Introduction: ARFI elastography is very useful for liver stiffness assessment, but few information are available regarding
kidney stiffness (KS), especially in non-transplanted kidneys where a standardized examination technique is not available.
Aim:to identify the best place where KS measurements by means of ARFI elastography should be performed.
Methods:Our study included 20 healthy volunteers with a mean age of 24.4±1.5 years: subjects
without known kidney pathology, with normal renal ultrasonography, without history of renal disease (supplementary investigations were not performed). KS measurements by means of ARFI elastography were performed in supine position, lateral decubitus and prone position in each kidney. For each of these positions, KS was measured in the mid-portion of renal parenchyma, in the superior and inferior pole. We aimed for 5 valid measurements in each position and then median values were calculated and
expressed in meters/second (m/s).
Results:Five valid ARFI elastographic measurements were obtained in supine position in mid portion, inferior and superior pole in 85%, 85% and 20% of cases in right kidney and 95%, 90% and 15% in left kidney. In lateral decubitus, five valid measurements were obtained in mid portion, inferior and superior pole in 100%, 90% and 30% of cases in right kidney and 100%, 95% and 60% in
left kidney. In prone position, five valid measurements were obtained in mid portion, inferior and superior pole in 95%, 90% and 60% of cases in right kidney and 100%, 90% and 60% in left kidney. Mean KS values (m/s) obtained in lateral and prone position (the positions with the best feasibility) were similar for the right kidney: 2.42±0.56 vs. 2.47±0.89, p=0.94 and also for the left kidney: 2.43±0.74 vs. 2.51±0.60, p=0.75.
Conclusion:KS measurements should be performed in mid portion of renal parenchyma, in lateral decubitus or prone position, according to the patient’s acoustic window.
