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Wu YC, Xu GX, Chen C, Chuang YH, Huang CC. Estimating the viscoelastic anisotropy of human skin through high-frequency ultrasound elastography. Med Phys 2024. [PMID: 39225581 DOI: 10.1002/mp.17372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 08/10/2024] [Accepted: 08/11/2024] [Indexed: 09/04/2024] Open
Abstract
BACKGROUND The skin is the largest organ of the human body and serves distinct functions in protecting the body. The viscoelastic properties of the skin play a key role in supporting the skin-healing process, also it may be changed due to some skin diseases. PROPOSE In this study, high-frequency ultrasound (HFUS) elastography based on a Lamb wave model was used to noninvasively assess the viscoelastic anisotropy of human skin. METHOD Elastic waves were generated through an external vibrator, and the wave propagation velocity was measured through 40 MHz ultrafast HFUS imaging. Through the use of a thin-layer gelatin phantom, HFUS elastography was verified to produce highly accurate estimates of elasticity and viscosity. In a human study involving five volunteers, viscoelastic anisotropy was assessed by rotating an ultrasound transducer 360°. RESULTS An oval-shaped pattern in the elasticity of human forearm skin was identified, indicating the high elastic anisotropy of skin; the average elastic moduli were 24.90 ± 6.63 and 13.64 ± 2.67 kPa along and across the collagen fiber orientation, respectively. The average viscosity of all the recruited volunteers was 3.23 ± 0.93 Pa·s. CONCLUSIONS Although the examined skin exhibited elastic anisotropy, no evident viscosity anisotropy was observed.
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Affiliation(s)
- Yu-Chen Wu
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Guo-Xuan Xu
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Chien Chen
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Hsiang Chuang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Chih-Chung Huang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
- Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan
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Chen X, Li X, Turco S, van Sloun RJG, Mischi M. Ultrasound Viscoelastography by Acoustic Radiation Force: A State-of-the-Art Review. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2024; 71:536-557. [PMID: 38526897 DOI: 10.1109/tuffc.2024.3381529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
Ultrasound elastography (USE) is a promising tool for tissue characterization as several diseases result in alterations of tissue structure and composition, which manifest as changes in tissue mechanical properties. By imaging the tissue response to an applied mechanical excitation, USE mimics the manual palpation performed by clinicians to sense the tissue elasticity for diagnostic purposes. Next to elasticity, viscosity has recently been investigated as an additional, relevant, diagnostic biomarker. Moreover, since biological tissues are inherently viscoelastic, accounting for viscosity in the tissue characterization process enhances the accuracy of the elasticity estimation. Recently, methods exploiting different acquisition and processing techniques have been proposed to perform ultrasound viscoelastography. After introducing the physics describing viscoelasticity, a comprehensive overview of the currently available USE acquisition techniques is provided, followed by a structured review of the existing viscoelasticity estimators classified according to the employed processing technique. These estimators are further reviewed from a clinical usage perspective, and current outstanding challenges are discussed.
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Liu Y, Saharkhiz N, Hossain MM, Konofagou EE. Optimization of the Tracking Beam Sequence in Harmonic Motion Imaging. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2024; 71:102-116. [PMID: 37917522 PMCID: PMC10871064 DOI: 10.1109/tuffc.2023.3329729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2023]
Abstract
Harmonic motion imaging (HMI) is an ultrasound elastography technique that estimates the viscoelastic properties of tissues by inducing localized oscillatory motion using focused ultrasound (FUS). The resulting displacement, assumed to be inversely proportional to the tissue local stiffness, is estimated using an imaging array based on RF speckle tracking. In conventional HMI, this is accomplished with plane-wave (PW) imaging, which inherently suffers from low lateral resolution. Coherent PW compounding (PWC) leverages spatial and temporal resolution using synthetic focusing in transmit. In this study, we introduced focused imaging with parallel tracking in HMI and compared parallel tracking of various transmit F-numbers (F/2.6, 3, 4, and 5) qualitatively and quantitatively with PW and PWC imaging at various compounded angle ranges (6°, 12°, and 18°). An in silico model of a 56-kPa spherical inclusion (diameter: 3.6 mm) embedded in a 5.3-kPa background and a 5.3-kPa elastic phantom with cylindrical inclusions (Young's moduli: 22-56 kPa, diameters: 2.0-8.6 mm) were imaged to assess different tracking beam sequences. Speckle biasing in displacement estimation associated with parallel tracking was also investigated and concluded to be negligible in HMI. Parallel tracking in receive (Rx) resulted in 2%-7% and 8%-12% increase compared to PW imaging ( ) in HMI contrast and contrast-to-noise ratio in silico and phantoms. Focused imaging with parallel tracking in Rx was concluded to be most robust among PW and PWC imaging for displacement estimation, and its preclinical feasibility was demonstrated in postsurgical human cancerous breast tissue specimens and in vivo murine models of breast cancer.
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Arslan H, Küçükbaş GN, Türkoğlu S, Akdemir Z, Yokuş A, Gündüz AM, Karaman E, Şahin HG. Use of Virtual Touch Tissue Quantification Elastography Technique in Fetal Lung Maturation: A Preliminary Study. Ultrasound Q 2023; 39:134-137. [PMID: 37093671 DOI: 10.1097/ruq.0000000000000642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
ABSTRACT This study is an analysis of fetal lung stiffness by virtual touch tissue quantification (VTTQ) elastography to predict fetal lung maturation. Evaluation of fetal lungs was first performed in B mode, and fetal lungs were analyzed at 3 different periods at third trimester in each pregnant woman, at 28 to 31, 32 to 36, and 37 to 41 weeks. Fetal lung elastography was performed at regions with the least acoustic shadow and far from ribs and heart. Each fetal lung assessment were done by taking mean lung stiffness obtained by measuring stiffness of both left and right fetal lungs. T test analysis showed no significant difference in fetal lung stiffness between male and female fetuses among 3 gestational periods. Analysis of variance was performed to evaluate fetal lung stiffness of the fetuses at 3 different gestational periods (28-31, 32-36, and 37-41 weeks). This analysis showed significant difference ( P < 0.01). Duncan multiple comparison analysis did not show significant difference in fetal lung stiffness between 28 and 31 weeks and 32 and 36 weeks, whereas fetal lung stiffness of fetuses at 37 to 41 weeks were significantly greater ( P < 0.01). This study is first step to analyze fetal lung maturation noninvasively using VTTQ elastography technique by measuring fetal lung stiffness.
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Affiliation(s)
| | - Gökçe Naz Küçükbaş
- Obstetrics and Gynecology, Van Yuzuncu Yil University, Faculty of Medicine
| | - Saim Türkoğlu
- Department of Radiology, Van Training and Research Hospital, Van, Turkey
| | | | | | | | - Erbil Karaman
- Obstetrics and Gynecology, Van Yuzuncu Yil University, Faculty of Medicine
| | - Hanım Güler Şahin
- Obstetrics and Gynecology, Van Yuzuncu Yil University, Faculty of Medicine
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Saharkhiz N, Kamimura HAS, Konofagou EE. The impact of amplitude modulation frequency in harmonic motion imaging on inclusion characterization. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:1768-1779. [PMID: 37202245 PMCID: PMC10392769 DOI: 10.1016/j.ultrasmedbio.2023.03.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 03/28/2023] [Accepted: 03/30/2023] [Indexed: 05/20/2023]
Abstract
OBJECTIVE Ultrasound elasticity imaging techniques aim to provide a non-invasive characterization of tissue mechanical properties to detect pathological changes and monitor disease progression. Harmonic motion imaging (HMI) is an ultrasound-based elasticity imaging technique that utilizes an oscillatory acoustic radiation force to induce localized displacements and estimate relative tissue stiffness. Previous studies have applied a low amplitude modulation (AM) frequency of 25 or 50 Hz in HMI to assess the mechanical properties of different tissue types. In this study, we investigate the dependence of AM frequency in HMI and whether the frequency can be adjusted based on the size and mechanical properties of the underlying medium for enhanced image contrast and inclusion detection. METHODS A tissue-mimicking phantom with embedded inclusions at different sizes and stiffnesses was imaged within a range of AM frequencies from 25 to 250 Hz at 25-Hz step size. DISCUSSION The AM frequency at which the maximum contrast and CNR are achieved depends on the size and stiffness of the inclusions. A general trend shows that contrast and CNR peak at higher frequencies for smaller inclusions. In addition, for some inclusions with the same size but different stiffnesses, the optimized AM frequency increases with the stiffness of the inclusion. Nevertheless, there is a shift between the frequencies at which the contrast peaks and those with maximum CNR. Finally, in agreement with the phantom findings, imaging an ex-vivo human specimen with a 2.7-cm breast tumor at a range of AM frequencies showed that the highest contrast and CNR are achieved at the AM frequency of 50 Hz. CONCLUSION These findings indicate that the AM frequency can be optimized in different applications of HMI, especially in the clinic, for improved detection and characterization of tumors with different geometries and mechanical properties.
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Affiliation(s)
- Niloufar Saharkhiz
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| | - Hermes A S Kamimura
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| | - Elisa E Konofagou
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA; Department of Radiology, Columbia University, New York, NY 10027, USA.
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Sakcak B, Alkan M, Denizli R, Farisoğullari N, Kara Ö, Ayhan ŞG, Tanacan A, Şahin D. Point shear wave velocity(pSWV) evaluation of the placenta of pregnant women who had recovered from COVID-19: A prospective cohort study from a tertiary pandemic center. Placenta 2022; 128:57-61. [PMID: 36067701 PMCID: PMC9395301 DOI: 10.1016/j.placenta.2022.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 07/03/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022]
Abstract
INTRODUCTION To assess the placental elasticity using point shear wave velocity (pSWV) in pregnant women who had recovered from coronavirus COVID-19. METHODS A total of 40 pregnant women who had recovered from moderate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and 40 healthy pregnant women were included in this study. We evaluated placental elasticity by using transabdominal pSWV method. Three measurements were made, and their average was accepted as the mean placental velocity value in each case. The results were compared between the post-COVID-19 and control groups. RESULTS The mean pSWV values were significantly higher in the post-COVID-19 group compared to the control group, indicating that the women with a history of COVID-19 had stiffer placentas. Furthermore, the pSWV values were significantly and positively correlated with the uterine artery pulsatility index. We also found that the NICU requirement was statistically higher in the post-COVID 19 group. DISCUSSION The pregnant women who had recovered from COVID-19 had rigid placentas than the healthy controls. The use of pSWV for the assessment of placental velocity may provide valuable information in the diagnosis and management of post-COVID-19 patients as a complementary tool to the existing ultrasonography methods.
