Association between Kidney Allograft Fibrosis and Magnetic Resonance Elastography-Derived Stiffness in Kidney Transplant Recipients

Background: Kidney biopsy remains the gold standard for assessing fibrosis. However, it is an invasive procedure and leads to significant complications. Magnetic resonance elastography (MRE) has been evaluated as an alternative method for evaluating fibrosis, but the results are still inconclusive. Herein, we aimed to determine the association between MRE-derived whole stiffness and interstitial fibrosis and tubular atrophy and urinary transforming growth factor (TGF) beta. Methods: We conducted a cross-sectional study involving adult kidney transplant patients who required kidney biopsy. Enrolled patients underwent evaluation using two-dimensional gradient-echo MRE within 2 days prior to biopsy, enabling the determination of MRE-derived whole kidney stiffness through computer-assisted techniques. Urinary TGF beta was collected at the biopsy date and measured by ELISA. Pathological results were classified according to the Banff classification system. Correlations between MRE-derived whole kidney stiffness, histologic fibrosis, and urinary TGF beta were analyze. Results: 21 patients were calculated for interim analysis. Majority were deceased donor kidney transplant patients (90.5%). Median transplant vintage was 8.6 years (interquartile range [IQR] 3.8-11.1 years) with a median estimated glomerular filtration rate of 36.6 ml/min/1.73 m2 ([IQR] 24.3-49.6 ml/min/1.73 m2). Most common biopsy indication was allograft dysfunction. We found that mean MRE-derived whole kidney stiffness was a significant negative correlation to the overall nephron fibrosis and ct scores (Rho = -0.48, p=0.03, Rho = -0.47, p=0.03, respectively). In addition, there was a trend to negatively associate ci and cv scores and whole kidney stiffness. However, MRE-derived kidney stiffness did not show a significant correlation with urine TGF beta. Conclusion: MRE-derived whole kidney stiffness correlates with nephron fibrosis, suggesting that MRE could offer a promising alternative for fibrosis evaluation in kidney transplant recipients. Funding: Government Support – Non-U.S.