Introduction Non-invasive assessment of liver fibrosis with elastography is increasingly used as the sole diagnostic method to assess patients with HCV infection for suitability for new anti-viral therapies. Currently patients with cirrhosis form the majority of those funded for some oral treatments in England. A large proportion reside in London and the South East region. As shear velocity cut offs for Metavir F4 fibrosis with the ARFI technique (virtual touch quantification, VTq™) are based upon historical studies, which may have been subject to sources of bias, there is a need for disease specific, population adjusted data. We report the results of a biopsy controlled study from two centres, designed to investigate optimal ARFI cut-offs for determining cirrhosis in our population.
Methods Our database of 96 patients with HCV infection obtained from two centres was interrogated. ARFI shear velocity (SV) estimation was performed with 10 right lobe measurements. Fibrosis stage was confirmed in 84 by right lobe liver biopsy within 2 hours of ARFI, and cirrhosis was confirmed by B-mode US imaging criteria in the remaining 12. Ultrasonic and histopathological data was collated retrospectively. Diagnostic performance of ARFI was determined by ROC analysis, using a) reference SV cut-off values for Metavir stage, and b) optimal SV thresholds for cirrhosis derived from our local data, including subgroup analysis.
Results Three subgroups were analysed: 1) all 96 cases, including 20 patients with co-pathology (HBV, NAFLD, or ALD); 2) 76 cases with HCV only; 3) 84 cases who had simultaneous biopsy. Cirrhosis was present in 26, 20 and 14, respectively. Predictive accuracy for Metavir F4 using the reference threshold of 1.75 m/sec was 90%, 92% and 88% in groups 1, 2 and 3, respectively. Using new thresholds and ARFI mean SVs required a higher cutoff of 1.99 in group 1 compared with 1.64 in groups 2 and 3 to achieve accuracies of 87%–93%, whereas more consistent performance across all groups was achieved with median SVs at a cutoff of 1.89, achieving accuracies of 93%, 96% and 92%, respectively.
Conclusion These “real world” data confirm the high predictive accuracy of ARFI for Metavir F4 cirrhosis in our local HCV cohort. Optimal performance was seen for median SV cutoff of 1.89 m/sec. However, adjustment of diagnostic thresholds may be necessary when making treatment decisions for less selected populations and in those patients with co-existent pathology.
Disclosure of Interest None Declared