Abstract
BACKGROUND: Chronic liver disease (CLD) is a major global health burden, and accurate assessment of hepatic function is crucial for prognosis and management. Conventional biochemical scores, including Child-Pugh, MELD-Na, ALBI, and FIB-4, provide valuable information but lack spatial insight into parenchymal dysfunction. Gadoxetic acid–enhanced MRI during the hepatobiliary phase (HBP) offers functional evaluation, yet existing indices focus primarily on parenchymal enhancement without accounting for vascular contrast retention. This study aimed to develop and internally evaluate a novel MRI-derived Severity Index that integrates both vascular and parenchymal signal dynamics to provide a comprehensive, noninvasive evaluation of hepatic functional reserve. METHODS: In this retrospective study, 193 participants (122 CLD patients, 71 controls) undergoing HBP MRI were evaluated. Signal intensities from the liver, aorta, and portal vein were measured, and a novel Severity Index was calculated as (Aorta SI × Portal Vein SI) / Liver SI. Patients were stratified into compensated, decompensated, and subclinical groups based on clinical and laboratory criteria (ALBI, MELD-Na, Child-Pugh, FIB-4). Diagnostic performance, correlations with established scores, and reproducibility were analyzed using nonparametric tests, ROC curves, regression models, and intraclass correlation coefficients (ICC). RESULTS: The Severity Index was significantly higher in CLD patients compared with controls (p < 0.001) and in decompensated versus compensated patients (p < 0.001). ROC analysis demonstrated excellent discrimination between compensated and decompensated CLD (AUC = 0.848, cut-off ≥ 162.6, sensitivity 80.9%, specificity 70.7). Subclinical patients also showed higher index values than controls (p < 0.001), with good discriminatory performance (AUC = 0.811, cut-off ≥ 105.9, sensitivity 93%, specificity 64.8). The Severity Index correlated with MELD-Na (r = 0.504, p < 0.001) and ALBI (r = 0.389, p < 0.001). Interobserver agreement was excellent (ICC = 0.927). CONCLUSION: The Severity Index is a novel, reproducible MRI-derived biomarker that integrates vascular and parenchymal dynamics to assess hepatic reserve. It reliably distinguishes disease stages, correlates with established scores, and identifies subclinical dysfunction, supporting its potential role in early diagnosis and risk stratification in CLD.