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 ◽  
...  

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.

2020 ◽  
Vol 15 (2) ◽  
pp. 42-48
Author(s):  
E. V. Kovaleva ◽  
T. Yu. Danzanova ◽  
G. T. Sinyukova ◽  
E. A. Gudilina ◽  
P. I. Lepedatu ◽  
...  

The objective: to evaluate the possibilities of ARFI technology (Acoustic Radiation Force Impulse), including Virtual Touch™ Tissue Imaging (VTI) and Virtual Touch™ Tissue Quantification (VTQ) for differentiation of lymphomatous and metastatic superficial lymphadenopathy.Materials and methods. The prospective study included 138 patients with enlarged superficial lymph nodes (LN). Based on a previous histological examination, patients were divided into two groups: 1st group (n = 108) – patients with non-Hodgkin’s lymphomas and Hodgkin’s lymphoma; 2nd group (n = 30) – patients with metastasis of solid tumors in superficial LN. All patients underwent ultrasound elastography of the enlarged LN using ARFI technology. In VTI study the Area Ratio parameter was evaluated, and the minimum and average values of the shear wave velocity were estimated in VTQ study.Results. According to the results of VTI study the Area Ratio parameter for enlarged LN in lymphoma (1st group) and for metastatic lymphadenopathy (2 nd group) were 1.031 ± 0.197 and 0.851 ± 0.15, respectively (p = 0.000009). The cut off value of the Area Ratio parameter was 0.901 with sensitivity, specificity and accuracy 80.6, 70.0 and 78.8 %, respectively. Minimum values of shear wave velocities for 1st and 2 nd groups were 1.980 ± 0.557 and 2.214 ± 0.367 m/s, respectively (p = 0.032). The cut off values of the average shear wave velocity in the differentiating of lymphomatous and metastatic lymphadenopathy are determined at the level of 2.00 m/s, with sensitivity of 70.0 %, specificity of 59.3 %, and accuracy of 61.6 %.Conclusion. Ultrasound elastography with ARFI technology demonstrated statistically significant differences in the Area Ratio parameter and in the minimum shear wave velocity in the enlarged superficial LN in lymphoma and with metastasis that can be used as a preliminary non-invasive differential diagnosis of enlarged superficial LN in these conditions. Moreover, the Area Ratio parameter has a statistically more significant effect on differentiating of lymphomatous and metastatic lymphadenopathy.


2019 ◽  
Vol 35 (3) ◽  
pp. 182-187
Author(s):  
Amitabh Dashottar ◽  
Erin Montambault ◽  
Jeffrey R. Betz ◽  
Kevin D. Evans

Although ultrasound elastography is established as a reliable and valid tool for assessment of skeletal muscles, guidelines around the technical specifications, data selection, and acquisition parameters still lack consensus. One such parameter is the use of the quantification box (Q-box) that calculates the shear wave velocity/modulus, within a selected region of interest (ROI). Currently, no data compare the effect of the elastographic area within the ROI to the mean shear wave velocity calculations, using a Q-box. In this study, the mean shear wave velocity calculated over a smaller (single Q-box) ROI is compared to the mean shear wave velocity calculated over maximum area of elastogram, within a ROI. Comparison of mean shear wave velocity revealed a significant difference ( t = 2.79, P = .007) between the means calculated over maximum area of elastogram for only nonuniform elastograms. The rater agreement for the classification scheme was assessed (κ = 0.85). To prevent possible overestimation of shear wave velocities, it may be necessary to place the Q-box over the maximum elastographic area.


Geophysics ◽  
2014 ◽  
Vol 79 (4) ◽  
pp. D205-D216 ◽  
Author(s):  
Xinding Fang ◽  
Michael C. Fehler ◽  
Arthur Cheng

Formation elastic properties near a borehole may be altered from their original state due to the stress concentration around the borehole. This can lead to an incorrect estimation of formation elastic properties measured from sonic logs. Previous work has focused on estimating the elastic properties of the formation surrounding a borehole under anisotropic stress loading. We studied the effect of borehole stress concentration on sonic logging in a moderately consolidated Berea sandstone using a two-step approach. First, we used an iterative approach, which combines a rock-physics model and a finite-element method, to calculate the stress-dependent elastic properties of the rock around a borehole subjected to an anisotropic stress loading. Second, we used the anisotropic elastic model obtained from the first step and a finite-difference method to simulate the acoustic response of the borehole. Although we neglected the effects of rock failure and stress-induced crack opening, our modeling results provided important insights into the characteristics of borehole P-wave propagation when anisotropic in situ stresses are present. Our simulation results were consistent with the published laboratory measurements, which indicate that azimuthal variation of the P-wave velocity around a borehole subjected to uniaxial loading is not a simple cosine function. However, on field scale, the azimuthal variation in P-wave velocity might not be apparent at conventional logging frequencies. We found that the low-velocity region along the wellbore acts as an acoustic focusing zone that substantially enhances the P-wave amplitude, whereas the high-velocity region caused by the stress concentration near the borehole results in a significantly reduced P-wave amplitude. This results in strong azimuthal variation of P-wave amplitude, which may be used to infer the in situ stress state.


