scholarly journals Fundamental modeling of wave propagation in temporally relaxing media with applications to cardiac shear wave elastography

2020 ◽  
Vol 147 (5) ◽  
pp. 3091-3099
Author(s):  
A. Sabbadini ◽  
L. B. H. Keijzer ◽  
H. J. Vos ◽  
N. de Jong ◽  
M. D. Verweij
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Shear Wave Elastography

scholarly journals Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongliang Li ◽  
Guillaume Flé ◽  
Manish Bhatt ◽  
Zhen Qu ◽  
Sajad Ghazavi ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Soft Tissues ◽  
Acoustic Radiation ◽  
Single Cells ◽  
Shear Waves ◽  
Mechanical Vibration ◽  
Shear Wave Elastography ◽  
Biomechanical Properties ◽  
Biological Tissues

Changes in biomechanical properties of biological soft tissues are often associated with physiological dysfunctions. Since biological soft tissues are hydrated, viscoelasticity is likely suitable to represent its solid-like behavior using elasticity and fluid-like behavior using viscosity. Shear wave elastography is a non-invasive imaging technology invented for clinical applications that has shown promise to characterize various tissue viscoelasticity. It is based on measuring and analyzing velocities and attenuations of propagated shear waves. In this review, principles and technical developments of shear wave elastography for viscoelasticity characterization from organ to cellular levels are presented, and different imaging modalities used to track shear wave propagation are described. At a macroscopic scale, techniques for inducing shear waves using an external mechanical vibration, an acoustic radiation pressure or a Lorentz force are reviewed along with imaging approaches proposed to track shear wave propagation, namely ultrasound, magnetic resonance, optical, and photoacoustic means. Then, approaches for theoretical modeling and tracking of shear waves are detailed. Following it, some examples of applications to characterize the viscoelasticity of various organs are given. At a microscopic scale, a novel cellular shear wave elastography method using an external vibration and optical microscopy is illustrated. Finally, current limitations and future directions in shear wave elastography are presented.

scholarly journals Reverberant Shear Wave Elastography: A Multi-Modal and Multi-Scale Approach to Measure the Viscoelasticity Properties of Soft Tissues

2021 ◽  
Vol 8 ◽  
Author(s):  
Juvenal Ormachea ◽  
Fernando Zvietcovich
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Acoustic Waves ◽  
Guided Waves ◽  
Soft Tissues ◽  
Ex Vivo ◽  
Surface Acoustic Waves ◽  
Shear Wave Elastography ◽  
Biomechanical Properties

There are a variety of approaches used to create elastography images. Techniques based on shear wave propagation have received significant attention. However, there remain some limitations and problems due to shear wave reflections, limited penetration in highly viscous media, requirements for prior knowledge of wave propagation direction, and complicated propagation in layers where surface acoustic waves and guided waves are dominant. To overcome these issues, reverberant shear wave elastography (RSWE) was proposed as an alternative method which applies the concept of a narrow-band diffuse field of shear waves within the tissue. Since 2017, the RSWE approach has been implemented in ultrasound (US) and optical coherence tomography (OCT). Specifically, this approach has been implemented in these imaging modalities because they are similar in image formation principles and both share several approaches to estimate the biomechanical properties in tissues. Moreover, they cover different spatial-scale and penetration depth characteristics. RSWE has shown promising results in the elastic and viscoelastic characterization of multiple tissues including liver, cornea, and breast. This review summarizes the 4-year progress of the RSWE method in US and OCT. Theoretical derivations, numerical simulations, and applications in ex vivo and in vivo tissues are shown. Finally, we emphasize the current challenges of RSWE in terms of excitation methods and estimation of biomechanical parameters for tissue-specific cases and discuss future pathways for the in vivo and in situ clinical implementations.

Liver Elastography in Healthy Children Using Three Different Systems – How Many Measurements Are Necessary?

2020 ◽  
Author(s):  
Anders Batman Mjelle ◽  
Anesa Mulabecirovic ◽  
Roald Flesland Havre ◽  
Edda Jonina Olafsdottir ◽  
Odd Helge Gilja ◽  
...  
Keyword(s):  
Shear Wave ◽  
Transient Elastography ◽  
Intraclass Correlation ◽  
Age Groups ◽  
Liver Stiffness ◽  
Shear Wave Elastography ◽  
Healthy Children ◽  
Significant Difference ◽  
Pediatric Liver Disease ◽  
Liver Elastography

Abstract Purpose Liver elastography is increasingly being applied in screening for and follow-up of pediatric liver disease, and has been shown to correlate well with fibrosis staging through liver biopsy. Because time is of the essence when examining children, we wanted to evaluate if a reliable result can be achieved with fewer acquisitions. Materials and Methods 243 healthy children aged 4–17 years were examined after three hours of fasting. Participants were divided into four age groups: 4–7 years; 8–11 years; 12–14 years and 15–17 years. Both two-dimensional shear wave elastography (2D-SWE; GE Logiq E9) and point shear wave elastography (pSWE; Samsung RS80A with Prestige) were performed in all participants, while transient elastography (TE, Fibroscan) was performed in a subset of 87 children aged 8–17 years. Median liver stiffness measurement (LSM) values of 3, 4, 5, 6, 7, and 8 acquisitions were compared with the median value of 10 acquisitions (reference standard). Comparison was performed for all participants together as well as within every specific age group. We investigated both the intraclass correlation coefficient (ICC) with absolute agreement and all outliers more than 10 %, 20 % or ≥ 0.5 or 1.0 kPa from the median of 10 acquisitions. Results For all three systems there was no significant difference between three and ten acquisitions, with ICCs ≥ 0.97. All systems needed 4 acquisitions to achieve no LSM deviating ≥ 1.0 kPa of a median of ten. To achieve no LSM deviating ≥ 20 % of a median of ten acquisitions, pSWE and TE needed 4 acquisitions, while 2D-SWE required 6 acquisitions. Conclusion Our results contradict recommendations of 10 acquisitions for pSWE and TE and only 3 for 2D-SWE.

Diagnotic value of Shear Wave Elastography in differentiating parathyroid adenomas from thyroid nodules

2019 ◽  
Author(s):  
Mihaela Vlad ◽  
Ioana Golu ◽  
Maria Oprea ◽  
Daniela Amzar ◽  
Melania Balas ◽  
...  
Keyword(s):  
Shear Wave ◽  
Thyroid Nodules ◽  
Shear Wave Elastography ◽  
Parathyroid Adenomas
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