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Masud AA, Liu J. Ultrasonic surface acoustic wave elastography: A review of basic theories, technical developments, and medical applications. Med Phys 2024; 51:3220-3244. [PMID: 38597908 DOI: 10.1002/mp.17063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 02/19/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024] Open
Abstract
Physiological and pathological changes in tissues often cause changes in tissue mechanical properties, making tissue elastography an effective modality in medical imaging. Among the existing elastography methods, ultrasound elastography is of great interest due to the inherent advantages of ultrasound imaging technology, such as low cost, portability, safety, and wide availability. However, most current ultrasound elastography methods are based on the bulk shear wave; they can image deep tissues but cannot image superficial tissues. To address this challenge, ultrasonic elastography methods based on surface acoustic waves have been proposed. In this paper, we present a comprehensive review of ultrasound-based surface acoustic wave elastography techniques, including their theoretical foundations, technical implementations, and existing medical applications. The goal is to provide a concise summary of the state-of-the-art of this field, hoping to offer a reliable reference for the further development of these techniques and foster the expansion of their medical applications.
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Affiliation(s)
- Abdullah Al Masud
- Biomedical Acoustics Research Laboratory, Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA
| | - Jingfei Liu
- Biomedical Acoustics Research Laboratory, Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA
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Kerensky MJ, Paul A, Routkevitch D, Hersh AM, Kempski Leadingham KM, Davidar AD, Judy BF, Punnoose J, Williams A, Kumar A, Lehner K, Smith B, Son JK, Azadi JR, Shekhar H, Mercado-Shekhar KP, Thakor NV, Theodore N, Manbachi A. Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies. COMMUNICATIONS MEDICINE 2024; 4:4. [PMID: 38182729 PMCID: PMC10770351 DOI: 10.1038/s43856-023-00430-6] [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: 05/05/2023] [Accepted: 12/19/2023] [Indexed: 01/07/2024] Open
Abstract
BACKGROUND Tension in the spinal cord is a trademark of tethered cord syndrome. Unfortunately, existing tests cannot quantify tension across the bulk of the cord, making the diagnostic evaluation of stretch ambiguous. A potential non-destructive metric for spinal cord tension is ultrasound-derived shear wave velocity (SWV). The velocity is sensitive to tissue elasticity and boundary conditions including strain. We use the term Ultrasound Tensography to describe the acoustic evaluation of tension with SWV. METHODS Our solution Tethered cord Assessment with Ultrasound Tensography (TAUT) was utilized in three sub-studies: finite element simulations, a cadaveric benchtop validation, and a neurosurgical case series. The simulation computed SWV for given tensile forces. The cadaveric model with induced tension validated the SWV-tension relationship. Lastly, SWV was measured intraoperatively in patients diagnosed with tethered cords who underwent treatment (spinal column shortening). The surgery alleviates tension by decreasing the vertebral column length. RESULTS Here we observe a strong linear relationship between tension and squared SWV across the preclinical sub-studies. Higher tension induces faster shear waves in the simulation (R2 = 0.984) and cadaveric (R2 = 0.951) models. The SWV decreases in all neurosurgical procedures (p < 0.001). Moreover, TAUT has a c-statistic of 0.962 (0.92-1.00), detecting all tethered cords. CONCLUSIONS This study presents a physical, clinical metric of spinal cord tension. Strong agreement among computational, cadaveric, and clinical studies demonstrates the utility of ultrasound-induced SWV for quantitative intraoperative feedback. This technology is positioned to enhance tethered cord diagnosis, treatment, and postoperative monitoring as it differentiates stretched from healthy cords.
