scholarly journals High-Resolution Shear Wave Imaging of the Human Cornea Using a Dual-Element Transducer

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4244 ◽  
Author(s):  
Pei-Yu Chen ◽  
Cho-Chiang Shih ◽  
Wei-Chen Lin ◽  
Teng Ma ◽  
Qifa Zhou ◽  
...  
Keyword(s):  
High Resolution ◽  
Ultraviolet Radiation ◽  
Young’S Modulus ◽  
Shear Wave ◽  
Shear Wave Velocity ◽  
Young's Modulus ◽  
Quantitative Estimation ◽  
Human Cornea ◽  
Shear Wave Imaging ◽  
Wave Imaging

Estimating the corneal elasticity can provide valuable information for corneal pathologies and treatments. Ophthalmologic pathologies will invariably cause changes to the elasticity of the cornea. For example, keratoconus and the phototoxic effects of ultraviolet radiation usually increase the corneal elasticity. This makes a quantitative estimation of the elasticity of the human cornea important for ophthalmic diagnoses. The present study investigated the use of a proposed high-resolution shear wave imaging (HR-SWI) method based on a dual-element transducer (comprising an 8-MHz element for pushing and a 32-MHz element for imaging) for measuring the group shear wave velocity (GSWV) of the human cornea. An empirical Young’s modulus formula was used to accurately convert the GSWV to Young’s modulus. Four quantitative parameters, bias, resolution, contrast, and contrast-to-noise ratio (CNR), were measured in gelatin phantoms with two different concentrations (3% and 7%) to evaluate the performance of HR-SWI. The biases of gelatin phantoms (3% and 7%) were 5.88% and 0.78%, respectively. The contrast and CNR were 0.76, 1.31 and 3.22, 2.43 for the two-side and two-layer phantoms, respectively. The measured image resolutions of HR-SWI in the lateral and axial directions were 72 and 140 μm, respectively. The calculated phase SWV (PSWV) and their corresponding Young’s modulus from six human donors were 2.45 ± 0.48 m/s (1600 Hz) and 11.52 ± 7.81 kPa, respectively. All the experimental results validated the concept of HR-SWI and its ability for measuring the human corneal elasticity.

Evaluation of the Effect of Tissue Compression on the Results of Shear Wave Elastography Measurements

2018 ◽  
Vol 40 (6) ◽  
pp. 380-393 ◽  
Author(s):  
Jaromir Vachutka ◽  
Zuzana Sedlackova ◽  
Tomas Furst ◽  
Miroslav Herman ◽  
Jan Herman ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Shear Wave ◽  
Ex Vivo ◽  
Young's Modulus ◽  
Shear Wave Elastography ◽  
Shear Wave Imaging ◽  
Phantom Measurements ◽  
Wave Imaging ◽  
Tissue Compression

Shear wave imaging is considered to be more precise and less operator dependent when compared with strain imaging. It enables quantitative and reproducible data (Young’s modulus of the imaged tissue). However, results of shear wave imaging can be affected by a variety of different factors. The aim of this study is to evaluate the effect of the pressure applied by the ultrasound probe during examination on the measured values of Young’s modulus. The effect of the tissue compression on the results of the real-time shear wave elastography was evaluated via the gelatine phantom measurements, via the ex vivo experiments with pig liver, and via the in vivo measurements of the thyroid gland stiffness on healthy volunteers. The results of our measurements confirmed that the measured value of Young’s modulus increases with the increasing pressure applied on the imaged object. The highest increase was observed during the ex vivo experiments (400%), and the lowest increase was detected in the case of the phantom measurements (8%). A two- to threefold increase in Young’s modulus was observed between the minimum and maximum pressure in the case of the in vivo elastography measurements of thyroid gland. The Veronda-Westman theoretical model was used for the description of the tissue nonlinearity. We conclude that tissue compression by the force exerted on the probe can significantly affect the results of the real-time shear wave elastography measurements. Minimum pressure should be used when measuring the absolute value of Young’s modulus of superficial organs.

Far _ Near Wellbore Fracture Characterization Using High Resolution Borehole Images and Deep Shear Wave Imaging

2020 ◽  
Author(s):  
N. Kerrouche ◽  
A. Alhammadi ◽  
A. AlMershed ◽  
H. Al-Khateeb ◽  
D.N. Tiwary ◽  
...  
Keyword(s):  
High Resolution ◽  
Shear Wave ◽  
Fracture Characterization ◽  
Shear Wave Imaging ◽  
Wave Imaging

Shear wave velocity measurement of upper trapezius muscle by color Doppler shear wave imaging

2017 ◽  
Vol 45 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Atsushi Yamamoto ◽  
Yoshiki Yamakoshi ◽  
Takashi Ohsawa ◽  
Hitoshi Shitara ◽  
Tsuyoshi Ichinose ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Velocity Measurement ◽  
Color Doppler ◽  
Trapezius Muscle ◽  
Shear Wave Imaging ◽  
Upper Trapezius ◽  
Wave Imaging ◽  
Upper Trapezius Muscle

Ультразвуковая эластография сдвиговой волной в характеризации рака яичка

2017 ◽  
pp. 13-24
Keyword(s):  
Testicular Cancer ◽  
Young’S Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Young's Modulus ◽  
Shear Wave Elastography ◽  
Ultrasound Elastography ◽  
Multiparametric Ultrasound

