Quantitative Assessment of Kidney Interstitial Fibrosis Using Optical Spectroscopy Mediated through a Fine Needle...

Area of Science:

• Nephrology
• Biomedical Optics
• Medical Diagnostics

Background:

• Quantitative assessment of renal fibrosis via biopsy is challenging due to time, variability, and sampling errors.
• Accurate fibrosis assessment is crucial for donor kidney evaluation, as ~20% of grafts are rejected due to assessment errors.
• Elastic Scattering Spectroscopy (ESS) offers a potential objective, rapid alternative for intrarenal fibrosis assessment.

Purpose of the Study:

• To investigate the accuracy of intrarenal Elastic Scattering Spectroscopy (ESS) for quantifying renal fibrosis.
• To compare ESS-based fibrosis assessment with the conventional interstitial fibrosis and tubular atrophy (IFTA) scoring.
• To evaluate the utility of ESS for point-of-care, multi-site kidney tissue evaluation.

Main Methods:

• A rat model of chronic kidney disease was used to acquire spectral data using a fine-needle ESS probe at three intrarenal depths.
• Linear regression and random forests (RFs) were employed to correlate ESS spectral features with histopathological IFTA scores.
• Continuous and categorical RF models were developed to predict fibrosis severity at different depths.

Main Results:

• RF regression demonstrated high accuracy in predicting fibrosis across different depths (R2 values up to 0.961 when averaged).
• Categorical RF models achieved high prediction accuracies, with an overall average of 98.61% after cross-validation.
• ESS measurements showed progressive fibrosis over 4 weeks in the rat model.

Conclusions:

• Intrarenal ESS provides a robust, depth-resolved, quantitative estimation of renal fibrosis, closely matching histological IFTA scoring.
• Multi-depth sampling with ESS enhances predictive accuracy by mitigating local fibrosis variability.
• ESS serves as an objective, rapid adjunct for point-of-care kidney tissue evaluation, potentially eliminating the need for biopsies.