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Affiliation(s)
- Max J Kerensky
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Abhijit Paul
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat, India
| | - Denis Routkevitch
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Andrew M Hersh
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kelley M Kempski Leadingham
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - A Daniel Davidar
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Brendan F Judy
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Joshua Punnoose
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Autumn Williams
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Avisha Kumar
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Kurt Lehner
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Beth Smith
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jennifer K Son
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Javad R Azadi
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Himanshu Shekhar
- Discipline of Electrical Engineering, Indian Institute of Technology Gandhinagar, Gujarat, India
| | - Karla P Mercado-Shekhar
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat, India
| | - Nitish V Thakor
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nicholas Theodore
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Amir Manbachi
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- HEPIUS Innovation Laboratory, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA.
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Sebastian JA, Strohm EM, Baranger J, Villemain O, Kolios MC, Simmons CA. Assessing engineered tissues and biomaterials using ultrasound imaging: In vitro and in vivo applications. Biomaterials 2023; 296:122054. [PMID: 36842239 DOI: 10.1016/j.biomaterials.2023.122054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 01/24/2023] [Accepted: 02/11/2023] [Indexed: 02/18/2023]
Abstract
Quantitative assessment of the structural, functional, and mechanical properties of engineered tissues and biomaterials is fundamental to their development for regenerative medicine applications. Ultrasound (US) imaging is a non-invasive, non-destructive, and cost-effective technique capable of longitudinal and quantitative monitoring of tissue structure and function across centimeter to sub-micron length scales. Here we present the fundamentals of US to contextualize its application for the assessment of biomaterials and engineered tissues, both in vivo and in vitro. We review key studies that demonstrate the versatility and broad capabilities of US for clinical and pre-clinical biomaterials research. Finally, we highlight emerging techniques that further extend the applications of US, including for ultrafast imaging of biomaterials and engineered tissues in vivo and functional monitoring of stem cells, organoids, and organ-on-a-chip systems in vitro.
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Affiliation(s)
- Joseph A Sebastian
- Institute of Biomedical Engineering, University of Toronto, Toronto, Canada; Translational Biology and Engineering Program, Ted Rogers Center for Heart Research, Toronto, Canada.
| | - Eric M Strohm
- Translational Biology and Engineering Program, Ted Rogers Center for Heart Research, Toronto, Canada; Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada
| | - Jérôme Baranger
- Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Olivier Villemain
- Labatt Family Heart Centre, The Hospital for Sick Children, University of Toronto, Toronto, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Michael C Kolios
- Department of Physics, Toronto Metropolitan University, Toronto, Canada; Institute of Biomedical Engineering, Science and Technology (iBEST), A Partnership Between Toronto Metropolitan University and St. Michael's Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
| | - Craig A Simmons
- Institute of Biomedical Engineering, University of Toronto, Toronto, Canada; Translational Biology and Engineering Program, Ted Rogers Center for Heart Research, Toronto, Canada; Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada.
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Hobson EC, Li W, Juliar BA, Putnam AJ, Stegemann JP, Deng CX. Resonant acoustic rheometry for non-contact characterization of viscoelastic biomaterials. Biomaterials 2021; 269:120676. [PMID: 33485213 DOI: 10.1016/j.biomaterials.2021.120676] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 11/26/2022]
Abstract
Resonant Acoustic Rheometry (RAR) is a new, non-contact technique to characterize the mechanical properties of soft and viscoelastic biomaterials, such as hydrogels, that are used to mimic the extracellular matrix in tissue engineering. RAR uses a focused ultrasound pulse to generate a microscale perturbation at the sample surface and tracks the ensuing surface wave using pulse-echo ultrasound. The frequency spectrum of the resonant surface waves is analyzed to extract viscoelastic material properties. In this study, RAR was used to characterize fibrin, gelatin, and agarose hydrogels. Single time point measurements of gelled samples with static mechanical properties showed that RAR provided consistent quantitative data and measured intrinsic material characteristics independent of ultrasound parameters. RAR was also used to longitudinally track dynamic changes in viscoelastic properties over the course of fibrin gelation, revealing distinct phase and material property transitions. Application of RAR was verified using finite element modeling and the results were validated against rotational shear rheometry. Importantly, RAR circumvents some limitations of conventional rheology methods and can be performed in a high-throughput manner using conventional labware. Overall, these studies demonstrate that RAR can be a valuable tool to noninvasively quantify the viscoelastic mechanical properties of soft hydrogel biomaterials.
