Investigating liver stiffness and viscosity for fibrosis, steatosis and activity staging using shear wave elastography

Abstract

Quantitative shear wave elastography was shown to be an effective tool for the non-invasive diagnosis and staging of chronic liver diseases. The liver shear modulus, estimated from the propagation velocity of shear waves, is correlated to the degree of fibrosis and can therefore be used for the non-invasive staging of fibrosis. We performed a clinical prospective study in a total of 120 patients with various chronic liver diseases to compare the accuracy of supersonic shear imaging (SSI), a technique based on acoustic radiation and ultrafast ultrasound imaging, to 1D transient elastography (FibroScan) for the staging and grading of fibrosis as assessed by liver biopsy. Since shear wave propagation spectroscopy can also provide additional mechanical information on soft tissues, such as viscosity, we also investigated those new mechanical parameters as possible predictors of fibrosis, steatosis, and disease activity. SSI was successfully performed in 98.3% of patients and it was shown to be as accurate as FibroScan for the staging of fibrosis both for the whole population (N=120) and for the subgroup with viral hepatitis (n=70) (AUC=0.85 [0.77-0.96] and 0.89 [0.81-0.97] for significant fibrosis, AUC=0.90 [0.83-0.97] and 0.87 [0.75-0.98] for cirrhosis, with respect to SSI [n=68/70] and FibroScan [n=66/68]). Viscosity could also be used to stage the degree of fibrosis (AUC=0.76 [0.64-0.87] for significant fibrosis and AUC=0.87 [0.74-0.99] for cirrhosis), for the subgroup of patients with viral hepatitis (n=67/70) but was a poor predictor of disease activity and steatosis levels. Supersonic shear imaging is a robust technique for the staging of liver fibrosis. Liver viscosity was found to be correlated with fibrosis but not to steatosis or disease activity.