Diagnostic accuracy of ADC values as a supplementary tool in differentiating hepatocellular adenoma from focal nodular hyperplasia: a systematic review and meta-analysis

Background Accurate differentiation between hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH) is essential due to divergent management and risk profiles. Diffusion-weighted MRI (DWI) with apparent diffusion coefficient (ADC) quantification has been proposed as a non-contrast method to distinguish these lesions. Methods A systematic search of PubMed, Embase, Web of Science, and Cochrane Library was performed through August 2025 following PRISMA-DTA guidelines. Studies comparing ADC values in HCA and FNH, reporting measurements for at least five lesions per group, were included. Quality assessment used the QUADAS-2 tool. Random-effects meta-analysis pooled mean ADC values, calculated standardized mean differences (SMD), and assessed heterogeneity (I²). Sensitivity analyses, subgroup analyses by study design, and publication bias evaluation using trim-and-fill were conducted. Results Thirteen studies comprising 524 lesions (195 HCA, 329 FNH) met inclusion criteria. Pooled mean ADC was 1.44×10⁻³ mm²/s (95% CI: 1.34–1.55) for FNH and 1.35×10⁻³ mm²/s (95% CI: 1.23–1.47) for HCA, yielding an absolute difference of 0.10×10⁻³ mm²/s (p = 0.073) and SMD of 0.49 (95% CI: − 0.02–0.99). Relative ADC difference was 7.6% (p = 0.109). Heterogeneity was high (I² = 84.5%). Prospective studies showed reduced heterogeneity (I² = 0%) but non-significant mean difference (0.21×10⁻³ mm²/s). Trim-and-fill attenuated effect size further, confirming non-significance. Conclusion ADC values exhibit only modest, non-significant differences between HCA and FNH, with substantial heterogeneity limiting clinical applicability. Standardized, prospective multicenter studies and multiparametric MRI protocols remain necessary to improve non-contrast differentiation of these lesions.