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

Abstract

Aimto assess the inter-operator reproducibility of kidney shear wave speed, evaluated by means of Acoustic Radiation Force Impulse (ARFI) elastography, and the factors which influence it.MethodsOur prospective pilot study included 107 subjects with or without kidney pathology in which kidney shear wave speed was evaluated by means of ARFI elastography. Intraclass correlation coefficient (ICC) was used to assess ARFI elastography reproducibility.ResultsA strong agreement was obtained between kidney shear wave speed measurements obtained by the two operators: ICC = 0.71 (right kidney) and 0.69 (left kidney). Smaller ICCs were obtained in “healthy subjects”, as compared to patients with kidney diseases (0.68 vs. 0.75), in women as compared with men (0.59 vs. 0.78), in subjects younger than 50 years as compared with those aged at least 50 years (0.63 vs. 0.71), in obese as compared with normal weight and overweight subjects (0.36 vs. 0.66 and 0.78) and in case of measurements depth <4 cm or >6 cm as compared with those performed at a depth of 4–6 cm from the skin (0.32 and 0.60 vs. 0.81).ConclusionARFI elastography is a reproducible method for kidney shear wave speed assessment.

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

“…Inter-observer agreement is reported in various studies at different ICC (intra-class coefficients correlation), from 0.71 [27] to 0.47 [47] or even 0.31 [48], being smaller than those for the assessment of liver fibrosis [49,50]. These variations are explained by the deeper location of the native kidney compared to the liver, by the different experience of the operators in the field of renal US elastography, or may be due to the type of kidney examined, native or transplanted [27].…”

“…These variations are explained by the deeper location of the native kidney compared to the liver, by the different experience of the operators in the field of renal US elastography, or may be due to the type of kidney examined, native or transplanted [27]. Intra-observer variation coefficients are also reported between 20% [51] and 24% [48].…”

“…linear increase of renal tissue elasticity associated with elevated urinary pressure [22,26]. Gender [21,34], race [27], weight or body mass index (BMI) [20], and also age [23,34,46] can modify the results in US elastography and several studies have found significant variations of renal parenchymal elasticity in these parameters [20,21,23,27,34,46].…”

Point shear wave elastography (pSWE) using Acoustic Radiation Force Impulse (ARFI) imaging: a feasibility study and norm values for renal parenchymal stiffness in healthy children and adolescents

“…The ICC was 0.81. A study in adult kidneys with and without pathology revealed an inter-observer agreement assessed by ICC of 0.68 for healthy and 0.75 for pathologic kidneys [33]. Likewise, Hu et al reported a good inter-observer agreement for adult kidneys with chronic kidney disease of 0.63 [14].…”

“…Results showed lower mean SWS values and less measurement variability by using the 4-9 MHz ultrasound probe [32]. A better feasibility of the 4-9 MHz transducer in smaller children was observed due to a smaller ROI [33]. Canas et al compared a 1-4 MHz probe and a 4-9 MHz probe by measuring the tissue elasticity of spleens in healthy children.…”