Real-time elastography in the assessment of liver fibrosis: a review of qualitative and semi-quantitative methods for elastogram analysis.

Despite its invasiveness, liver biopsy is still considered the gold standard for the assessment of hepatic fibrosis. Non-invasive ultrasound-based techniques are increasingly employed to assess parenchymal stiffness and the progression of chronic diffuse liver diseases. Real-time elastography is a rapidly evolving technique that can reveal the elastic properties of tissues. This review examines qualitative and semi-quantitative methods developed for analysis of real-time liver elastograms, to estimate parenchymal stiffness and, indirectly, the stage of fibrosis. Qualitative analysis is the most immediate approach for elastogram analysis, but this method increases intra- and inter-observer variability, which is seen as a major limitation of real-time elastography. Semi-quantitative methods include analysis of the histogram derived from color-coded maps, as well as calculation of the elastic ratio and fibrosis index.