Assessment of renal tissue elasticity by acoustic radiation force impulse quantification with histopathological correlation: preliminary experience in chronic kidney disease.

OBJECTIVES: Chronic kidney disease (CKD), a progressive and irreversible pathological syndrome, is the major cause of renal failure. Renal fibrosis is the principal process underlying the progression of CKD. Acoustic radiation force impulse (ARFI) quantification is a promising noninvasive method for assessing tissue stiffness. We evaluated whether the technique could reveal renal tissue fibrosis in CKD patients.
METHODS: ARFI assessments were performed in 45 patients with CKD referred for renal biopsies to measure cortical shear wave velocity (SWV). During measurement, a standardized method was employed, which aimed to minimize the potential impact of variation of transducer force, sampling error of non-cortical tissue and structural anisotropy of the kidney. Then SWV was compared to patients' CKD stage and pathological fibrosis indicators.
RESULTS: ARFI could not predict the different stages of CKD. Spearman correlation analysis showed that SWV did not correlate with any pathological indicators of fibrosis.
CONCLUSION: ARFI assesses tissue stiffness of CKD kidneys by measuring cortical SWV. However, SWV did not show significant correlations with CKD stage and fibrosis indicators despite using standardized measurement methods. We therefore suggest that it would be necessary to evaluate the effect of pathological complexity and tissue perfusion of the kidney on stiffness assessment in future studies. KEY POINTS: • Acoustic radiation force impulse (ARFI) can quantify tissue elasticity of CKD kidney. • Despite standardized measurement, ARFI-estimated elasticity did not correlate with renal fibrosis. • Effects of pathological complexity and tissue perfusion on renal stiffness warrant further study.