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Affiliation(s)
- Bedri Sakcak
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey.
| | - Mihriban Alkan
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey
| | - Ramazan Denizli
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey
| | - Nihat Farisoğullari
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey
| | - Özgür Kara
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey
| | - Şule Göncü Ayhan
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey
| | - Atakan Tanacan
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey
| | - Dilek Şahin
- Department of Obstetrics and Gynecology, Ministry of Health, Ankara City Hospital, Ankara, Turkey; University of Health Sciences, Ankara City Hospital, Ankara, Turkey
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Zhang L, Lin Z, Zeng L, Zhang F, Sun L, Sun S, Wang P, Xu M, Zhang J, Liang X, Ge H. Ultrasound-induced biophysical effects in controlled drug delivery. SCIENCE CHINA. LIFE SCIENCES 2022; 65:896-908. [PMID: 34453275 DOI: 10.1007/s11427-021-1971-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/27/2021] [Indexed: 12/30/2022]
Abstract
Ultrasound is widely used in biomedical engineering and has applications in conventional diagnosis and drug delivery. Recent advances in ultrasound-induced drug delivery have been summarized previously in several reviews that have primarily focused on the fabrication of drug delivery carriers. This review discusses the mechanisms underlying ultrasound-induced drug delivery and factors affecting delivery efficiency, including the characteristics of drug delivery carriers and ultrasound parameters. Firstly, biophysical effects induced by ultrasound, namely thermal effects, cavitation effects, and acoustic radiation forces, are illustrated. Secondly, the use of these biophysical effects to enhance drug delivery by affecting drug carriers and corresponding tissues is clarified in detail. Thirdly, recent advances in ultrasound-triggered drug delivery are detailed. Safety issues and optimization strategies to improve therapeutic outcomes and reduce side effects are summarized. Finally, current progress and future directions are discussed.
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Affiliation(s)
- Lulu Zhang
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Zhuohua Lin
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Lan Zeng
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Fan Zhang
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Lihong Sun
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Suhui Sun
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Ping Wang
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Menghong Xu
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Jinxia Zhang
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China
| | - Xiaolong Liang
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China.
| | - Huiyu Ge
- Department of Ultrasound, Peking University Third Hospital, Beijing, 100191, China.
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Telichko AV, Dahl JJ, Herickhoff CD. Cylindrical Transducer Array for Intravascular Shear Wave Elasticity Imaging: Preliminary Development. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:1077-1087. [PMID: 34990357 DOI: 10.1109/tuffc.2022.3140976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We present an intravascular ultrasound (IVUS) transducer array designed to enable shear wave elasticity imaging (SWEI) of arteries for the detection and characterization of atherosclerotic soft plaques. Using a custom dicing fixture, we have fabricated single-element and axially-segmented array transducer prototypes from 4.6-Fr to 7.6-Fr piezoceramic tubes, respectively. Focused excitation of the array prototype at 4 MHz yielded a focal gain of 5× in intensity, for an estimated 60 mW/cm2 [Formula: see text] and 1.6-MPa negative peak pressure at 4.5-mm range in water. The single-element transducer generated a peak radial displacement of [Formula: see text] in a uniform elasticity phantom, with axial shear waves detectable by an external linear array probe up to 5 mm away from the excitation plane. In a vessel phantom with a soft inclusion, the array prototype generated peak displacements of 2.2 and [Formula: see text] in the soft inclusion and vessel wall regions, respectively. A SWEI image of the vessel phantom was reconstructed, with measured shear wave speed (SWS) of 1.66 ± 0.91 m/s and 0.97 ± 0.59 m/s for the soft inclusion and vessel wall regions, respectively. The array prototype was also used to obtain a SWEI image of an ex vivo porcine artery, with a mean SWS of 3.97 ± 1.12 m/s. These results suggest that a cylindrical intravascular ultrasound (IVUS) transducer array could be made capable of SWEI for atherosclerotic plaque detection in coronary arteries.
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Lin H, Chen Y, Xie S, Yu M, Deng D, Sun T, Hu Y, Chen M, Chen S, Chen X. A Dual-modal Imaging Method Combining Ultrasound and Electromagnetism for Simultaneous Measurement of Tissue Elasticity and Electrical Conductivity. IEEE Trans Biomed Eng 2022; 69:2499-2511. [PMID: 35119996 DOI: 10.1109/tbme.2022.3148120] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The mechanical and electrical properties of soft tissues are relative to soft tissues' pathological state. Modern medical imaging devices have shown a trend to multi-modal imaging, which will provide complementary functional information to improve the accuracy of disease diagnosis. However, no method or system can simultaneously measure the mechanical and electrical properties of the soft tissue. In this study, we proposed a novel dual-modal imaging method integrated by shear wave elasticity imaging (SWEI) and Magneto-acousto-electrical tomography (MAET) to measure soft tissue's elasticity and conductivity simultaneously. A dual-modal imaging system based on a linear array transducer is built, and the imaging performances of MAET and SWEI were respectively evaluated by phantoms experiment and \textit{in vitro} experiment. Conductivity phantom experiments show that the MAET in this dual-modal system can image conductivity gradient as low as 0.4 S/m. The phantom experiments show that the reconstructed 2-D elasticity maps of the phantoms with inclusions with a diameter larger than 5 mm are relatively accurate. \textit{In vitro} experiments show that the elasticity parameter can significantly distinguish the changes in tissue before and after heating. This study first proposes a method that can simultaneously obtain tissue elasticity and electrical conductivity to the best of our knowledge. Although this paper just carried out the proof of concept experiments of the new method, it demonstrates great potential for disease diagnosis in the future.
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Villalobos Lizardi JC, Baranger J, Nguyen MB, Asnacios A, Malik A, Lumens J, Mertens L, Friedberg MK, Simmons CA, Pernot M, Villemain O. A guide for assessment of myocardial stiffness in health and disease. NATURE CARDIOVASCULAR RESEARCH 2022; 1:8-22. [PMID: 39196108 DOI: 10.1038/s44161-021-00007-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 11/10/2021] [Indexed: 08/29/2024]
Abstract
Myocardial stiffness is an intrinsic property of the myocardium that influences both diastolic and systolic cardiac function. Myocardial stiffness represents the resistance of this tissue to being deformed and depends on intracellular components of the cardiomyocyte, particularly the cytoskeleton, and on extracellular components, such as collagen fibers. Myocardial disease is associated with changes in myocardial stiffness, and its assessment is a key diagnostic marker of acute or chronic pathological myocardial disease with the potential to guide therapeutic decision-making. In this Review, we appraise the different techniques that can be used to estimate myocardial stiffness, evaluate their advantages and disadvantages, and discuss potential clinical applications.
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Affiliation(s)
- José Carlos Villalobos Lizardi
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Jerome Baranger
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Minh B Nguyen
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Atef Asnacios
- Laboratoire Matière et Systèmes Complexes, CNRS UMR 7057, Université de Paris, Paris, France
| | - Aimen Malik
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Joost Lumens
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | - Luc Mertens
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Mark K Friedberg
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Craig A Simmons
- Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Mathieu Pernot
- Physics for Medicine Paris, INSERM U1273, ESPCI Paris, CNRS UMR 8063, PSL Research University, Paris, France
| | - Olivier Villemain
- Division of Cardiology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
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Weng CC, Chen PY, Chou D, Shih CC, Huang CC. High Frequency Ultrasound Elastography for Estimating the Viscoelastic Properties of the Cornea Using Lamb Wave Model. IEEE Trans Biomed Eng 2020; 68:2637-2644. [PMID: 33306463 DOI: 10.1109/tbme.2020.3044066] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Estimating the elasticity distribution in the cornea is important because corneal elasticity is usually influenced by corneal pathologies and surgical treatments, especially for early corneal sclerosis. Because the thickness of the cornea is typically less than 1 mm, high-resolution ultrasound elastography as well as the Lamb wave model is required for viscoelastic property estimation. In the present study, an array high-frequency ultrasound (HFUS) elastography method based on ultrafast ultrasound imaging was proposed for estimating the viscoelastic properties of porcine cornea. METHODS The elastic wave was generated by an external vibrator, after which the wave propagation image was obtained using a 40-MHz array transducer. Viscoelasticity estimation was performed by fitting the phase velocity curve using the Lamb wave model. The performance of the proposed HFUS elastography system was verified using 2-mm-thick thin-layer gelatin phantoms with gelatin concentrations of 7% and 12%. Ex vivo experiments were carried out using fresh porcine cornea with artificial sclerosing. RESULTS Experimental results showed that the estimated elasticity was close to the standard value obtained in the phantom study when the Lamb wave model was used for elasticity measurement. However, the error between the standard elasticity values and the elasticity values estimated using group shear wave velocity was large. In the ex vivo eyeball experiments, the estimated elasticities and viscosities were respectively 9.1 ± 1.3 kPa and 0.5 ± 0.10 Pa·s for a healthy cornea and respectively 15.9 ± 2.1 kPa and 1.1 ± 0.12 Pa·s for a cornea with artificial sclerosis. A 3D HFUS elastography was also obtained for distinguishing the region of sclerosis in the cornea. CONCLUSION The experimental results demonstrated that the proposed HFUS elastography method has high potential for the clinical diagnosis of corneal diseases compared with other HFUS single-element transducer elastography systems.
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Schrier VJMM, Lin J, Gregory A, Thoreson AR, Alizad A, Amadio PC, Fatemi M. Shear wave elastography of the median nerve: A mechanical study. Muscle Nerve 2020; 61:826-833. [PMID: 32170959 DOI: 10.1002/mus.26863] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 02/03/2020] [Accepted: 03/10/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND Shear wave elastography (SWE) shows promise in peripheral neuropathy evaluation but has potential limitations due to tissue size and heterogeneity. We tested SWE sensitivity to elasticity change and the effect of probe position in a median nerve cadaver model. METHODS Ten specimens were used to measure median nerve elasticity under increasing loads using SWE and indentation. Measurements were compared using repeated-measures analysis of variance. RESULTS Indentation and SWE-based longitudinal nerve elasticity increased with tensile loading (P < .01), showing a similar relationship. Acquisition in a transverse plane showed lower values compared with longitudinal measurements, mostly under higher loads (P = .03), as did postdissection elasticity (P = .02). Elasticity did not change when measured proximal to the carpal tunnel. CONCLUSIONS Longitudinal SWE is sensitive to changes in median nerve elasticity. Measuring elasticity of peripheral nerves noninvasively could elucidate intra-neural pathology related to compression neuropathies, and proof to be of added value as a diagnostic or prognostic tool.
