Derivation and analysis of viscoelastic properties in human liver: impact of frequency on fibrosis and steatosis staging

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 62; no. 1; pp. 165 - 175
• Main Authors: Nightingale, Kathryn R., Rouze, Ned C., Rosenzweig, Stephen J., Wang, Michael H., Abdelmalek, Manal F., Guy, Cynthia D., Palmeri, Mark L.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.01.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustics; Algorithms; Analytical models; Correlation analysis; Data models; Direct current; Dispersion; Dispersions; Elasticity - physiology; Elasticity Imaging Techniques - methods; Fatty Liver - diagnostic imaging; Fatty Liver - physiopathology; Fibrosis; Finite Element Analysis; Frequency measurement; Humans; Image Processing, Computer-Assisted; Liver; Liver - diagnostic imaging; Liver - physiology; Liver cirrhosis; Liver Cirrhosis - diagnostic imaging; Liver Cirrhosis - physiopathology; Materials; Mathematical models; Medical research; ROC Curve; Sound waves; Viscoelasticity
• ISSN: 0885-3010; 1525-8955; 1525-8955
• DOI: 10.1109/TUFFC.2014.006653

Commercially-available shear wave imaging systems measure group shear wave speed (SWS) and often report stiffness parameters applying purely elastic material models. Soft tissues, however, are viscoelastic, and higher-order material models are necessary to characterize the dispersion associated with broadband shear waves. In this paper, we describe a robust, model-based algorithm and use a linear dispersion model to perform shear wave dispersion analysis in traditionally difficult-to-image subjects. In a cohort of 135 non-alcoholic fatty liver disease patients, we compare the performance of group SWS with dispersion analysis-derived phase velocity c(200 Hz) and dispersion slope dc/df parameters to stage hepatic fibrosis and steatosis. Area under the ROC curve (AUROC) analysis demonstrates correlation between all parameters [group SWS, c(200 Hz), and, to a lesser extent dc/df ] and fibrosis stage, whereas no correlation was observed between steatosis stage and any of the material parameters. Interestingly, optimal AUROC threshold SWS values separating advanced liver fibrosis (≥F3) from mild-to-moderate fibrosis (≤F2) were shown to be frequency-dependent, and to increase from 1.8 to 3.3 m/s over the 0 to 400 Hz shear wave frequency range.