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Affiliation(s)
- Eric C Hobson
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48105, USA
| | - Weiping Li
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48105, USA
| | - Benjamin A Juliar
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48105, USA
| | - Andrew J Putnam
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48105, USA
| | - Jan P Stegemann
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48105, USA.
| | - Cheri X Deng
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48105, USA.
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Osapoetra LO, Watson DM, McAleavey SA. Intraocular Pressure-dependent Corneal Elasticity Measurement Using High-frequency Ultrasound. ULTRASONIC IMAGING 2019; 41:251-270. [PMID: 31271117 DOI: 10.1177/0161734619858386] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Measurement of corneal biomechanical properties can aid in predicting corneal responses to diseases and surgeries. For delineation of spatially resolved distribution of corneal elasticity, high-resolution elastography system is required. In this study, we demonstrate a high-resolution elastography system using high-frequency ultrasound for ex-vivo measurement of intraocular pressure (IOP)-dependent corneal wave speed. Tone bursts of 500 Hz vibrations were generated on the corneal surface using an electromagnetic shaker. A 35-MHz single-element transducer was used to track the resulting anti-symmetrical Lamb wave in the cornea. We acquired spatially resolved wave speed images of the cornea at IOPs of 7, 11, 15, 18, 22, and 29 mmHg. The IOP dependence of corneal wave speed is apparent from these images. Statistical analysis of measured wave speed as a function of IOP revealed a linear relation between wave speed and IOP cs = 0.37 + 0.22 × IOP, with the coefficient of determination R2 = 0.86. We also observed depth-dependent variations of wave speed in the cornea, decreasing from anterior toward posterior. This depth dependence is more pronounced at higher IOP values. This study demonstrates the potential of high-frequency ultrasound elastography in the characterization of spatially resolved corneal biomechanical properties.
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Affiliation(s)
| | - Dan M Watson
- 1 Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA
| | - Stephen A McAleavey
- 2 Department of Biomedical Engineering, University of Rochester, Rochester, NY, USA
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Mercado-Shekhar KP, Kleven RT, Aponte Rivera H, Lewis R, Karani KB, Vos HJ, Abruzzo TA, Haworth KJ, Holland CK. Effect of Clot Stiffness on Recombinant Tissue Plasminogen Activator Lytic Susceptibility in Vitro. ULTRASOUND IN MEDICINE & BIOLOGY 2018; 44:2710-2727. [PMID: 30268531 PMCID: PMC6551517 DOI: 10.1016/j.ultrasmedbio.2018.08.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 08/01/2018] [Accepted: 08/10/2018] [Indexed: 05/05/2023]
Abstract
The lytic recombinant tissue plasminogen activator (rt-PA) is the only drug approved by the Food and Drug Administration for treating ischemic stroke. Less than 40% of patients with large vessel occlusions who are treated with rt-PA have improved blood flow. However, up to 6% of all patients receiving rt-PA develop intracerebral hemorrhage. Predicting the efficacy of rt-PA treatment a priori could help guide therapeutic decision making, such that rt-PA is administered only to those individuals who would benefit from this treatment. Clot composition and structure affect the lytic efficacy of rt-PA and have an impact on elasticity. However, the relationship between clot elasticity and rt-PA lytic susceptibility has not been adequately investigated. The goal of this study was to quantify the relationship between clot elasticity and rt-PA susceptibility in vitro. Human and porcine highly retracted and mildly retracted clots were fabricated in glass pipettes. The rt-PA lytic susceptibility was evaluated in vitro using the percent clot mass loss. The Young's moduli of the clots were estimated using ultrasound-based single-track-location shear wave elasticity imaging. The percent mass loss in mildly retracted porcine and human clots (28.9 ± 6.1% and 45.2 ± 7.1%, respectively) was significantly higher (p < 0.05) than in highly retracted porcine and human clots (10.9 ± 2.1% and 25.5 ± 10.0%, respectively). Furthermore, the Young's moduli of highly retracted porcine and human clots (5.33 ± 0.92 and 3.21 ± 1.97 kPa, respectively) were significantly higher (p < 0.05) than those of mildly retracted porcine and human clots (2.66 ± 0.55 and 0.79 ± 0.21 kPa, respectively). The results revealed an inverse relationship between the percent clot mass loss and Young's modulus. These findings motivate continued investigation of ultrasound-based methods to assess clot stiffness in order to predict rt-PA thrombolytic efficacy.