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Affiliation(s)
- Verena J M M Schrier
- Biomechanics Laboratory and Tendon and Soft Tissue Biology Laboratory, Mayo Clinic Minnesota, Rochester, Minnesota
| | - Jason Lin
- Biomechanics Laboratory and Tendon and Soft Tissue Biology Laboratory, Mayo Clinic Minnesota, Rochester, Minnesota
| | - Adriana Gregory
- Department of Radiology, Mayo Clinic Minnesota, Rochester, Minnesota
| | - Andrew R Thoreson
- Biomechanics Laboratory and Tendon and Soft Tissue Biology Laboratory, Mayo Clinic Minnesota, Rochester, Minnesota
| | - Azra Alizad
- Department of Radiology, Mayo Clinic Minnesota, Rochester, Minnesota
| | - Peter C Amadio
- Biomechanics Laboratory and Tendon and Soft Tissue Biology Laboratory, Mayo Clinic Minnesota, Rochester, Minnesota
| | - Mostafa Fatemi
- Department of Physiology and Biomedical Engineering, Mayo Clinic Minnesota, Rochester, Minnesota
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Hwang JA, Jeong WK, Song KD, Kang KA, Lim HK. 2-D Shear Wave Elastography for Focal Lesions in Liver Phantoms: Effects of Background Stiffness, Depth and Size of Focal Lesions on Stiffness Measurement. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:3261-3268. [PMID: 31493955 DOI: 10.1016/j.ultrasmedbio.2019.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 08/02/2019] [Accepted: 08/05/2019] [Indexed: 06/10/2023]
Abstract
The aim of this study was to determine the factors influencing stiffness and conspicuity of focal lesions in deep organs by focusing on target properties using 2-D shear wave elastography (SWE). Two normal (4 ± 1 kPa) and cirrhotic (16 ± 2 kPa) liver-mimicking phantoms with spherical inclusions (23 ± 3 kPa) were used. Inclusions of three sizes (20, 15 and 10 mm in diameter) were arranged in a row at depths of 3, 5 and 7 cm. Two observers acquired quantitative stiffness values and a qualitative five-grade morphologic score at each inclusion using SWE. The coefficients of variation (CVs) of stiffness were calculated to assess measurement reliability. The generalized estimating equation was used to identify whether stiffness, CV and morphologic score were independent of background stiffness, depth and size of inclusions and observer. In the quantitative assessment, stiffness of the inclusion and CV were dependent on the type of phantom and depth of inclusion (p < 0.001). There were no significant differences in stiffness and CV according to the observer. Morphologic score differed significantly only in the size of the inclusion (p < 0.001). When the depth of the inclusion was 7 cm, the stiffness was the highest, and the 10 mm-sized inclusions had lower morphologic scores than the other inclusions (all p values < 0.001). In conclusion, 2-D SWE assessment of focal lesions could be affected by background stiffness and depth of focal lesions, and may be limited in evaluating focal hepatic lesions.
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Affiliation(s)
- Jeong Ah Hwang
- Department of Radiology, Soonchunhyang University College of Medicine, Cheonan Hospital, Cheonan, Chungcheongnam-do, Korea
| | - Woo Kyoung Jeong
- Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
| | - Kyoung Doo Song
- Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Kyung A Kang
- Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyo K Lim
- Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Kakkad V, LeFevre M, Hollender P, Kisslo J, Trahey GE. Non-invasive Measurement of Dynamic Myocardial Stiffness Using Acoustic Radiation Force Impulse Imaging. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:1112-1130. [PMID: 30890282 PMCID: PMC6462419 DOI: 10.1016/j.ultrasmedbio.2018.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 12/20/2018] [Accepted: 12/21/2018] [Indexed: 05/23/2023]
Abstract
Myocardial stiffness exhibits cyclic variations over the course of the cardiac cycle. These trends are closely tied to the electromechanical and hemodynamic changes in the heart. Characterization of dynamic myocardialstiffness can provide insights into the functional state of the myocardium, as well as allow for differentiation between the underlying physiologic mechanisms that lead to congestive heart failure. Previous work has revealed the potential of acoustic radiation force impulse (ARFI) imaging to capture temporal trends in myocardial stiffness in experimental preparations such as the Langendorff heart, as well as on animals in open-chest and intracardiac settings. This study was aimed at investigating the potential of ARFI to measure dynamic myocardial stiffness in human subjects, in a non-invasive manner through transthoracic imaging windows. ARFI imaging was performed on 12 healthy volunteers to track stiffness changes within the interventricular septum in parasternal long-axis and short-axis views. Myocardial stiffness dynamics over the cardiac cycle was quantified using five indices: stiffness ratio, rates of relaxation and contraction and time constants of relaxation and contraction. The yield of ARFI acquisitions was evaluated based on metrics of signal strength and tracking fidelity such as displacement signal-to-noise ratio, signal-to-clutter level, temporal coherence of speckle and spatial similarity within the region of excitation. These were quantified using the mean ARF-induced displacements over the cardiac cycle, the contrast between the myocardium and the cardiac chambers, the minimum correlation coefficients of radiofrequency signals and the correlation between displacement traces across simultaneously acquired azimuthal beams, respectively. Forty-one percent of ARFI acquisitions were determined to be "successful" using a mean ARF-induced displacement threshold of 1.5 μm. "Successful" acquisitions were found to have higher (i) signal-to-clutter levels, (ii) temporal coherence and (iii) spatial similarity compared with "unsuccessful" acquisitions. Median values of these three metrics, between the two groups, were measured to be 13.42dB versus 5.42dB, 0.988 versus 0.976 and 0.984 versus 0.849, respectively. Signal-to-clutter level, temporal coherence and spatial similarity were also found to correlate with each other. Across the cohort of healthy volunteers, the stiffness ratio measured was 2.74 ± 0.86; the rate of relaxation, 7.82 ± 4.69/s; and the rate of contraction, -7.31±3.79 /s. The time constant of relaxation was 35.90 ± 20.04ms, and that of contraction was 37.24 ± 19.85ms. ARFI-derived indices of myocardial stiffness were found to be similar in both views. These results indicate the feasibility of using ARFI to measure dynamic myocardial stiffness trends in a non-invasive manner and also highlightthe technical challenges of implementing this method in the transthoracic imaging environment.
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Affiliation(s)
- Vaibhav Kakkad
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
| | - Melissa LeFevre
- Department of Cardiology, Duke University Hospital, Durham, North Carolina, USA
| | - Peter Hollender
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Joseph Kisslo
- Department of Cardiology, Duke University Hospital, Durham, North Carolina, USA
| | - Gregg E Trahey
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA; Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
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16
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High-Resolution Shear Wave Imaging of the Human Cornea Using a Dual-Element Transducer. SENSORS 2018; 18:s18124244. [PMID: 30513950 PMCID: PMC6308409 DOI: 10.3390/s18124244] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 11/22/2018] [Accepted: 11/30/2018] [Indexed: 12/23/2022]
Abstract
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.
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17
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Acoustic Radiation Force Based Ultrasound Elasticity Imaging for Biomedical Applications. SENSORS 2018; 18:s18072252. [PMID: 30002352 PMCID: PMC6069000 DOI: 10.3390/s18072252] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 07/03/2018] [Accepted: 07/11/2018] [Indexed: 01/02/2023]
Abstract
Pathological changes in biological tissue are related to the changes in mechanical properties of biological tissue. Conventional medical screening tools such as ultrasound, magnetic resonance imaging or computed tomography have failed to produce the elastic properties of biological tissues directly. Ultrasound elasticity imaging (UEI) has been proposed as a promising imaging tool to map the elastic parameters of soft tissues for the clinical diagnosis of various diseases include prostate, liver, breast, and thyroid gland. Existing UEI-based approaches can be classified into three groups: internal physiologic excitation, external excitation, and acoustic radiation force (ARF) excitation methods. Among these methods, ARF has become one of the most popular techniques for the clinical diagnosis and treatment of disease. This paper provides comprehensive information on the recently developed ARF-based UEI techniques and instruments for biomedical applications. The mechanical properties of soft tissue, ARF and displacement estimation methods, working principle and implementation instruments for each ARF-based UEI method are discussed.
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18
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Rominger MB, Kälin P, Mastalerz M, Martini K, Klingmüller V, Sanabria S, Frauenfelder T. Influencing Factors of 2D Shear Wave Elastography of the Muscle - An Ex Vivo Animal Study. Ultrasound Int Open 2018; 4:E54-E60. [PMID: 30250941 PMCID: PMC6148312 DOI: 10.1055/a-0619-6058] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/27/2018] [Accepted: 03/29/2018] [Indexed: 02/07/2023] Open
Abstract
OBJECTIVE To evaluate measurement confounders on 2D shear wave elastography (2D-SWE) elastography of muscle. MATERIALS AND METHODS Ex vivo , porcine muscle was examined with a GE LOGIQ E9 ultrasound machine with a 9 L linear (9 MHz) and C1-6 convex probe (operating at 2.5 or 6 MHz). The influence of different confounders on mean shear wave velocity (SWVmean) was analyzed: probes, pressure applied by probe, muscle orientation, together with the impact of different machine settings such as frequency, placement depth and size of region of interest (ROI). The mean of twelve repeated SWVmean measurements (m/s) and coefficient of variation (CV; standard deviation/mean in %) were assessed for each test configuration. RESULTS Reproducibility (CV) and maximum possible tissue depth of the linear probe were inferior to the convex probe. With the linear probe, there was a linear decrease of SWVmean with placement depth from 4.56 m/s to 1.81 m/s. A significant increase of SWVmean (p<0.001) was observed for larger ROI widths (range 3.96 m/s to 6.8 m/s). A change in the machine operation mode ('penetration' instead of 'general') led to a significant increase of SWVmean (p=0.04). SWVmean in the longitudinal direction of muscle was significantly higher than in cross section (p<0.001) (e. g. 4.56 m/s versus 3.42 m/s). An increase of linear probe pressure significantly increased muscle SWVmean from 5.29 m/s to 7.21 m/s (p<0.001). CONCLUSIONS 2D-SWE of muscle is influenced by a wealth of parameters. Therefore, standardization of measurement is advisable before application in clinical research studies and routine patient assessment.
