scholarly journals MR elastography of the human heart: Noninvasive assessment of myocardial elasticity changes by shear wave amplitude variations

2008 ◽  
Vol 61 (3) ◽  
pp. 668-677 ◽  
Author(s):  
Ingolf Sack ◽  
Jens Rump ◽  
Thomas Elgeti ◽  
Abbas Samani ◽  
Jürgen Braun
Keyword(s):  
Shear Wave ◽  
Human Heart ◽  
Wave Amplitude ◽  
Mr Elastography ◽  
Noninvasive Assessment ◽  
Myocardial Elasticity

scholarly journals Absolute stress measurement of structural steel members with ultrasonic shear-wave spectral analysis method

2017 ◽  
Vol 18 (1) ◽  
pp. 216-231 ◽  
Author(s):  
Zuohua Li ◽  
Jingbo He ◽  
Jun Teng ◽  
Qin Huang ◽  
Ying Wang
Keyword(s):  
Spectral Analysis ◽  
Structural Steel ◽  
Shear Wave ◽  
Wave Amplitude ◽  
Stress Measurement ◽  
Amplitude Spectrum ◽  
Uniaxial Stress ◽  
Wave Pulse ◽  
Steel Members ◽  
Pulse Echo

Absolute stress in structural steel members is an important parameter for the design, construction, and servicing of steel structures. However, it is difficult to measure via traditional approaches to structural health monitoring. The ultrasonic time-of-flight method has been widely studied for monitoring absolute stress by measuring the change in ultrasonic propagation time induced by stress. The time-of-flight of the two separated shear-wave modes induced by birefringence, which is particular to shear waves, is also affected by stress to different degrees. Their synthesis signal amplitude spectrum exhibits a minimum that varies with stress, which makes it a potential approach to evaluating uniaxial stress using the shear-wave amplitude spectrum. In this study, the effect of steel-member stress on the shear-wave amplitude spectrum from the interference of two shear waves produced by birefringence is investigated, and a method of uniaxial absolute stress measurement using shear-wave spectral analysis is proposed. Specifically, a theoretical expression is derived for the shear-wave pulse-echo amplitude spectrum, leading to a formula for evaluating uniaxial absolute stress. Three steel-member specimens are employed to investigate the influence of uniaxial stress on the shear-wave pulse-echo amplitude spectrum. The testing results indicate that the amplitude spectrum changes with stress and that the inverse of the first characteristic frequency in the amplitude spectrum and its corresponding stress exhibit a near-perfect linear relationship. On this basis, the uniaxial absolute stress of steel members loaded by a test machine is measured by the proposed method. Parametric studies are further performed on three groups of steel members made of 65# steel and Q235 steel to investigate the factors that influence the testing results. The results show that the proposed method can measure and monitor steel-members uniaxial absolute stress on the laboratory scale and has potential to be used in practical engineering with specific calibration.

scholarly journals Noninvasive assessment and risk factors of liver fibrosis in patients with thalassemia major using shear wave elastography

Hematology ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 183-188 ◽  
Author(s):  
Murtadha Al-Khabori ◽  
Shahina Daar ◽  
Said A. Al-Busafi ◽  
Humoud Al-Dhuhli ◽  
AlGhalya A. Alumairi ◽  
...  
Keyword(s):  
Risk Factors ◽  
Liver Fibrosis ◽  
Shear Wave ◽  
Shear Wave Elastography ◽  
Thalassemia Major ◽  
Noninvasive Assessment

Measurement of Ultrasonic Shear Wave Amplitude Using Raman-Nath Parameter

1987 ◽  
Vol 26 (S1) ◽  
pp. 247
Author(s):  
Hiroki Kojoh ◽  
Kazuo Arakawa ◽  
Kiyoshi Takahashi ◽  
Satoshi Nagai
Keyword(s):  
Shear Wave ◽  
Wave Amplitude ◽  
Ultrasonic Shear

MR elastography, T1 and T2 relaxometry of liver: role in noninvasive assessment of liver function and portal hypertension

2020 ◽  
Vol 45 (9) ◽  
pp. 2680-2687 ◽  
Author(s):  
David H. Hoffman ◽  
Abimbola Ayoola ◽  
Dominik Nickel ◽  
Fei Han ◽  
Hersh Chandarana ◽  
...  
Keyword(s):  
Portal Hypertension ◽  
Liver Function ◽  
Mr Elastography ◽  
T2 Relaxometry ◽  
Noninvasive Assessment ◽  
T1 And T2

scholarly journals Development of an intravascular ultrasound elastography based on a dual-element transducer

2018 ◽  
Vol 5 (4) ◽  
pp. 180138 ◽  
Author(s):  
Cho-Chiang Shih ◽  
Pei-Yu Chen ◽  
Teng Ma ◽  
Qifa Zhou ◽  
K. Kirk Shung ◽  
...  
Keyword(s):  
Shear Wave ◽  
Intravascular Ultrasound ◽  
Elastic Properties ◽  
Wave Velocity ◽  
Wave Amplitude ◽  
Ex Vivo ◽  
Ultrasound Elastography ◽  
Elasticity Imaging ◽  
Dual Frequency ◽  
Peak Displacement

The ability to measure the elastic properties of plaques and vessels would be useful in clinical diagnoses, particularly for detecting a vulnerable plaque. This study demonstrates the feasibility of the combination of intravascular ultrasound (IVUS) and acoustic radiation force elasticity imaging for detecting the distribution of stiffness within atherosclerotic arteries ex vivo . A dual-frequency IVUS transducer with two elements was used to induce the propagation of the shear wave (by the 8.5 MHz pushing element) which could be simultaneously monitored by the 31 MHz imaging element. The wave-amplitude image and the wave-velocity image were reconstructed by measuring the peak displacement and wave velocity of shear wave propagation, respectively. System performance was verified using gelatin phantoms. The phantom results demonstrate that the stiffness differences of shear modulus of 1.6 kPa can be distinguished through the wave-amplitude and wave-velocity images. The stiffness distributions of the atherosclerotic aorta from a rabbit were obtained, for which the values of peak displacement and the shear wave velocity were 3.7 ± 1.2 µm and 0.38 ± 0.19 m s −1 for the lipid-rich plaques, and 1.0 ± 0.2 µm and 3.45 ± 0.45 m s −1 for the arterial walls, respectively. These results indicate that IVUS elasticity imaging can be used to distinguish the elastic properties of plaques and vessels.

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