Published September 23, 2025
| Version v1
Dataset
Open
Enhanced shear wave attenuation estimation with expanded bandwidth in viscoelastic media
Authors/Creators
- 1. AGH University of Krakow
- 2. AGH Univeristy of Krakow
Description
Ultrasound shear wave elastography (SWE) is widely employed to differentiate healthy from pathological tissues based on their viscoelastic mechanical properties. Although elasticity has traditionally been the main focus, tissue viscosity also plays a crucial role in characterizing mechanical behavior using SWE. Numerous methods have been developed for estimating the viscosity, with rheological model-based approaches being the most widely used. However, model-free techniques are gaining increasing attention, as they do not impose a predetermined relationship between wave velocity and attenuation, offering greater flexibility in capturing complex tissue viscoelastic behavior. In this study, we propose a novel method for calculating the shear wave attenuation. The approach, termed SAGA-ST, integrates a Super-Gaussian window-based Stockwell transform with slant frequency–wavenumber (f-k) analysis and leverages the full width at half-maximum of the f-k spectrum. The SAGA-ST method was first evaluated using analytical phantom data in tissue-mimicking viscoelastic media. To further assess its robustness, we applied the method to analytical shear wave motion data corrupted with varying levels of additive white Gaussian noise. Experimental validation was also performed using data from custom-designed tissue-mimicking phantoms and ex vivo bovine liver sample. We compared the performance of SAGA-ST with two existing techniques: the two-dimensional Fourier transform (2D-FT) and the generalized Stockwell transform-based method (GST-SFK). The proposed SAGA-ST method consistently demonstrates superior performance in analytical phantoms, exhibiting lower median attenuation bias and a smaller interquartile range. This is further supported by data points predominantly falling within the acceptable bias region and a median attenuation bias of less than 1% across all signal-to-noise ratio levels and frequency ranges, collectively indicating enhanced accuracy and precision. Furthermore, SAGA-ST extends the usable bandwidth for attenuation estimation, compared to the 2D-FT-based method, offering improved accuracy for tissue characterization.
Notes
Data acquisition:
Analytical data:
An analytical expression of particle velocity shear wave motion data was used to generate phantoms of viscoelastic materials with known mechanical properties following [1]. three different viscoelastic media with the material properties listed in table below.
| Parameter | PA1 | PA2 | PA3 |
|---|---|---|---|
| mu_1 [kPa] | 2 | 4 | 8 |
| mu_2 [kPa] | 8 | 16 | 35 |
| eta [Pa.s] | 1.2 | 4 | 2 |
Tissue-Mimicking Viscoelastic Phantoms:
- Three custom-made viscoelastic TM phantoms (SUN NUCLEAR/CIRS, Inc., Norfolk, VA, USA, manufactured in 2023) were used to determine shear wave attenuation with accompanying shear wave phase velocity estimations, using the SAGA-ST method.
- For each phantom, 10 acquisitions were performed with a physical rotation of the phantom between acquisitions.
- Shear wave data were acquired using a us4R-lite system equipped with 64RX and 256TX channels (us4us, Inc., Warsaw, Poland) and a linear array transducer (AT5L40B, Broadsound Corporation, Taiwan).
- The ARF push beams were generated using a total of 56 active elements, with a focal point at a depth of 15 mm (f# of 0.9).
- The duration and frequency of the ARF push were 400 us and 5.2 MHz.
- The ARF push was generated at four distinct voltage levels: 55, 45, 35, and 25 V, respectively.
- The detection pulses had voltages higher by 2 V compared to the push beams.
- A plane wave acquisition, using one plane wave was used (no angle compounding was applied).
- With an effective frame rate of 12.98 kHz, shear wave particle velocity motion data was derived from the in-phase/quadrature (IQ) data utilizing an autocorrelation algorithm.
- The particle velocity signals were averaged over a 3.1 mm axial range, centered at the focal depth.
Ex vivo Bovine Liver Data:
- Shear wave data from one ex vivo bovine liver - measured at two different spatial locations - were also used to investigate the robustness of the SAGA-ST method.
- The acquisition and processing protocols were consistent with those established for the TM viscoelastic phantoms
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The ARF push beam was generated using 64 active elements compared to the 56 elements used for the TM phantoms.
[1] Rouze, Ned C., Mark L. Palmeri, and Kathryn R. Nightingale. "An analytic, Fourier domain description of shear wave propagation in a viscoelastic medium using asymmetric Gaussian sources." The Journal of the Acoustical Society of America 138.2 (2015): 1012-1022.
Files
Analytical data.zip
Additional details
Related works
- Is published in
- Journal: 10.1016/j.compbiomed.2025.111042 (DOI)
Funding
- National Science Centre
- Novel extended frequency shear wave elastography for the evaluation of nearly incompressible viscoelastic materials UMO−2021/43/D/ST8/01295
Software
- Programming language
- MATLAB