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Affiliation(s)
- Marga B Rominger
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Pascal Kälin
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Monika Mastalerz
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Katharina Martini
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Volker Klingmüller
- Eidgenossische Technische Hochschule Zurich, Computer Vision Laboratory, Zurich, Switzerland
| | - Sergio Sanabria
- Eidgenossische Technische Hochschule Zurich, Computer Vision Laboratory, Zurich, Switzerland
| | - Thomas Frauenfelder
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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Arslan H, Tolunay HE, Cim N, Boza B, Yavuz A, İlik İ, Sahin HG, Yildizhan R. Shear-wave elastography – virtual touch tissue quantification of fetal placentas with a single umbilical artery. J Matern Fetal Neonatal Med 2018; 32:2481-2485. [DOI: 10.1080/14767058.2018.1439007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Harun Arslan
- Department of Radiology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - Harun Egemen Tolunay
- Department of Obstetrics and Gynecology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - Numan Cim
- Department of Obstetrics and Gynecology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - Barış Boza
- Department of Obstetrics and Gynecology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - Alpaslan Yavuz
- Department of Radiology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - İbrahim İlik
- Department of Radiology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - Hanim Guler Sahin
- Department of Obstetrics and Gynecology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
| | - Recep Yildizhan
- Department of Obstetrics and Gynecology, Faculty of Medicine, Yuzuncu Yil University, Van, Turkey
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20
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Multi-functional Ultrasonic Micro-elastography Imaging System. Sci Rep 2017; 7:1230. [PMID: 28450709 PMCID: PMC5430777 DOI: 10.1038/s41598-017-01210-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 03/28/2017] [Indexed: 12/13/2022] Open
Abstract
In clinical decision making, in addition to anatomical information, biomechanical properties of soft tissues may provide additional clues for disease diagnosis. Given the fact that most of diseases are originated from micron sized structures, an elastography imaging system of fine resolution (~100 µm) and deep penetration depth capable of providing both qualitative and quantitative measurements of biomechanical properties is desired. Here, we report a newly developed multi-functional ultrasonic micro-elastography imaging system in which acoustic radiation force impulse imaging (ARFI) and shear wave elasticity imaging (SWEI) are implemented. To accomplish this, the 4.5 MHz/40 MHz transducer were used as the excitation/detection source, respectively. The imaging system was tested with tissue-mimicking phantoms and an ex vivo chicken liver through 2D/3D imaging. The measured lateral/axial elastography resolution and field of view are 223.7 ± 20.1/109.8 ± 6.9 µm and 1.5 mm for ARFI, 543.6 ± 39.3/117.6 ± 8.7 µm and 2 mm for SWEI, respectively. These results demonstrate that the promising capability of this high resolution elastography imaging system for characterizing tissue biomechanical properties at microscale level and its translational potential into clinical practice.
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21
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Li GY, Cao Y. Mechanics of ultrasound elastography. Proc Math Phys Eng Sci 2017; 473:20160841. [PMID: 28413350 PMCID: PMC5378248 DOI: 10.1098/rspa.2016.0841] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/23/2017] [Indexed: 12/19/2022] Open
Abstract
Ultrasound elastography enables in vivo measurement of the mechanical properties of living soft tissues in a non-destructive and non-invasive manner and has attracted considerable interest for clinical use in recent years. Continuum mechanics plays an essential role in understanding and improving ultrasound-based elastography methods and is the main focus of this review. In particular, the mechanics theories involved in both static and dynamic elastography methods are surveyed. They may help understand the challenges in and opportunities for the practical applications of various ultrasound elastography methods to characterize the linear elastic, viscoelastic, anisotropic elastic and hyperelastic properties of both bulk and thin-walled soft materials, especially the in vivo characterization of biological soft tissues.
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Affiliation(s)
- Guo-Yang Li
- Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, AML, Tsinghua University, Beijing 100084, People's Republic of China
| | - Yanping Cao
- Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, AML, Tsinghua University, Beijing 100084, People's Republic of China
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22
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Palmeri ML, Qiang B, Chen S, Urban MW. Guidelines for Finite-Element Modeling of Acoustic Radiation Force-Induced Shear Wave Propagation in Tissue-Mimicking Media. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2017; 64:78-92. [PMID: 28026760 PMCID: PMC5310216 DOI: 10.1109/tuffc.2016.2641299] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ultrasound shear wave elastography is emerging as an important imaging modality for evaluating tissue material properties. In its practice, some systematic biases have been associated with ultrasound frequencies, focal depths and configuration, and transducer types (linear versus curvilinear), along with displacement estimation and shear wave speed estimation algorithms. Added to that, soft tissues are not purely elastic, so shear waves will travel at different speeds depending on their spectral content, which can be modulated by the acoustic radiation force (ARF) excitation focusing, duration, and the frequency-dependent stiffness of the tissue. To understand how these different acquisition and material property parameters may affect the measurements of shear wave velocity, the simulations of the propagation of shear waves generated by ARF excitations in viscoelastic media are a very important tool. This paper serves to provide an in-depth description of how these simulations are performed. The general scheme is broken into three components: 1) simulation of the 3-D ARF push beam; 2) applying that force distribution to a finite-element model; and 3) extraction of the motion data for post-processing. All three components will be described in detail and combined to create a simulation platform that is powerful for developing and testing algorithms for academic and industrial researchers involved in making quantitative shear-wave-based measurements of tissue material properties.
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23
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González-Salido N, Medina L, Camacho J. Full Angle Spatial Compound of ARFI images for breast cancer detection. ULTRASONICS 2016; 71:161-171. [PMID: 27362998 DOI: 10.1016/j.ultras.2016.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 06/06/2016] [Accepted: 06/07/2016] [Indexed: 06/06/2023]
Abstract
Automated ultrasound breast imaging would overcome most of the limitations that precludes conventional hand-held echography to be an effective screening method for breast cancer diagnosis. If a three dimensional (3D) ultrasound dataset is acquired without manual intervention of the technician, repeatability and patient follow-up could be improved. Furthermore, depending on the system configuration, resolution and contrast could be enhanced with regard to conventional echography, improving lesion detectability and evaluation. Having multiple modalities is another major advantage of these automated systems, currently under development by several research groups. Because of their circular structure, some of them include through-transmission measurements that allow constructing speed of sound and attenuation maps, which adds complementary information to the conventional reflectivity B-Mode image. This work addresses the implementation of the Acoustic Radiation Force Impulse (ARFI) imaging technique in a Full Angle Spatial Compound (FASC) automated breast imaging system. It is of particular interest because of the high specificity of ARFI for breast cancer diagnosis, by representing tissue elasticity differences rather than acoustic reflectivity. First, the image formation process is analyzed and a compounding strategy is proposed for ARFI-FASC. Then, experimental results with a prototype system and two gelatin phantoms are presented: Phantom A with a hard inclusion in a soft background, and phantom B with three soft inclusions in a hard background and with three steel needles. It is demonstrated that the full angle composition of ARFI images improves image quality, enhancing Contrast to Noise Ratio (CNR) from 4.9 to 20.6 and 3.6 to 13.5 in phantoms A and B respectively. Furthermore, this CNR increase improved detectability of small structures (needles) with regard to images obtained from a single location, in which image texture masked their presence.
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Affiliation(s)
| | - Luis Medina
- Department of Ultrasonic Sensors and Technology, ITEFI-CSIC, Madrid, Spain
| | - Jorge Camacho
- Department of Ultrasonic Sensors and Technology, ITEFI-CSIC, Madrid, Spain
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24
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Selzo MR, Moore CJ, Hossain MM, Palmeri ML, Gallippi CM. On the Quantitative Potential of Viscoelastic Response (VisR) Ultrasound Using the One-Dimensional Mass-Spring-Damper Model. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2016; 63:1276-87. [PMID: 27046848 PMCID: PMC5016215 DOI: 10.1109/tuffc.2016.2539323] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Viscoelastic response (VisR) ultrasound is an acoustic radiation force (ARF)-based imaging method that fits induced displacements to a one-dimensional (1-D) mass-spring-damper (MSD) model to estimate the ratio of viscous to elastic moduli, τ, in viscoelastic materials. Error in VisR τ estimation arises from inertia and acoustic displacement underestimation. These error sources are herein evaluated using finite-element method (FEM) simulations, error correction methods are developed, and corrected VisR τ estimates are compared with true simulated τ values to assess VisR's relevance to quantifying viscoelasticity. With regard to inertia, adding a mass term in series with the Voigt model, to achieve the MSD model, accounts for inertia due to tissue mass when ideal point force excitations are used. However, when volumetric ARF excitations are applied, the induced complex system inertia is not described by the single-degree-of-freedom MSD model, causing VisR to overestimate τ. Regarding acoustic displacement underestimation, associated deformation of ARF-induced displacement profiles further distorts VisR τ estimates. However, median error in VisR τ is reduced to approximately -10% using empirically derived error correction functions applied to simulated viscoelastic materials with viscous and elastic properties representative of tissue. The feasibility of corrected VisR imaging is then demonstrated in vivo in the rectus femoris muscle of an adult with no known neuromuscular disorders. These results suggest VisR's potential relevance to quantifying viscoelastic properties clinically.
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25
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Lipman SL, Rouze NC, Palmeri ML, Nightingale KR. Evaluating the Improvement in Shear Wave Speed Image Quality Using Multidimensional Directional Filters in the Presence of Reflection Artifacts. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2016; 63:1049-1063. [PMID: 28458448 PMCID: PMC5409160 DOI: 10.1109/tuffc.2016.2558662] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Shear waves propagating through interfaces where there is a change in stiffness cause reflected waves that can lead to artifacts in shear wave speed (SWS) reconstructions. Two-dimensional (2-D) directional filters are commonly used to reduce in-plane reflected waves; however, SWS artifacts arise from both in- and out-of-imaging-plane reflected waves. Herein, we introduce 3-D shear wave reconstruction methods as an extension of the previous 2-D estimation methods and quantify the reduction in image artifacts through the use of volumetric SWS monitoring and 4-D-directional filters. A Gaussian acoustic radiation force impulse excitation was simulated in phantoms with Young's modulus (E) of 3 kPa and a 5-mm spherical lesion with E = 6, 12, or 18.75 kPa. The 2-D-, 3-D-, and 4-D-directional filters were applied to the displacement profiles to reduce in-and out-of-plane reflected wave artifacts. Contrast-to-noise ratio and SWS bias within the lesion were calculated for each reconstructed SWS image to evaluate the image quality. For 2-D SWS image reconstructions, the 3-D-directional filters showed greater improvements in image quality than the 2-D filters, and the 4-D-directional filters showed marginal improvement over the 3-D filters. Although 4-D-directional filters can further reduce the impact of large magnitude out-of-plane reflection artifacts in SWS images, computational overhead and transducer costs to acquire 3-D data may outweigh the modest improvements in image quality. The 4-D-directional filters have the largest impact in reducing reflection artifacts in 3-D SWS volumes.
