[Quantitative imaging in nephrology: limits and potentials of elastosonography]

Chronic kidney disease is characterized by increasingly amplified fibrotic processes regardless of etiology. The severity of renal fibrosis seems to correlate with an increased risk of end-stage renal disease; therefore, monitoring of renal fibrosis over time may play an important role in the follow-up of both focal and diffuse renal diseases and in evaluating the response to treatments. Renal biopsy is the only method capable of providing objective and comparable information on the extent of fibrosis, but it is not suitable for outpatient monitoring of chronic kidney disease due to its invasiveness. Elastosonography is an innovative and non-invasive ultrasound method that allows the measurement of tissue elasticity through the transmission of mechanical waves and the measurement of their propagation speed. Although some authors have demonstrated the usefulness of elastosonographic techniques for the quantification of liver fibrosis, few studies have investigated the applications of elastosonography in renal pathology. Furthermore, the depth of native kidneys, the high anisotropy of the renal tissue, and the possibility of examining only a small region of interest currently limit its spread in clinical practice. The aim of this review is to examine the physical principles of elastosonography and to review the latest evidence about the possible applications of the ARFI (acoustic radiation force impulse) technique in the study of kidney diseases.