Проведена мультипараметрическая ультразвуковая оценка злокачественных опухолей яичка у 31 пациента в возрасте от 19 до 65 лет (медиана - 33 года, 25-75-й процентили - 27-40 лет). Во всех случаях было одностороннее поражение. Во всех случаях диагноз подтвержден морфологически (семинома - 18 (58,1%), эмбриональная карцинома - 5 (16,1%), смешанные герминогенные опухоли - 7 (22,6%), спермоцитарная семинома - 1 (3,2%)). В 13 (41,9%) случаях была стадия pT1, в 15 (48,4%) - pT2, в 3 (9,7%) - pT3. Режим эластографии сдвиговой волной использовался после предварительной серошкальной визуализации яичек (аппарат Aixplorer (Supersonic Imagine, Франция), линейный датчик 4-15 МГц). Медиана Emean в максимально жестких участках опухоли (n = 31) составила 109,3 кПа, 25-75-й процентили - 77,7-145,5 кПа, 5-95-й процентили - 18,7-192,4 кПа, минимальное - максимальное значения - 15,3-241,4 кПа. Значения модуля Юнга (Emean) в области опухоли достоверно выше при сравнении с эхографически неизмененной паренхимой ипсилатерального яичка (1), эхографически неизмененным контрлатеральным яичком (2) и нормативными данными (3) (P 0,0001 для трех сравнений). Качественная оценка эластографической картины (деление на типы эластографической картины) дает представление о жесткостной природе опухоли, однако зависит от выбранной шкалы. На настоящий момент целесообразно ее использование именно для идентификации наиболее жестких участков образования с проведением последующих измерений. Не выявлены значимые корреляции значений модуля Юнга ни с объемом опухоли, ни с максимальным ее линейным размером, ни со стадиями pT, ни с морфологическими типами. Выявлена умеренная прямая корреляция значений индекса жесткости 1 (отношение значений Emean в областях опухоли и эхографически неизмененной паренхимы ипсилатерального яичка при ее наличии) со стадиями pT (τк = 0,32, P = 0,0305). Эластометрия в качестве одного из звеньев мультипараметрической ультразвуковой диагностики дает новую информацию о жесткости опухолей яичка, что может быть использовано в рутинном диагностическом процессе с учетом низкой временной затратности методики. Ключевые слова: мультипараметрическая ультразвуковая диагностика, ультразвуковая эластография, эластография сдвиговой волной, жесткость, модуль Юнга, скорость сдвиговой волны, рак яичка, multiparametric ultrasound, ultrasound elastography, shear wave elastography, stiffness, Young’s modulus, shear wave velocity, testicular cancer

FROM THE BOREHOLE WALL INTO THE FORMATION – COMBINING BOREHOLE IMAGES WITH DEEP SHEAR WAVE IMAGING TECHNOLOGY

2019 ◽  
Author(s):  
Stefan Schimschal ◽  
Stephen Fayers ◽  
Nicklas Ritzmann ◽  
Martin Cox ◽  
Iain Whyte
Keyword(s):  
Shear Wave ◽  
Borehole Wall ◽  
Imaging Technology ◽  
Shear Wave Imaging ◽  
Wave Imaging

scholarly journals Natural shear wave imaging using vocal tract vibrations: Introducing vocal passive elastography (V-PE) to thyroid elasticity mapping

2021 ◽  
Vol 118 (2) ◽  
pp. 023702
Author(s):  
Steve Beuve ◽  
Samuel Callé ◽  
Elise Khoury ◽  
Emmanuel Gilles Simon ◽  
Jean-Pierre Remenieras
Keyword(s):  
Shear Wave ◽  
Vocal Tract ◽  
Shear Wave Imaging ◽  
Wave Imaging

A Color-Doppler Shear-Wave-Imaging Phase-reconstruction Method Using Four Color Flow Images

2016 ◽  
Vol 39 (3) ◽  
pp. 172-188
Author(s):  
Naoki Sunaguchi ◽  
Yoshiki Yamakoshi ◽  
Takahito Nakajima
Keyword(s):  
Image Quality ◽  
Shear Wave ◽  
Initial Phase ◽  
Color Doppler ◽  
Reconstruction Method ◽  
Phase Reconstruction ◽  
Color Flow ◽  
Shear Wave Imaging ◽  
Wave Imaging ◽  
Phase Map

This study investigates shear wave phase map reconstruction using a limited number of color flow images (CFIs) acquired with a color Doppler ultrasound imaging instrument. We propose an efficient reconstruction method to considerably reduce the number of CFIs required for reconstruction and compare this method with Fourier analysis-based color Doppler shear wave imaging. The proposed method uses a two-step phase reconstruction process, including an initial phase map derived from four CFIs using an advanced iterative algorithm of optical interferometry. The second step reduces phase artifacts in the initial phase map using an iterative correction procedure that cycles between the Fourier and inverse Fourier domains while imposing directional filtering and total variation regularization. We demonstrate the efficacy of this method using synthetic and experimental data of a breast phantom and human breast tissue. Our results show that the proposed method maintains image quality and reduces the number of CFIs required to four; previous methods have required at least 32 CFIs to achieve equivalent image quality. The proposed method is applicable to real-time shear wave elastography using a continuous shear wave produced by a mechanical vibrator.

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