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26
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Lipman SL, Rouze NC, Palmeri ML, Nightingale KR. Evaluating the Improvement in Shear Wave Speed Image Quality Using Multidimensional Directional Filters in the Presence of Reflection Artifacts. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2016. [PMID: 28458448 DOI: 10.1109/tuffc.58] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Shear waves propagating through interfaces where there is a change in stiffness cause reflected waves that can lead to artifacts in shear wave speed (SWS) reconstructions. Two-dimensional (2-D) directional filters are commonly used to reduce in-plane reflected waves; however, SWS artifacts arise from both in- and out-of-imaging-plane reflected waves. Herein, we introduce 3-D shear wave reconstruction methods as an extension of the previous 2-D estimation methods and quantify the reduction in image artifacts through the use of volumetric SWS monitoring and 4-D-directional filters. A Gaussian acoustic radiation force impulse excitation was simulated in phantoms with Young's modulus (E) of 3 kPa and a 5-mm spherical lesion with E = 6, 12, or 18.75 kPa. The 2-D-, 3-D-, and 4-D-directional filters were applied to the displacement profiles to reduce in-and out-of-plane reflected wave artifacts. Contrast-to-noise ratio and SWS bias within the lesion were calculated for each reconstructed SWS image to evaluate the image quality. For 2-D SWS image reconstructions, the 3-D-directional filters showed greater improvements in image quality than the 2-D filters, and the 4-D-directional filters showed marginal improvement over the 3-D filters. Although 4-D-directional filters can further reduce the impact of large magnitude out-of-plane reflection artifacts in SWS images, computational overhead and transducer costs to acquire 3-D data may outweigh the modest improvements in image quality. The 4-D-directional filters have the largest impact in reducing reflection artifacts in 3-D SWS volumes.
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27
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Zhao X, Pelegri AA. A Bayesian approach for characterization of soft tissue viscoelasticity in acoustic radiation force imaging. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2016; 32:e02741. [PMID: 26255624 DOI: 10.1002/cnm.2741] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/27/2015] [Accepted: 08/04/2015] [Indexed: 06/04/2023]
Abstract
Biomechanical imaging techniques based on acoustic radiation force (ARF) have been developed to characterize the viscoelasticity of soft tissue by measuring the motion excited by ARF non-invasively. The unknown stress distribution in the region of excitation limits an accurate inverse characterization of soft tissue viscoelasticity, and single degree-of-freedom simplified models have been applied to solve the inverse problem approximately. In this study, the ARF-induced creep imaging is employed to estimate the time constant of a Voigt viscoelastic tissue model, and an inverse finite element (FE) characterization procedure based on a Bayesian formulation is presented. The Bayesian approach aims to estimate a reasonable quantification of the probability distributions of soft tissue mechanical properties in the presence of measurement noise and model parameter uncertainty. Gaussian process metamodeling is applied to provide a fast statistical approximation based on a small number of computationally expensive FE model runs. Numerical simulation results demonstrate that the Bayesian approach provides an efficient and practical estimation of the probability distributions of time constant in the ARF-induced creep imaging. In a comparison study with the single degree of freedom models, the Bayesian approach with FE models improves the estimation results even in the presence of large uncertainty levels of the model parameters.
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Affiliation(s)
- Xiaodong Zhao
- Department of Mechanical and Aerospace Engineering, Rutgers, the State University of New Jersey, 98 Brett Road, Piscataway, NJ, 08854-8058, USA
| | - Assimina A Pelegri
- Department of Mechanical and Aerospace Engineering, Rutgers, the State University of New Jersey, 98 Brett Road, Piscataway, NJ, 08854-8058, USA
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28
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Qiu W, Wang C, Xiao Y, Qian M, Zheng H. A new shear wave imaging system for ultrasound elastography. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:3847-50. [PMID: 26737133 DOI: 10.1109/embc.2015.7319233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ultrasound elastography is able to provide a non-invasive measurement of tissue elasticity properties. Shear wave imaging (SWI) technique is a quantitative method for tissue stiffness assessment. However, traditional SWI implementations cannot acquire 2D quantitative images of tissue elasticity distribution. In this study, a new shear wave imaging system is proposed and evaluated. Detailed delineation of hardware and image processing algorithms are presented. Programmable devices are selected to support flexible control of the system and the image processing algorithms. Analytic signal based cross-correlation method and a Radon transform based shear wave speed determination method are proposed with parallel computation ability. Tissue mimicking phantom imaging, and in vitro imaging measurements are conducted to demonstrate the performance of the proposed system. The system has the ability to provide a new choice for quantitative mapping of the tissue elasticity, and has good potential to be implemented into commercial ultrasound scanner.
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29
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Qiu W, Wang C, Li Y, Zhou J, Yang G, Xiao Y, Feng G, Jin Q, Mu P, Qian M, Zheng H. A scanning-mode 2D shear wave imaging (s2D-SWI) system for ultrasound elastography. ULTRASONICS 2015; 62:89-96. [PMID: 26025508 DOI: 10.1016/j.ultras.2015.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Revised: 05/02/2015] [Accepted: 05/14/2015] [Indexed: 06/04/2023]
Abstract
Ultrasound elastography is widely used for the non-invasive measurement of tissue elasticity properties. Shear wave imaging (SWI) is a quantitative method for assessing tissue stiffness. SWI has been demonstrated to be less operator dependent than quasi-static elastography, and has the ability to acquire quantitative elasticity information in contrast with acoustic radiation force impulse (ARFI) imaging. However, traditional SWI implementations cannot acquire two dimensional (2D) quantitative images of the tissue elasticity distribution. This study proposes and evaluates a scanning-mode 2D SWI (s2D-SWI) system. The hardware and image processing algorithms are presented in detail. Programmable devices are used to support flexible control of the system and the image processing algorithms. An analytic signal based cross-correlation method and a Radon transformation based shear wave speed determination method are proposed, which can be implemented using parallel computation. Imaging of tissue mimicking phantoms, and in vitro, and in vivo imaging test are conducted to demonstrate the performance of the proposed system. The s2D-SWI system represents a new choice for the quantitative mapping of tissue elasticity, and has great potential for implementation in commercial ultrasound scanners.
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Affiliation(s)
- Weibao Qiu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
| | - Congzhi Wang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Yongchuan Li
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Juan Zhou
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Ge Yang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Yang Xiao
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Ge Feng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Qiaofeng Jin
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Peitian Mu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Ming Qian
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
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Ohmaru T, Fujita Y, Sugitani M, Shimokawa M, Fukushima K, Kato K. Placental elasticity evaluation using virtual touch tissue quantification during pregnancy. Placenta 2015; 36:915-20. [PMID: 26149518 DOI: 10.1016/j.placenta.2015.06.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/15/2015] [Accepted: 06/16/2015] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Virtual touch tissue quantification (VTTQ) has been developed to evaluate tissue elasticity. Our previous study using delivered placentas showed increased elasticity in fetal growth restriction (FGR). Therefore, we investigated changes in placental elasticity during pregnancy, including complicated pregnancies. METHODS Based on complications, 199 women were divided into 5 groups (normal, FGR, pregnancy induced hypertension (PIH), diabetes mellitus and collagen disease), and shear wave velocity (SWV) of the placenta, measured using VTTQ, was compared. A cross-sectional study was performed with the 143 normal cases to construct the reference range. The association between placental SWV and the expression ratio of collagen fibers in the placenta stained with Masson's trichrome was determined. RESULTS The SWV was safely measured for all participants. The correlation between SWV and gestational weeks was not significant. The mean ± SD SWVs in the normal, FGR, and PIH groups were 0.98 ± 0.21, 1.28 ± 0.39, and 1.60 ± 0.45 m/sec, respectively. The FGR and PIH groups had significantly higher SWVs than that of the normal group. SWV and the expression ratio of collagen fibers were significantly correlated. DISCUSSION Based on the present findings, changes in SWV during pregnancy were associated with placental fibrosis, and increased SWV in PIH and/or FGR cases might be influenced by infarction, ischemic changes, and inflammation, as well as fibrosis. In conclusion, the measurement of placental SWV is potentially useful to evaluate the condition of the placenta during pregnancy.
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Affiliation(s)
- Takako Ohmaru
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yasuyuki Fujita
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
| | - Maiko Sugitani
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Mototsugu Shimokawa
- Department of Cancer Information Research, Clinical Research Institute, National Kyushu Cancer Center, Fukuoka, Japan
| | - Kotaro Fukushima
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kiyoko Kato
- Department of Obstetrics and Gynecology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Zhang X, Miller RM, Lin KW, Levin AM, Owens GE, Gurm HS, Cain CA, Xu Z. Real-time feedback of histotripsy thrombolysis using bubble-induced color Doppler. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:1386-401. [PMID: 25623821 PMCID: PMC4398659 DOI: 10.1016/j.ultrasmedbio.2014.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 11/25/2014] [Accepted: 12/10/2014] [Indexed: 05/06/2023]
Abstract
Histotripsy thrombolysis is a non-invasive, drug-free, image-guided therapy that fractionates blood clots using well-controlled acoustic cavitation alone. Real-time quantitative feedback is highly desired during histotripsy thrombolysis treatment to monitor the progress of clot fractionation. Bubble-induced color Doppler (BCD) monitors the motion after cavitation generated by each histotripsy pulse, which has been found in gel and ex vivo liver tissue to be correlated with histotripsy fractionation. We investigated the potential of BCD to quantitatively monitor histotripsy thrombolysis in real time. To visualize clot fractionation, transparent three-layered fibrin clots were developed. Results indicated that a coherent motion follows the cavitation generated by each histotripsy pulse with a push and rebound pattern. The temporal profile of this motion expands and saturates as treatment progresses. A strong correlation exists between the degree of histotripsy clot fractionation and two metrics extracted from BCD: time of peak rebound velocity (tPRV) and focal mean velocity at a fixed delay (Vf,delay). The saturation of clot fractionation (i.e., treatment completion) matches well the saturations detected using tPRV and Vf,delay. The mean Pearson correlation coefficients between the progression of clot fractionation and the two BCD metrics were 93.1% and 92.6%, respectively. To validate BCD feedback in in vitro clots, debris volumes from histotripsy thrombolysis were obtained at different therapy doses and compared with Vf,delay. There is also good agreement between the increasing and saturation trends of debris volume and Vf,delay. Finally, a real-time BCD feedback algorithm to predict complete clot fractionation during histotripsy thrombolysis was developed and tested. This work illustrates the potential of BCD to monitor histotripsy thrombolysis treatment in real time.
