Results There was no significant difference in the mean stiffness values for the renal cortex in the 3 groups before surgery (8.95 kPa in group I, 9.06 kPa in group II, and 9.74 kPa in group III; P > .05). However, the mean stiffness in each group on the last sonographic examination was significantly different (10.91 kPa in group I, 13.92 kPa in group II, and 9.77 kPa in group III; P = .003). Pathologically, the degree of fibrosis was also significantly different (3.62% in group I, 11.70% in group II, and 0.70% in group III; P< .001). The fibrosis degree and stiffness were positively correlated (ρ = 0.568; P = 0.01). Conclusions Tissue stiffness measured by ultrasonic shear wave elastography was positively correlated with histopathologic renal fibrosis. Ultrasonic shear wave elastography may be used as a noninvasive tool for predicting renal fibrosis.

A Two-Criterion Model for Microvascular Bio-Effects Induced In Vivo by Contrast Microbubbles Exposed to Medical Ultrasound

“…The values of the density ( ρ ), interfacial tension ( σ ), rigidity ( G ) and viscosity ( µ ) for blood were 1050 kg m −3 , 0.056 N m −1 , 0.0 kPa and either 3 or 5 mPa·s, respectively, while those for kidney tissue were 1100 kg m −3 , 0.056 N m −1 , either 0 kPa, 1 kPa, 2 kPa or 0.18 MPa and 3 – 23 mPa·s, respectively. These values encompass bulk-tissue values for rigidity reported for kidney from ultrasound elastography methods for frequencies below 1 kHz (Arda et al 2011; Amador et al 2011;Derieppe et al 2012; Gennisson et al 2012; Grenier et al 2013; Moon et al 2015) and a direct shear-wave method for frequencies above 6 MHz (Yang and Church 2006). It is worth noting here that in all cases for which sufficient data are available for comparison over several orders of magnitude for frequency, the values for the modulus of rigidity in tissue tend to remain the same, while values for viscosity decrease by a factor of 100 (see also Madsen et al 1983; Deffieux et al 2009; Chen et al 2013).…”

“…Also shown are the results of Miller et al (2008b) for experimental thresholds of GCH for the LAB exposure system (squares) and the DUS system (diamonds, open symbols show the “no-effect” level at the highest outputs available); the straight lines are the best fits through the positive results for the two systems. The dashed line labeled MI =1.9 represents the upper limit on the MI for diagnostic scanners approved under the FDA’s track 3 process.…”

“…6 to the equation p t = bf a . The solid lines are the best fits to the experimental results of Miller et al (2008b), labeled in plot 7a. See the caption to Fig.…”

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

“…Consequently, the earliest studies of renal SWE imaging were performed in animals and transplanted kidneys. Animal studies on rats and rabbits showed a direct correlation between renal cortical stiffness and renal fibrotic changes, and between an increase in cortical stiffness and a decline in renal function 19,20. In studies of transplanted kidneys, increased renal stiffness was detected in cases of transplant rejection and in patients who developed acute deterioration in renal function 21–37…”

A two-criterion model for microvascular bioeffects induced in vivo by contrast microbubbles exposed to medical ultrasound

“…The values of the density (ρ), interfacial tension (σ), rigidity (G) and viscosity (µ) for blood were 1050 kg m −3 , 0.056 N m −1 , 0.0 kPa and either 3 or 5 mPa·s, respectively, while those for kidney tissue were 1100 kg m −3 , 0.056 N m −1 , either 0 kPa, 1 kPa, 2 kPa or 0.18 MPa and 3 -23 mPa·s, respectively. These values encompass bulk-tissue values for rigidity reported for kidney from ultrasound elastography methods for frequencies below 1 kHz (Arda et al 2011;Amador et al 2011;Derieppe et al 2012;Gennisson et al 2012;Grenier et al 2013;Moon et al 2015) and a direct shear-wave method for frequencies above 6 MHz . It is worth noting here that in all cases for which sufficient data are available for comparison over several orders of magnitude for frequency, the values for the modulus of rigidity in tissue tend to remain the same, while values for viscosity decrease by a factor of 100 (see also Madsen et al 1983;Deffieux et al 2009;Chen et al 2013).…”