Establishing the Effective Frequency of Canon Ultrasound Shear Wave Dispersion Slope Measurements in Viscoelastic Models to Determine Liver Viscosity

Background Assessing phase velocities in ultrasound elastography imaging could provide useful diagnostic information about viscoelastic properties of liver tissue, which may be a marker for liver disease. The only clinically approved ultrasound system for measuring phase velocities provides a single value, the SWD 'Slope' (SWDS). However, to compare different imaging systems, it is important to verify the ultrasound frequency at which the 'Slope' is being calculated. With this information, it would be possible to measure liver viscosity values. In this phantom study, we aim to establish the effective frequency of the SWDS by comparing experimentally measured values to theoretical viscoelastic models of phantom

Methods Three certified phantoms with known phase velocities were obtained from CIRS, Inc., VA, USA. Experimental SWDS measurements were obtained using an i8CX1 probe on an Aplio i800 ultrasound system (Canon Medical Systems Corp., Japan). 18 ROIs per phantom were placed 1 to 2 cm below the surface and averaged to produce measured SWDS values. The Voigt, Maxwell, Zener, Fractional Zener, and Jeffreys models were assessed; for each model, the best fit was determined in MATLAB 2024b by minimizing the error between measured and model values.

Results The Jeffreys model showed the lowest root mean squared error for modeling the certified data. The effective frequencies at which tangents to the Jeffreys model curves are most accurate are at 27.76 Hz, 28.53 Hz, and 28.72 Hz for the three phantoms (average of 28.34 Hz).

Conclusion We show that the Jeffreys model most accurately captures the phase velocity curve of phantoms, and that the effective frequency at which the SWDS is calculated is 28 Hz. This frequency is lower than expected for ultrasound, indicating that the manufacturer is performing some modeling to shift the frequency range prior to displaying the SWDS value. The identified effective frequency may be used in the future to generate viscosity values of liver tissue following SWDS measurements.

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Artikel online veröffentlicht:
16. Oktober 2025