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Affiliation(s)
- Xi Zhang
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA.
| | - Ryan M Miller
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Kuang-Wei Lin
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Albert M Levin
- Department of Public Health Sciences, Henry Ford Health System, Detroit, Michigan, USA
| | - Gabe E Owens
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA; Division of Pediatric Cardiology, Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, USA
| | - Hitinder S Gurm
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Charles A Cain
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Zhen Xu
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, USA; Division of Pediatric Cardiology, Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, USA
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Hollender PJ, Rosenzweig SJ, Nightingale KR, Trahey GE. Single- and multiple-track-location shear wave and acoustic radiation force impulse imaging: matched comparison of contrast, contrast-to-noise ratio and resolution. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:1043-57. [PMID: 25701531 PMCID: PMC4346467 DOI: 10.1016/j.ultrasmedbio.2014.11.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 11/03/2014] [Accepted: 11/08/2014] [Indexed: 05/03/2023]
Abstract
Acoustic radiation force impulse imaging and shear wave elasticity imaging (SWEI) use the dynamic response of tissue to impulsive mechanical stimulus to characterize local elasticity. A variant of conventional, multiple-track-location SWEI, denoted single-track-location SWEI, offers the promise of creating speckle-free shear wave images. This work compares the three imaging modalities using a high push and track beam density combined acquisition sequence to image inclusions of different sizes and contrasts. Single-track-location SWEI is found to have a significantly higher contrast-to-noise ratio than multiple-track-location SWEI, allowing for operation at higher resolution. Acoustic radiation force impulse imaging and single-track-location SWEI perform similarly in the larger inclusions, with single-track-location SWEI providing better visualization of small targets ≤ 2.5 mm in diameter. The processing of each modality introduces different trade-offs between smoothness and resolution of edges and structures; these are discussed in detail.
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Affiliation(s)
- Peter J Hollender
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA.
| | - Stephen J Rosenzweig
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | | | - Gregg E Trahey
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA; Department of Radiology, Duke University, Durham, North Carolina, USA
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Caenen A, Shcherbakova D, Verhegghe B, Papadacci C, Pernot M, Segers P, Swillens A. A versatile and experimentally validated finite element model to assess the accuracy of shear wave elastography in a bounded viscoelastic medium. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:439-450. [PMID: 25768813 DOI: 10.1109/tuffc.2014.006682] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The feasibility of shear wave elastography (SWE) in arteries for cardiovascular risk assessment remains to be investigated as the artery's thin wall and intricate material properties induce complex shear wave (SW) propagation phenomena. To better understand the SW physics in bounded media, we proposed an in vitro validated finite element model capable of simulating SW propagation, with full flexibility at the level of the tissue's geometry, material properties, and acoustic radiation force. This computer model was presented in a relatively basic set-up, a homogeneous slab of gelatin-agar material (4.35 mm thick), allowing validation of the numerical settings according to actual SWE measurements. The resulting tissue velocity waveforms and SW propagation speed matched well with the measurement: 4.46 m/s (simulation) versus 4.63 ± 0.07 m/s (experiment). Further, we identified the impact of geometrical and material parameters on the SW propagation characteristics. As expected, phantom thickness was a determining factor of dispersion. Adding viscoelasticity to the model augmented the estimated wave speed to 4.58 m/s, an even better match with the experimental determined value. This study demonstrated that finite element modeling can be a powerful tool to gain insight into SWE mechanics and will in future work be advanced to more clinically relevant settings.
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Czernuszewicz TJ, Homeister JW, Caughey MC, Farber MA, Fulton JJ, Ford PF, Marston WA, Vallabhaneni R, Nichols TC, Gallippi CM. Non-invasive in vivo characterization of human carotid plaques with acoustic radiation force impulse ultrasound: comparison with histology after endarterectomy. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:685-97. [PMID: 25619778 PMCID: PMC4331250 DOI: 10.1016/j.ultrasmedbio.2014.09.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 08/30/2014] [Accepted: 09/10/2014] [Indexed: 05/03/2023]
Abstract
Ischemic stroke from thromboembolic sources is linked to carotid artery atherosclerotic disease with a trend toward medical management in asymptomatic patients. Extent of disease is currently diagnosed by non-invasive imaging techniques that measure luminal stenosis, but it has been suggested that a better biomarker for determining risk of future thromboembolic events is plaque morphology and composition. Specifically, plaques that are composed of mechanically soft lipid/necrotic regions covered by thin fibrous caps are the most vulnerable to rupture. An ultrasound technique that non-invasively interrogates the mechanical properties of soft tissue, called acoustic radiation force impulse (ARFI) imaging, has been developed as a new modality for atherosclerotic plaque characterization using phantoms and atherosclerotic pigs, but the technique has yet to be validated in vivo in humans. In this preliminary study, in vivo ARFI imaging is presented in a case study format for four patients undergoing clinically indicated carotid endarterectomy and compared with histology. In two type Va plaques, characterized by lipid/necrotic cores covered by fibrous caps, mean ARFI displacements in focal regions were high relative to the surrounding plaque material, suggesting soft features were covered by stiffer layers within the plaques. In two type Vb plaques, characterized by heavy calcification, mean ARFI peak displacements were low relative to the surrounding plaque and arterial wall, suggesting stiff tissue. This pilot study illustrates the feasibility and challenges of transcutaneous ARFI for characterizing the material and structural composition of carotid atherosclerotic plaques via mechanical properties, in humans, in vivo.
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Affiliation(s)
- Tomasz J Czernuszewicz
- Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, North Carolina, USA
| | - Jonathon W Homeister
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina, USA; McAllister Heart Institute, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Melissa C Caughey
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Mark A Farber
- Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Joseph J Fulton
- Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Peter F Ford
- Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA
| | - William A Marston
- Department of Surgery, University of North Carolina, Chapel Hill, North Carolina, USA
| | | | - Timothy C Nichols
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina, USA; Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Caterina M Gallippi
- McAllister Heart Institute, University of North Carolina, Chapel Hill, North Carolina, USA; Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina, USA; Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, North Carolina, USA.
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35
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Zhao X, Pelegri AA. Dynamic simulation of viscoelastic soft tissue in acoustic radiation force creep imaging. J Biomech Eng 2015; 136:094502. [PMID: 24975997 DOI: 10.1115/1.4027934] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 07/01/2014] [Indexed: 11/08/2022]
Abstract
Acoustic radiation force (ARF) creep imaging applies step ARF excitation to induce creep displacement of soft tissue, and the corresponding time-dependent responses are used to estimate soft tissue viscoelasticity or its contrast. Single degree of freedom (SDF) and homogeneous analytical models have been used to characterize soft tissue viscoelasticity in ARF creep imaging. The purpose of this study is to investigate the fundamental limitations of the commonly used SDF and homogeneous assumptions in ARF creep imaging. In this paper, finite element (FE) models are developed to simulate the dynamic behavior of viscoelastic soft tissue subjected to step ARF. Both homogeneous and heterogeneous models are studied with different soft tissue viscoelasticity and ARF configurations. The results indicate that the SDF model can provide good estimations for homogeneous soft tissue with high viscosity, but exhibits poor performance for low viscosity soft tissue. In addition, a smaller focal region of the ARF is desirable to reduce the estimation error with the SDF models. For heterogeneous media, the responses of the focal region are highly affected by the local heterogeneity, which results in deterioration of the effectiveness of the SDF and homogeneous simplifications.
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36
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Zhu B, Witzel T, Jiang S, Huang SY, Rosen BR, Wald LL. Selective magnetic resonance imaging of magnetic nanoparticles by acoustically induced rotary saturation. Magn Reson Med 2014; 75:97-106. [PMID: 25537578 DOI: 10.1002/mrm.25522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 09/14/2014] [Accepted: 10/17/2014] [Indexed: 12/21/2022]
Abstract
PURPOSE The goal of this study was to introduce a new method to selectively detect iron oxide contrast agents using an acoustic wave to perturb the spin-locked water signal in the vicinity of the magnetic particles. The acoustic drive can be modulated externally to turn the effect on and off, allowing sensitive and quantitative statistical comparison and removal of confounding image background variations. METHODS We demonstrated the effect in spin-locking experiments using piezoelectric actuators to generate vibrational displacements of iron oxide samples. We observed a resonant behavior of the signal changes with respect to the acoustic frequency where iron oxide is present. We characterized the effect as a function of actuator displacement and contrast agent concentration. RESULTS The resonant effect allowed us to generate block-design "modulation response maps" indicating the contrast agent's location, as well as positive contrast images with suppressed background signal. We found that the acoustically induced rotary saturation (AIRS) effect stayed approximately constant across acoustic frequency and behaved monotonically over actuator displacement and contrast agent concentration. CONCLUSION AIRS is a promising method capable of using acoustic vibrations to modulate the contrast from iron oxide nanoparticles and thus perform selective detection of the contrast agents, potentially enabling more accurate visualization of contrast agents in clinical and research settings.
