Mapping kidney tubule diameter ex vivo by diffusion MRI

Area of Science:

• Nephrology
• Biophysics
• Medical Imaging

Background:

• Kidney disease frequently involves tubular pathologies.
• Current kidney health assessments rely on invasive biopsies or indirect biomarkers.
• Noninvasive tools for measuring tubular pathology are needed.

Purpose of the Study:

• To evaluate diffusion MRI (dMRI) as a noninvasive tool for measuring kidney tubular lumen size ex vivo.
• To demonstrate dMRI's sensitivity to water diffusion at the scale of kidney tubules.
• To assess dMRI's potential as a biomarker for tubular pathology.

Main Methods:

• Monte Carlo simulations to confirm dMRI sensitivity to restricted diffusion.
• Application of dMRI and biophysical modeling to ex vivo kidneys (mouse, rat, human).
• Biophysical model based on superposition of free and cylinder-restricted water diffusion.

Main Results:

• dMRI accurately measured tubular diameters, within 10% of histological measurements.
• dMRI detected altered tubular distribution in a mouse model of acute kidney injury.
• Simulations confirmed dMRI's sensitivity to diffusion at the tubule scale.

Conclusions:

• dMRI can quantify tubular diameter distribution in ex vivo kidney cortex.
• dMRI shows promise as a novel, noninvasive biomarker for kidney tubular pathology.
• This technique may improve the assessment of kidney health and disease.