Kidney cortex shear wave motion simulations based on segmented biopsy histology.

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Computational Biology

Background:

• Kidney transplant biopsies are invasive and limit frequent monitoring.
• Shear wave elastography (SWE) offers a non-invasive alternative for assessing kidney allograft health.
• Understanding microstructural changes' impact on SWE is crucial for transplant management.

Purpose of the Study:

• To evaluate the relationship between microstructural variations in kidney allografts and alterations in SWE measurements.
• To investigate the mechanical property changes associated with chronic allograft rejection using computational modeling.

Main Methods:

• Simulated heterogeneous shear wave motion in segmented kidney cortex using the staggered-grid finite difference (SGFD) method.
• Isolated and analyzed mechanical properties of glomeruli, tubules, interstitium, and fluid.
• Measured shear wave velocity dispersion and estimated rheological parameters (elasticity and viscosity) using the generalized Stockwell transform and Kelvin-Voigt model.

Main Results:

• Inflammation led to significant changes in interstitial and glomerular areas, increasing elasticity and viscosity.
• Mild tubular atrophy correlated with elevated group velocity and elasticity (µ1).
• Mild to moderate fibrosis showed negligible alterations in SWE parameters, indicating limited morphological impact.

Conclusions:

• The developed computational model can simulate patient-specific kidney cortex properties.
• Pathological changes in cortical morphology demonstrably correlate with modifications in SWE-derived rheological measurements.
• Inflammation significantly impacts measured mechanical properties, validating SWE's potential in transplant monitoring.