Extracellular Volume Fraction Imaging for Hepatic Fibrosis: CT and MRI Implementation and Evidence.

Accurate diagnosis and staging of liver fibrosis are essential for prognostic stratification and treatment planning in chronic liver disease. However, conventional approaches for diagnosing and monitoring fibrosis, such as biopsy, elastography and serum-based scores, are limited by invasiveness, sampling variability, or performance in early-stage disease. Extracellular volume fraction (ECV) has emerged as a promising non-invasive quantitative imaging biomarker for assessing extracellular space expansion associated with hepatic fibrotic remodeling. In this review, we summarize current preclinical and clinical data on computed tomography (CT-) and magnetic resonance imaging (MRI)-derived ECV in liver fibrosis and related chronic liver diseases, with a focus on calculation methods, biologic interpretation, and correlations with histopathology and selected clinical outcomes. We also discuss major sources of heterogeneity, key interpretive limitations, and the evidence gaps that must be addressed before hepatic ECV can be more broadly integrated as a complementary component of multiparametric liver imaging.