Characterizing Viscoelastic Polyvinyl Alcohol Phantoms for Ultrasound Elastography

Sharma, Ananya; Marapureddy, Sai Geetha; Paul, Abhijit; Bisht, Sapna R.; Kakkar, Manik; Thareja, Prachi; Mercado-Shekhar, Karla P.

doi:10.1016/j.ultrasmedbio.2022.09.019

Cited by 11 publications

(18 citation statements)

References 41 publications

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“…To assess the effect of the cryoprotectant on the acoustic and mechanical properties of the phantoms, samples without the cryoprotectant were fabricated, comprising 8% w/v PVA (Elvanol 71–30, Kuraray America, Inc., Houston, USA), silicon carbide (SiC) acoustic scatterers (2% w/v, 600 mesh, Sarrah, India), and 90% v/v degassed, deionized water. , Samples with the cryoprotectant were made with the same concentration of PVA and SiC, except with 70% v/v degassed, deionized water and 20% v/v ethylene glycol-based cryoprotectant liquid (antifreeze coolant, Waxpol Industries Ltd., Ranchi, India).…”

Section: Methodsmentioning

confidence: 99%

“…The frequency-dependent attenuation spectra of the phantoms α( f ) were calculated as α ( f ) = 10 log 10 ( false| V ref ( f ) false| 2 false| V phantom ( f ) false| 2 ) / 2 h where f is the frequency and V ref and V phantom are the amplitudes of the reflected ultrasound signals without and with the phantom, respectively. The attenuation coefficient (dB/cm) was calculated by power-law regression . Longitudinal sound speeds and attenuation coefficients were measured from five independent locations in each phantom sample and five independent samples per phantom type.…”

Section: Methodsmentioning

confidence: 99%

“…A Butterworth bandpass filter (10–800 Hz) and a median filter (3λ × 3λ kernel) were applied to smoothen the particle velocity data. ,, Next, a 2D fast Fourier transform (FFT) of the shear wavefronts was performed, and the phase velocity (dispersion) curve was generated. To estimate the shear modulus and viscosity of each phantom, the phase velocity curve was fit to the Kelvin–Voigt (KV) model using least-squares nonlinear curve fitting based on the trust-region reflective algorithm. ,, Assuming a homogeneous, isotropic medium and the planar nature of shear waves within the ROI, the phase velocity ( c s ) based on the KV model is expressed as follows: c s ( f ) = 2 false( G 2 + false( 2 π f false) 2 η 2 false) ρ true( G + ( G 2 + ( 2 π f ) 2 η 2 ) true) where G is the shear modulus, ρ is the density, f is the frequency, and η is the viscosity. Shear modulus and viscosity estimates were obtained for five independent imaging planes of each phantom sample and five samples of each phantom type.…”

Section: Methodsmentioning

confidence: 99%

“…Density, Longitudinal Sound Speed, and Acoustic Attenuation Measurements. The density of the phantoms was measured based on the volume and mass of the phantoms, which were determined by the water-displacement method 15 and a precision weighing balance (SAB-220, Precision Electronic, Rachana Weightech, Ahmedabad, Gujarat, India), respectively.…”

Section: Cryoprotectant-based Pva Phantom Fabricationmentioning

confidence: 99%

“…To estimate the shear modulus and viscosity of each phantom, the phase velocity curve was fit to the Kelvin−Voigt (KV) model using leastsquares nonlinear curve fitting based on the trust-region reflective algorithm. 15,25,26 Assuming a homogeneous, isotropic medium and the planar nature of shear waves within the ROI, the phase velocity (c s ) based on the KV model is expressed as follows: 27…”

Section: Cryoprotectant-based Pva Phantom Fabricationmentioning

confidence: 99%

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Viscoelastic Characterization of Phantoms for Ultrasound Elastography Created Using Low- and High-Viscosity Poly(vinyl alcohol) with Ethylene Glycol as the Cryoprotectant

Bisht,

Marri,

Karmakar

et al. 2024

ACS Omega

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Ultrasound elastography enables noninvasive characterization of the tissue mechanical properties. Phantoms are widely used in ultrasound elastography for developing, testing, and validating imaging techniques. Creating phantoms with a range of viscoelastic properties relevant to human organs and pathological conditions remains an active area of research. Poly(vinyl alcohol) (PVA) cryogel phantoms offer a long shelf life, robustness, and convenient handling and storage. The goal of this study was to develop tunable phantoms using PVA with a clinically relevant range of viscoelastic properties. We combined low-and high-viscosity PVA to tune the viscoelastic properties of the phantom. Further, phantoms were created with an ethylene glycol-based cryoprotectant to determine whether it reduces the variability in the viscoelastic properties. Scanning electron microscopy (SEM) was performed to evaluate the differences in microstructure between phantoms. The density, longitudinal sound speed, and acoustic attenuation spectra (5−20 MHz) of the phantoms were measured. The phantoms were characterized using a shear wave viscoelastography approach assuming the Kelvin−Voigt model. Microstructural differences were revealed by SEM between phantoms with and without a cryoprotectant and with different PVA mixtures. The longitudinal sound speed and attenuation power-law fit exponent of the phantoms were within the clinical range (1510−1571 m/s and 1.23−1.38, respectively). The measured shear modulus (G) ranged from 3.3 to 17.7 kPa, and the viscosity (η) ranged from 2.6 to 7.3 Pa•s. The phantoms with the cryoprotectant were more homogeneous and had lower shear modulus and viscosity (G = 2.17 ± 0.2 kPa; η = 2.0 ± 0.05 Pa•s) than those without a cryoprotectant (G = 3.93 ± 0.7 kPa; η = 2.6 ± 0.14 Pa•s). Notably, phantoms with relatively constant viscosities and varying shear moduli were achieved by this method. These findings advance the development of well-characterized viscoelastic phantoms for use in elastography.

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Section: Methodsmentioning

confidence: 99%