Renal R2* as a noninvasive predictor of hepatorenal syndrome-acute kidney disease in cirrhotic patients with ascites: a retrospective cohort study

Abstract

Background: Hepatorenal syndrome-acute kidney disease (HRS-AKD) is associated with poor renal outcomes in cirrhotic patients, yet no established noninvasive imaging marker exists for its early prediction. This study evaluated renal R2* derived from magnetic resonance elastography (MRE) with multi-echo R2* mapping as a noninvasive imaging marker for predicting the development of HRS-AKD in cirrhotic patients with ascites. Methods: This retrospective observational study analyzed 376 patients who underwent liver MRE with multi-echo R2* mapping between January 2018 and October 2024. Median renal R2* values were quantified from the left kidney using radiomics-based analysis. HRS-AKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2) or a >= 50% increase in serum creatinine from baseline within 3 months after MRE, without other causes of renal disease. Diagnostic performance of renal R2* was compared with liver stiffness and serum fibrosis markers, including the aspartate aminotransferase-to-alanine aminotransferase ratio (AAR), aspartate aminotransferase-to-platelet ratio index (APRI), and fibrosis-4 (FIB-4) index. Multivariable logistic regression identified independent predictors of HRS-AKD. Results: Among cirrhotic patients with ascites, 12.9% developed HRS-AKD; 62.5% had a prior episode of HRS-acute kidney injury (AKI). Median renal R2* was higher in patients who developed HRS-AKD (P=0.007), and inversely correlated with eGFR measured at MRE (r=-0.34, P=0.006). Renal R2* did not correlate with serum iron markers or hemoglobin (all P >= 0.05). The area under the receiver operating characteristic curve (AUROC) of renal R2* was 74.5 [95% confidence interval (CI): 57.4-91.6] for predicting HRS-AKD, outperforming liver stiffness and serum fibrosis markers. An R2* cut-off of 20.8 s(-1) yielded 75% sensitivity and 74% specificity. R2* >= 20.8 s(-1) was an independent predictor of HRS-AKD [odds ratio (OR) 16.8; P=0.002]. Conclusions: Renal R2* is a promising noninvasive imaging marker candidate for predicting the development of HRS-AKD in cirrhotic patients with ascites.