2016 ◽  
Vol 45 (11) ◽  
pp. 1541-1551 ◽  
Author(s):  
Andrea B. Rosskopf ◽  
Elias Bachmann ◽  
Jess G. Snedeker ◽  
Christian W. A. Pfirrmann ◽  
Florian M. Buck

2020 ◽  
Vol 26 (13-14) ◽  
pp. 720-732
Author(s):  
Emma S. Gargus ◽  
Kristen L. Jakubowski ◽  
Gabriel A. Arenas ◽  
Scott J. Miller ◽  
Sabrina S. M. Lee ◽  
...  

Проведена ультразвуковая эластографическая оценка злокачественных опухолей яичка у 31 пациента в возрасте от 19 до 65 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%)). Пациенты были разделены на группы в зависимости от морфологических видов опухоли (семинома (n = 18) и несеминомные герминогенные опухоли (n = 12, в 2 случаях семинома была одним из компонентов смешанной герминогенной опухоли) (1 случай спермоцитарной семиномы был исключен из этой части анализа); тератома как компонент смешанной герминогенной опухоли (n = 6) и остальные герминогенные опухоли (n = 25)). Режим эластографии сдвиговой волной использовался после предварительной серошкальной визуализации яичек на аппаратах Aplio 500 (Toshiba, Япония) и Aixplorer (Supersonic Imagine, Франция) (линейные датчики 5-14 и 4-15 МГц соответственно). Технические аспекты: различия между измерениями значений модуля Юнга в опухолях яичка на аппарате (1) Aplio 500 и аппарате (2) Aixplorer недостоверны (P = 0,95). Корреляция между значениями модуля Юнга, полученными на двух приборах, высокая (rs = 0,86, P = 0,0137). Значения модуля Юнга в опухолях яичка достоверно выше по сравнению с эхографически неизмененной паренхимой ипсилатерального яичка (P = 0,0017 для указанных сравнений на двух аппаратах) и паренхимой эхографически неизмененного контрлатерального яичка (P = 0,0017 для указанных сравнений на двух аппаратах) на фоне отсутствия достоверности различий между значениями модуля Юнга в двух яичках (неизмененные участки ипсилатерального яичка и паренхима среднего сегмента контрлатерального яичка) (P = 0,4057 и P = 0,8480 для аппаратов 1 и 2 соответственно). Морфологические аспекты (аппарат Aixplorer): медиана Emean в группе семиномы (n = 18) составила 110,3 кПа, 25-75-й процентили - 77,6-159,0 кПа, 5-95-й процентили - 16.5- 222,1 кПа, минимальное - максимальное значения - 15,3-241,4 кПа; в группе несеминомных герминогенных опухолей (n = 12) - 109,9 кПа, 83,0-129,0 кПа, 55.5- 156,8 кПа, 54,2-157,8 кПа (различия недостоверны при P=0,9325). Отсутствие достоверности различий также было определено при сравнении смешанных герминогенных опухолей, в составе которых была тератома, и остальных опухолей (P = 0,5823). Различия значений индексов жесткости (индекс жесткости 1 - отношение значений Emean в областях опухоли и эхографически неизмененной паренхимы ипсилатерального яичка, индекс жесткости 2 - отношение значений Emean в областях опухоли и паренхимы эхографически неизмененного контрлатерального яичка, индекс жесткости 3 - внутриопухолевый индекс жесткости с учетом участков с максимальной и минимальной жесткостью внутри объемного образования) у пациентов с семиномами и несеминомными герминогенными опухолями не выявлены. Ключевые слова: мультипараметрическая ультразвуковая диагностика, ультразвуковая эластография, эластография сдвиговой волной, жесткость, модуль Юнга, скорость сдвиговой волны, рак яичка, семинома, несеминомные герминогенные опухоли, multiparametric ultrasound, ultrasound elastography, shear wave elastography, stiffness, Young’s modulus, shear wave velocity, testicular cancer, seminoma, nonseminomatous germ cell tumors


1998 ◽  
Vol 7 (3) ◽  
pp. 219-224 ◽  
Author(s):  
Chris L de Korte ◽  
E.Ignacio Cespedes ◽  
Anton F.W van der Steen ◽  
Gerard Pasterkamp ◽  
Nicolaas Bom

Sign in / Sign up

Export Citation Format

Share Document