New insights on the role of anisotropy in renal ultrasonic elastography: From trash to treasure

Chronic kidney disease (CKD) is a progressive and irreversible pathological syndrome that starts silently, continues through renal dysfunction and ends up in renal failure. Currently there is a critical need to develop non-invasive imaging biomarkers for the identification of early renal damage and the assessment of renal pathological alterations. Anisotropy is the intrinsic property of the architecture of renal parenchyma, which is responsible for the variation of measurement between different orientations on ultrasonic elastography (USE). Based on this correlation, we hypothesize that USE may quantify the degree of parenchymal anisotropy of kidney with the orientation-derived variation of measurement. In order to standardize the variation, a novel USE biomarker is proposed, the anisotropic ratio (AR), which is the ratio of elasticity of renal parenchyma achieved with the transducer aligned along versus across the nephrons. If this hypothesis could be proved, AR may enable the detection of pathological changes in the parenchymal structure of kidney. Then, AR would be used in the management of disease in CKD patients, and serve as a diagnostic and monitoring biomarker.