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Affiliation(s)
- Bo Zhu
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard-MIT Division of Health Sciences Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Thomas Witzel
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Shan Jiang
- David H Koch Institute for Integrative Cancer Research, Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Susie Y Huang
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Bruce R Rosen
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Department of Meridian & Acupuncture, Collaborating Center for Traditional Medicine, East-West Medical Research Institute and School of Korean Medicine, Kyung Hee University, Seoul, Republic of Korea.,Harvard-MIT Division of Health Sciences Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Lawrence L Wald
- Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Harvard-MIT Division of Health Sciences Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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Zhu Y, Zhang X, Zheng Y, Chen X, Shen Y, Lin H, Guo Y, Wang T, Chen S. Quantitative analysis of liver fibrosis in rats with shearwave dispersion ultrasound vibrometry: comparison with dynamic mechanical analysis. Med Eng Phys 2014; 36:1401-7. [PMID: 24835187 DOI: 10.1016/j.medengphy.2014.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 04/02/2014] [Accepted: 04/04/2014] [Indexed: 12/19/2022]
Abstract
Ultrasonic elastography, a non-invasive technique for assessing the elasticity properties of tissues, has shown promising results for disease diagnosis. However, biological soft tissues are viscoelastic in nature. Shearwave dispersion ultrasound vibrometry (SDUV) can simultaneously measure the elasticity and viscosity of tissue using shear wave propagation speeds at different frequencies. In this paper, the viscoelasticity of rat livers was measured quantitatively by SDUV for normal (stage F0) and fibrotic livers (stage F2). Meanwhile, an independent validation study was presented in which SDUV results were compared with those derived from dynamic mechanical analysis (DMA), which is the only mechanical test that simultaneously assesses the viscoelastic properties of tissue. Shear wave speeds were measured at frequencies of 100, 200, 300 and 400 Hz with SDUV and the storage moduli and loss moduli were measured at the frequency range of 1-40 Hz with DMA. The Voigt viscoelastic model was used in the two methods. The mean elasticity and viscosity obtained by SDUV ranged from 0.84±0.13 kPa (F0) to 1.85±0.30 kPa (F2) and from 1.12±0.11 Pa s (F0) to 1.70±0.31 Pa s (F2), respectively. The mean elasticity and viscosity derived from DMA ranged from 0.62±0.09 kPa (F0) to 1.70±0.84 kPa (F2) and from 3.38±0.32 Pa s (F0) to 4.63±1.30 Pa s (F2), respectively. Both SDUV and DMA demonstrated that the elasticity of rat livers increased from stage F0 to F2, a finding which was consistent with previous literature. However, the elasticity measurements obtained by SDUV had smaller differences than those obtained by DMA, whereas the viscosities obtained by the two methods were obviously different. We suggest that the difference could be related to factors such as tissue microstructure, the frequency range, sample size and the rheological model employed. For future work we propose some improvements in the comparative tests between SDUV and DMA, such as enlarging the harmonic frequency range of the shear wave to highlight the role of viscosity, finding an appropriate rheological model to improve the accuracy of tissue viscoelasticity estimations.
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Affiliation(s)
- Ying Zhu
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Xinyu Zhang
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Yi Zheng
- Department of Electrical and Computer Engineering, St. Cloud State University, St. Cloud, MN 56301, USA
| | - Xin Chen
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Yuanyuan Shen
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Haoming Lin
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Yanrong Guo
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Tianfu Wang
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China
| | - Siping Chen
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, School of Medicine, Shenzhen University, Shenzhen 518160, China.
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Eyerly SA, Bahnson TD, Koontz JI, Bradway DP, Dumont DM, Trahey GE, Wolf PD. Contrast in intracardiac acoustic radiation force impulse images of radiofrequency ablation lesions. ULTRASONIC IMAGING 2014; 36:133-48. [PMID: 24554293 PMCID: PMC4049337 DOI: 10.1177/0161734613519602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 ± 1.71 µm) than at ablated sites (6.06 ± 0.94 µm). The average lesion C (0.29 ± 0.33) and CNR (1.83 ± 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = -0.03 ± 0.28, CNR = 0.74 ± 0.68).
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Affiliation(s)
| | - Tristram D. Bahnson
- Duke Center for Atrial Fibrillation, Duke Heart Center, and Clinical Cardiac Electrophysiology Section of the Division of Cardiovascular Medicine, Duke University, Durham, NC, USA
| | - Jason I. Koontz
- Duke Center for Atrial Fibrillation, Duke Heart Center, and Clinical Cardiac Electrophysiology Section of the Division of Cardiovascular Medicine, Duke University, Durham, NC, USA
| | - David P. Bradway
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Douglas M. Dumont
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Gregg E. Trahey
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Patrick D. Wolf
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Razani M, Luk TW, Mariampillai A, Siegler P, Kiehl TR, Kolios MC, Yang VX. Optical coherence tomography detection of shear wave propagation in inhomogeneous tissue equivalent phantoms and ex-vivo carotid artery samples. BIOMEDICAL OPTICS EXPRESS 2014; 5:895-906. [PMID: 24688822 PMCID: PMC3959849 DOI: 10.1364/boe.5.000895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/16/2014] [Accepted: 02/19/2014] [Indexed: 05/04/2023]
Abstract
In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) in an inhomogeneous phantom and carotid artery samples based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 μs duration, applying acoustic radiation force (ARF) to inhomogeneous phantoms and carotid artery samples, synchronized with a swept-source OCT (SS-OCT) imaging system. The phantoms were composed of gelatin and titanium dioxide whereas the carotid artery samples were embedded in gel. Differential OCT phase maps, measured with and without the ARF, detected the microscopic displacement generated by shear wave propagation in these phantoms and samples of different stiffness. We present the technique for calculating tissue mechanical properties by propagating shear waves in inhomogeneous tissue equivalent phantoms and carotid artery samples using the ARF of an ultrasound transducer, and measuring the shear wave speed and its associated properties in the different layers with OCT phase maps. This method lays the foundation for future in-vitro and in-vivo studies of mechanical property measurements of biological tissues such as vascular tissues, where normal and pathological structures may exhibit significant contrast in the shear modulus.
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Affiliation(s)
- Marjan Razani
- Department of Physics, Ryerson University, Toronto, Canada
| | - Timothy W.H. Luk
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
| | - Adrian Mariampillai
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
| | - Peter Siegler
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
| | - Tim-Rasmus Kiehl
- Department of Pathology, University Health Network, Toronto, Ontario Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
| | | | - Victor X.D. Yang
- Department of Physics, Ryerson University, Toronto, Canada
- Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada
- Division of Neurosurgery, University of Toronto, Toronto, Canada
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Montagnon E, Hadj-Henni A, Schmitt C, Cloutier G. Rheological assessment of a polymeric spherical structure using a three-dimensional shear wave scattering model in dynamic spectroscopy elastography. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2014; 61:277-287. [PMID: 24474134 DOI: 10.1109/tuffc.2014.6722613] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
With the purpose of assessing localized rheological behavior of pathological tissues using ultrasound dynamic elastography, an analytical shear wave scattering model was used in an inverse problem framework. The proposed method was adopted to estimate the complex shear modulus of viscoelastic spheres from 200 to 450 Hz. The inverse problem was formulated and solved in the frequency domain, allowing assessment of the complex viscoelastic shear modulus at discrete frequencies. A representative rheological model of the spherical obstacle was determined by comparing storage and loss modulus behaviors with Kelvin-Voigt, Maxwell, Zener, and Jeffrey models. The proposed inversion method was validated by using an external vibrating source and acoustic radiation force. The estimation of viscoelastic properties of three-dimensional spheres made softer or harder than surrounding tissues did not require a priori rheological assumptions. The proposed method is intended to be applied in the context of breast cancer imaging.
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Selzo MR, Gallippi CM. Viscoelastic response (VisR) imaging for assessment of viscoelasticity in Voigt materials. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:2488-500. [PMID: 24297015 PMCID: PMC4164206 DOI: 10.1109/tuffc.2013.2848] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Viscoelastic response (VisR) imaging is presented as a new acoustic radiation force (ARF)-based elastographic imaging method. Exploiting the Voigt model, VisR imaging estimates displacement in only the ARF region of excitation from one or two successive ARF impulses to estimate τσ, the relaxation time for constant stress. Double-push VisR τσ estimates were not statistically significantly different (p < 0.02) from those of shearwave dispersion ultrasound vibrometry (SDUV) or monitored steady-state excitation recovery (MSSER) ultrasound in six homogeneous viscoelastic tissue mimicking phantoms with elastic moduli ranging from 3.92 to 15.34 kPa and coefficients of viscosity ranging from 0.87 to 14.06 Pa·s. In two-dimensional imaging, double-push VisR τσ images discriminated a viscous spherical inclusion in a structured phantom with higher CNR over a larger axial range than single-push VisR or conventional acoustic radiation force impulse (ARFI) ultrasound. Finally, 2-D in vivo double-push VisR images in normal canine semitendinosus muscle were compared with spatially matched histochemistry to corroborate lower double-push VisR τσ values in highly collagenated connective tissue than in muscle, suggesting double-push VisR's in vivo relevance to diagnostic imaging, particularly in muscle. The key advantages and disadvantages to VisR, including lack of compensation for inertial terms, are discussed.
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Behler RH, Czernuszewicz TJ, Wu CD, Nichols TC, Zhu H, Homeister JW, Merricks EP, Gallippi CM. Acoustic radiation force beam sequence performance for detection and material characterization of atherosclerotic plaques: preclinical, ex vivo results. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:2471-87. [PMID: 24297014 PMCID: PMC4097991 DOI: 10.1109/tuffc.2013.2847] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
This work presents preclinical data demonstrating performance of acoustic radiation force (ARF)-based elasticity imaging with five different beam sequences for atherosclerotic plaque detection and material characterization. Twelve trained, blinded readers evaluated parametric images taken ex vivo under simulated in vivo conditions of 22 porcine femoral arterial segments. Receiver operating characteristic (ROC) curve analysis was carried out to quantify reader performance using spatially-matched immunohistochemistry for validation. The beam sequences employed had high sensitivity (sens) and specificity (spec) for detecting Type III+ plaques (sens: 85%, spec: 79%), lipid pools (sens: 80%, spec: 86%), fibrous caps (sens: 86%, spec: 82%), calcium (sens: 96%, spec: 85%), collagen (sens: 78%, spec: 77%), and disrupted internal elastic lamina (sens: 92%, spec: 75%). 1:1 single-receive tracking yielded the highest median areas under the ROC curve (AUC), but was not statistically significantly higher than 4:1 parallel-receive tracking. Excitation focal configuration did not result in statistically different AUCs. Overall, these results suggest ARF-based imaging is relevant to detecting and characterizing plaques and support its use for diagnosing and monitoring atherosclerosis.
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Scola MR, Baggesen LM, Gallippi CM. Multi-push (MP) acoustic radiation force (ARF) ultrasound for assessing tissue viscoelasticity, in vivo. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:2323-6. [PMID: 23366389 DOI: 10.1109/embc.2012.6346428] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Acoustic radiation force (ARF) ultrasound is a method of elastographic imaging in which micron-scale tissue displacements, induced and tracked by ultrasound, reflect clinically relevant tissue mechanical properties. Our laboratory has recently shown that tissue viscoelasticity is assessed using the novel Multi-Push (MP) ARF method. MP ARF applies the Voigt model for viscoelastic materials and compares the displacements achieved by successive ARF excitations to qualitatively or quantitatively represent the relaxation time for constant stress, which is a direct descriptor of the viscoelastic response of the tissue. We have demonstrated MP ARF in custom viscoelastic tissue mimicking materials and implemented the method in vivo in canine muscle and human renal allografts, with strong spatial correlation between MP ARF findings and histochemical features and previously reported mechanical changes with renal disease. These data support that noninvasive MP ARF is capable of clinically relevant assessment of tissue viscoelastic properties.
