scholarly journals Effect of Ultrafast Imaging on Shear Wave Visualization and Characterization: An Experimental and Computational Study in a Pediatric Ventricular Model

2017 ◽  
Vol 7 (8) ◽  
pp. 840 ◽  
Author(s):  
Annette Caenen ◽  
Mathieu Pernot ◽  
Ingvild Kinn Ekroll ◽  
Darya Shcherbakova ◽  
Luc Mertens ◽  
...  
Keyword(s):  
Shear Wave ◽  
Computational Study ◽  
Ultrafast Imaging

scholarly journals Experimental Evidence of Generation and Reception by a Transluminal Axisymmetric Shear Wave Elastography Prototype

Diagnostics ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 645
Author(s):  
Antonio Gomez ◽  
Manuel Hurtado ◽  
Antonio Callejas ◽  
Jorge Torres ◽  
Nader Saffari ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Shear Wave ◽  
Shear Wave Elastography ◽  
Sensing Element ◽  
New Approach ◽  
Shear Wave Speed ◽  
Ultrafast Imaging ◽  
Axisymmetric Shear ◽  
Rotational Actuator ◽  
Good Agreement

Experimental evidence on testing a non-ultrasonic-based probe for a new approach in transluminal elastography was presented. The proposed modality generated shear waves by inducing oscillatory rotation on the lumen wall. Detection of the propagated waves was achieved at a set of receivers in mechanical contact with the lumen wall. The excitation element of the probe was an electromagnetic rotational actuator whilst the sensing element was comprised by a uniform anglewise arrangement of four piezoelectric receivers. The prototype was tested in two soft-tissue-mimicking phantoms that contained lumenlike conduits and stiffer inclusions. The shear wave speed of the different components of the phantoms was characterized using shear wave elastography. These values were used to estimate the time-of-flight of the expected reflections. Ultrafast ultrasound imaging, based on Loupas’ algorithm, was used to estimate the displacement field in transversal planes to the lumenlike conduit and to compare against the readouts from the transluminal transmission–reception tests. Experimental observations between ultrafast imaging and the transluminal probe were in good agreement, and reflections due to the stiffer inclusions were detected by the transluminal probe. The obtained experimental evidence provided proof-of-concept for the transluminal elastography probe and encouraged further exploration of clinical applications.

Influence of Tissue Microstructure on Shear Wave Speed Measurements in Plane Shear Wave Elastography: A Computational Study in Lossless Fibrotic Liver Media

2017 ◽  
Vol 40 (1) ◽  
pp. 49-63 ◽  
Author(s):  
Yu Wang ◽  
Jingfeng Jiang
Keyword(s):  
Shear Wave ◽  
Wave Speed ◽  
Computational Study ◽  
Shear Wave Elastography ◽  
Biological Tissues ◽  
Plane Shear ◽  
Frequency Dependent ◽  
Fibrotic Liver ◽  
Shear Wave Speed ◽  
Liver Tissues

Shear wave elastography (SWE) has been used to measure viscoelastic properties for characterization of fibrotic livers. In this technique, external mechanical vibrations or acoustic radiation forces are first transmitted to the tissue being imaged to induce shear waves. Ultrasonically measured displacement/velocity is then utilized to obtain elastographic measurements related to shear wave propagation. Using an open-source wave simulator, k-Wave, we conducted a case study of the relationship between plane shear wave measurements and the microstructure of fibrotic liver tissues. Particularly, three different virtual tissue models (i.e., a histology-based model, a statistics-based model, and a simple inclusion model) were used to represent underlying microstructures of fibrotic liver tissues. We found underlying microstructures affected the estimated mean group shear wave speed (SWS) under the plane shear wave assumption by as much as 56%. Also, the elastic shear wave scattering resulted in frequency-dependent attenuation coefficients and introduced changes in the estimated group SWS. Similarly, the slope of group SWS changes with respect to the excitation frequency differed as much as 78% among three models investigated. This new finding may motivate further studies examining how elastic scattering may contribute to frequency-dependent shear wave dispersion and attenuation in biological tissues.

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.

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