#4624 viscoelasticity measurement- a new ultrasound-based elastography method in the assessment of the kidney

Abstract Background and Aims Viscoelasticity is the result of the tissue's combined viscous and elastic response to stress. This characteristic can reveal details about the function of the kidney and is essential for comprehending how it responds to deformation. Hologic Aixplorer Mach 30 ultrasound system comes with new and improved software that indirectly assesses the viscosity of the renal tissue by measuring tissue shear wave dispersion. Method Over the course of 2022 we performed a cross-sectional study by including 50 healthy participants, 50 kidney-transplanted patients, and 40 patients with chronic glomerulonephritis (before being referred for renal biopsy). Viscosity plane-wave ultrasound (Vi PLUS) measurements were performed on each participant, and the mean value of five distinct evaluations for each kidney was correlated with their demographic, biological, and clinical parameters. Results The mean viscosity value for the healthy group was 2.44 ± 0.57 Pascal.second (Pa.s), correlated with age (r = -0.4251, p = 0.0021), estimated glomerular filtration rate (eGFR) (r = 0.4057, p = 0.0038) but it did not correlate with C reactive protein (CRP), the mean value for Vi PLUS in the kidney-transplanted group was 2.82± 0.59 Pa.s, correlated with eGFR (r = 0.3335, p = 0.0180), but not with age or CRP, and the mean value for the patients with chronic glomerulonephritis group was 2.39 ± 0.73 Pa.s, did not correlate with age, but correlated with eGFR (r = 0.3637, p < 0.0211) and CRP (r = -0.3695, P = 0.0189) and we also found for a cut-off value of <2.8 Pa.s for detecting the presence of tubulointerstitial fibrosis with an AUC of 0.792, p < 0.001 with 94% sensitivity, and 60% specificity. Results of one-way ANOVA (p = 0.001), used to test the differences in the variables among the three groups, showed statistically significant higher values for the viscoelasticity in renal transplant patients compared to the other two groups, but no differences between the healthy and chronic glomerulonephritis groups. Conclusion Our results show that this novel ultrasound technique correlates with renal function and inflammation (in chronic glomerulonephritis patients) and it is also capable of discriminating between patients with and without tubulointerstitial fibrosis, but further research is needed for it to be implemented into routine clinical practice.