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Czernuszewicz TJ, Streeter JE, Dayton PA, Gallippi CM. Experimental validation of displacement underestimation in ARFI ultrasound. ULTRASONIC IMAGING 2013; 35:196-213. [PMID: 23858054 PMCID: PMC4097970 DOI: 10.1177/0161734613493262] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Acoustic radiation force impulse (ARFI) imaging is an elastography technique that uses ultrasonic pulses to displace and track tissue motion. Previous modeling studies have shown that ARFI displacements are susceptible to underestimation due to lateral and elevational shearing that occurs within the tracking resolution cell. In this study, optical tracking was utilized to experimentally measure the displacement underestimation achieved by acoustic tracking using a clinical ultrasound system. Three optically translucent phantoms of varying stiffness were created, embedded with subwavelength diameter microspheres, and ARFI excitation pulses with F/1.5 or F/3 lateral focal configurations were transmitted from a standard linear array to induce phantom motion. Displacements were tracked using confocal optical and acoustic methods. As predicted by earlier finite element method studies, significant acoustic displacement underestimation was observed for both excitation focal configurations; the maximum underestimation error was 35% of the optically measured displacement for the F/1.5 excitation pulse in the softest phantom. Using higher F/#, less tightly focused beams in the lateral dimension improved accuracy of displacements by approximately 10 percentage points. This work experimentally demonstrates limitations of ARFI implemented on a clinical scanner using a standard linear array and sets up a framework for future displacement tracking validation studies.
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Affiliation(s)
| | | | | | - Caterina M. Gallippi
- Corresponding author Phone: (919) 843-6647 Address: 152 Macnider Campus Box 7575 Chapel Hill, NC 27519 USA
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Shih CC, Huang CC, Zhou Q, Shung KK. High-resolution acoustic-radiation-force-impulse imaging for assessing corneal sclerosis. IEEE TRANSACTIONS ON MEDICAL IMAGING 2013; 32:1316-24. [PMID: 23584258 PMCID: PMC3760240 DOI: 10.1109/tmi.2013.2256794] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In ophthalmology, detecting the biomechanical properties of the cornea can provide valuable information about various corneal pathologies, including keratoconus and the phototoxic effects of ultraviolet radiation on the cornea. Also, the mechanical properties of the cornea can be used to evaluate the recovery from corneal refractive surgeries. Therefore, noninvasive and high-resolution estimation of the stiffness distribution in the cornea is important in ophthalmic diagnosis. The present study established a method for high-resolution acoustic-radiation-force-impulse (ARFI) imaging based on a dual-frequency confocal transducer in order to obtain a relative stiffness map, which was used to assess corneal sclerosis. An 11-MHz pushing element was used to induce localized displacements of tissue, which were monitored by a 48-MHz imaging element. Since the tissue displacements are directly correlated with the tissue elastic properties, the stiffness distribution in a tiny region of the cornea can be found by a mechanical B/D scan. The experimental system was verified using tissue-mimicking phantoms that included different geometric structures. Ex vivo cornea experiments were carried out using fresh porcine eyeballs. Corneas with localized sclerosis were created artificially by the injection of a formalin solution. The phantom experiments showed that the distributions of stiffness within different phantoms can be recognized clearly using ARFI imaging, and the measured lateral and axial resolutions of this imaging system were 177 and 153 μ m, respectively. The ex vivo experimental results from ARFI imaging showed that a tiny region of localized sclerosis in the cornea could be distinguished. All of the obtained results demonstrate that high-resolution ARFI imaging has considerable potential for the clinical diagnosis of corneal sclerosis.
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Affiliation(s)
- Cho-Chiang Shih
- Department of Electrical Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan, and also with the Graduate Institute of Applied Science and Engineering, Fu Jen Catholic University, New Taipei City 24205, Taiwan
| | - Chih-Chung Huang
- Department of Biomedical Engineering, National Cheng Kung University, Tainan City 701, Taiwan ()
| | - Qifa Zhou
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089 USA
| | - K. Kirk Shung
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089 USA
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Doherty JR, Trahey GE, Nightingale KR, Palmeri ML. Acoustic radiation force elasticity imaging in diagnostic ultrasound. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2013; 60:685-701. [PMID: 23549529 PMCID: PMC3679553 DOI: 10.1109/tuffc.2013.2617] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The development of ultrasound-based elasticity imaging methods has been the focus of intense research activity since the mid-1990s. In characterizing the mechanical properties of soft tissues, these techniques image an entirely new subset of tissue properties that cannot be derived with conventional ultrasound techniques. Clinically, tissue elasticity is known to be associated with pathological condition and with the ability to image these features in vivo; elasticity imaging methods may prove to be invaluable tools for the diagnosis and/or monitoring of disease. This review focuses on ultrasound-based elasticity imaging methods that generate an acoustic radiation force to induce tissue displacements. These methods can be performed noninvasively during routine exams to provide either qualitative or quantitative metrics of tissue elasticity. A brief overview of soft tissue mechanics relevant to elasticity imaging is provided, including a derivation of acoustic radiation force, and an overview of the various acoustic radiation force elasticity imaging methods.
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Affiliation(s)
- Joshua R Doherty
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
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Dewall RJ, Varghese T, Brace CL. Visualizing ex vivo radiofrequency and microwave ablation zones using electrode vibration elastography. Med Phys 2013; 39:6692-700. [PMID: 23127063 DOI: 10.1118/1.4758061] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
PURPOSE Electrode vibration elastography is a new shear wave imaging technique that can be used to visualize thermal ablation zones. Prior work has shown the ability of electrode vibration elastography to delineate radiofrequency ablations; however, there has been no previous study of delineation of microwave ablations or radiological-pathological correlations using multiple observers. METHODS Radiofrequency and microwave ablations were formed in ex vivo bovine liver tissue. Their visualization was compared on shear wave velocity and maximum displacement images. Ablation dimensions were compared to gross pathology. Elastographic imaging and gross pathology overlap and interobserver variability were quantified using similarity measures. RESULTS Elastographic imaging correlated with gross pathology. Correlation of area estimates was better in radiofrequency than in microwave ablations, with Pearson coefficients of 0.79 and 0.54 on shear wave velocity images and 0.90 and 0.70 on maximum displacement images for radiofrequency and microwave ablations, respectively. The absolute relative difference in area between elastographic imaging and gross pathology was 18.9% and 22.9% on shear wave velocity images and 16.0% and 23.1% on maximum displacement images for radiofrequency and microwave ablations, respectively. CONCLUSIONS Statistically significant radiological-pathological correlation was observed in this study, but correlation coefficients were lower than other modulus imaging techniques, most notably in microwave ablations. Observers provided similar delineations for most thermal ablations. These results suggest that electrode vibration elastography is capable of imaging thermal ablations, but refinement of the technique may be necessary before it can be used to monitor thermal ablation procedures clinically.
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Affiliation(s)
- Ryan J Dewall
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA.
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Doherty JR, Dumont DM, Trahey GE, Palmeri ML. Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis. J Biomech 2012; 46:83-90. [PMID: 23122224 DOI: 10.1016/j.jbiomech.2012.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 09/22/2012] [Accepted: 10/04/2012] [Indexed: 10/27/2022]
Abstract
Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI imaging could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was<1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI imaging are orders of magnitude lower than the stresses associated with blood pressure.
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Affiliation(s)
- Joshua R Doherty
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
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Yamanaka N, Kaminuma C, Taketomi-Takahashi A, Tsushima Y. Reliable measurement by virtual touch tissue quantification with acoustic radiation force impulse imaging: phantom study. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2012; 31:1239-1244. [PMID: 22837288 DOI: 10.7863/jum.2012.31.8.1239] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVES The purpose of this study was to evaluate the factors that may affect shear wave velocity (SWV) measurements by using a phantom. METHODS The SWVs (meters per second) of 4 phantom targets and background, each of different hardness (Young modulus, 8-80 kPa), were measured in the virtual touch tissue quantification mode. Ten SWV measurements were performed on each target, and the mean SWV and its standard deviation were calculated. To assess the effect of the distance between the probe and region of interest (ROI) settings, mean SWV measurements of the background at 5 to 80 mm in depth were performed with a convex probe and at 5 to 40 mm with a high-frequency linear probe. RESULTS The linear correlation between the nominal Young modulus of the phantom and those calculated from the mean SWV was highly significant for the linear probe (y = 0.98x - 0.70; r(2) = 0.99; P = .0007). For the convex probe, the linear correlation between the nominal Young modulus of the phantom and those calculated from the mean SWV was highly significant between 8 and 40 kPa (y =1.26x + 1.01; r(2) = 0.98; P = .011). Measurement variations for the linear probe were little influenced by the distance between the probe and ROI, but those for the convex probe were dependent on the distance. CONCLUSIONS The accuracy of the mean SWV measurement was dependent on the probe used and the distance between the probe and ROI settings. The linear probe provides accurate measurements throughout its range for all but its deepest limit. Measurements of 40 mm or deeper are better performed with a convex probe. Probe selection should be based on individual lesion depth.
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Affiliation(s)
- Noriko Yamanaka
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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Dhanaliwala A.H, Hossack JA, Mauldin FW. Assessing and improving acoustic radiation force image quality using a 1.5-D transducer design. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2012; 59:1602-8. [PMID: 22828855 PMCID: PMC4047991 DOI: 10.1109/tuffc.2012.2360] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A 1.5-D transducer array was proposed to improve acoustic radiation force impulse (ARFI) imaging signal-to-noise ratio (SNRARFI) and image contrast relative to a conventional 1-D array. To predict performance gains from the proposed 1.5-D transducer array, an analytical model for SNRARFI upper bound was derived. The analytical model and 1.5-D ARFI array were validated using a finite element modelbased numerical simulation framework. The analytical model demonstrated good agreement with numerical results (correlation coefficient = 0.995), and simulated lesion images yielded a significant (2.92 dB; p < 0.001) improvement in contrast-tonoise ratio when rendered using the 1.5-D ARFI array.
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