Acute renal impairment characterization using diffusion magnetic resonance imaging: Validation by histology

Area of Science:

• Nephrology
• Radiology
• Biomedical Engineering

Background:

• Diffusion magnetic resonance imaging (dMRI) is a noninvasive technique for evaluating renal microstructure and microcirculation, crucial for kidney function.
• Serum endothelin-1 (ET-1) is recognized as a potential biomarker for early renal injury.
• Ureteroscopic lithotripsy often involves high-pressure renal pelvic perfusion, which can lead to acute kidney injury (AKI).

Purpose of the Study:

• To assess the feasibility and capability of diffusion MRI and serum ET-1 in detecting AKI induced by simulated high-pressure renal pelvic perfusion.
• To compare the diagnostic performance of dMRI parameters with serum ET-1 levels and histological findings.

Main Methods:

• Fourteen New Zealand rabbits underwent a procedure simulating high-pressure renal pelvic perfusion (experimental group), with 14 serving as controls.
• Diffusion tensor imaging (DTI) and intravoxel incoherent motion (IVIM) dMRI were performed using a 3.0 T MRI scanner.
• Serum ET-1 levels and renal histology were analyzed, with histology serving as the reference standard.

Main Results:

• Significant differences in apparent diffusion coefficient (ADC), pure tissue diffusion, pseudo-diffusion fraction (fp), and fractional anisotropy (FA) were observed between renal cortex and medulla in the experimental group.
• Post-procedure, the experimental group showed significant decreases in cortical fp_mean, medullary ADC_mean, and FA_mean compared to controls (P < 0.05).
• Serum ET-1 levels did not change significantly in either group, while histological examination revealed medullary changes in the experimental group.

Conclusions:

• Diffusion MRI is feasible for detecting microstructural and microcirculatory alterations in AKI, indicating its potential for evaluating renal function.
• dMRI demonstrates superior sensitivity to AKI compared to serum ET-1 levels.
• The study highlights dMRI's utility in identifying renal changes post-procedure, particularly in the medulla.