Viscosity Imaging for Detection of Liver Inflammation: A Systematic Review

Background: Chronic liver disease affects millions globally, with inflammation being a critical indicator of disease progression. Current diagnostic methods have limitations in detecting early-stage liver inflammation, delaying intervention and worsening outcomes. Objective: To review evidence on viscosity imaging as a non-invasive technique for detecting liver inflammation, including diagnostic accuracy and comparative effectiveness versus existing methods. Methods: A systematic search of PubMed, Embase, Web of Science, and Cochrane Library was conducted from inception to January 2025. Studies evaluating viscosity imaging for liver inflammation detection were included. Two reviewers screened articles, extracted data, and assessed quality using QUADAS-2. Primary outcomes were diagnostic accuracy and correlation with histological inflammation grades. Results: Of 2,847 records, 45 studies met criteria, comprising 8,234 patients. Viscosity imaging showed sensitivity of 78% (95% CI: 74-82%) and specificity of 76% (95% CI: 72-80%) for moderate-to-severe inflammation. Viscosity parameters correlated with inflammation grades (r=0.48-0.52, p<0.001) independent of fibrosis. In NAFLD/NASH, viscosity imaging achieved higher accuracy (AUROC 0.82) versus elastography (AUROC 0.69, p=0.02). MRE showed superior reproducibility (ICC 0.90-0.96) versus ultrasound methods (ICC 0.82-0.91). Viscosity parameters decreased faster than stiffness after treatment. Conclusion: Viscosity imaging demonstrates moderate-to-good diagnostic accuracy for liver inflammation detection. Combined with elastography, it enables comprehensive liver assessment and supports earlier intervention. Further prospective studies with long-term data are needed to establish clinical utility.