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Affiliation(s)
- Karla P Mercado-Shekhar
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
| | - Robert T Kleven
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA
| | - Hermes Aponte Rivera
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Ryden Lewis
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Kunal B Karani
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Hendrik J Vos
- Department of Biomedical Engineering, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Todd A Abruzzo
- Department of Radiology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Kevin J Haworth
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA; Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA
| | - Christy K Holland
- Division of Cardiovascular Health and Disease, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio, USA; Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA
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Parker KJ, Ormachea J, Hah Z. Group versus Phase Velocity of Shear Waves in Soft Tissues. ULTRASONIC IMAGING 2018; 40:343-356. [PMID: 30182816 DOI: 10.1177/0161734618796217] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Across the varieties of waves that have been studied in physics, it is well established that group velocities can be significantly greater than or less than phase velocities measured within comparable frequency bands, depending on the particular mechanisms involved. The distinction between group and phase velocities is important in elastography, because diagnoses are made based on shear wave speed estimations from a variety of techniques. We review the general definitions of group and phase velocity and examine their specific relations within an important general class of rheological models. For the class of tissues and materials exhibiting power law dispersion, group velocity is significantly greater than phase velocity, and simple expressions are shown to interrelate the commonly measured parameters. Examples are given from phantoms and tissues.
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Affiliation(s)
- Kevin J Parker
- 1 Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Juvenal Ormachea
- 1 Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
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In silico simulation of liver crack detection using ultrasonic shear wave imaging. BMC Med Imaging 2018; 18:15. [PMID: 29769030 PMCID: PMC5956542 DOI: 10.1186/s12880-018-0249-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 04/16/2018] [Indexed: 12/31/2022] Open
Abstract
Background Liver trauma is an important source of morbidity and mortality worldwide. A timely detection and precise evaluation of traumatic liver injury and the bleeding site is necessary. There is a need to develop better imaging modalities of hepatic injuries to increase the sensitivity of ultrasonic imaging techniques for sites of hemorrhage caused by cracks. In this study, we conduct an in silico simulation of liver crack detection and delineation using an ultrasonic shear wave imaging (USWI) based method. Methods We simulate the generation and propagation of the shear wave in a liver tissue medium having a crack using COMSOL. Ultrasound radio frequency (RF) signal synthesis and the two-dimensional speckle tracking algorithm are applied to simulate USWI in a medium with randomly distributed scatterers. Crack detection is performed using the directional filter and the edge detection algorithm rather than the conventional inversion algorithm. Cracks with varied sizes and locations are studied with our method and the crack localization results are compared with the given crack. Results Our pilot simulation study shows that, by using USWI combined with a directional filter cum edge detection technique, the near-end edge of the crack can be detected in all the three cracks that we studied. The detection errors are within 5%. For a crack of 1.6 mm thickness, little shear wave can pass through it and the far-end edge of the crack cannot be detected. The detected crack lengths using USWI are all slightly shorter than the actual crack length. The robustness of our method in detecting a straight crack, a curved crack and a subtle crack of 0.5 mm thickness is demonstrated. Conclusions In this paper, we simulate the use of a USWI based method for the detection and delineation of the crack in liver. The in silico simulation helps to improve understanding and interpretation of USWI measurements in a physical scattered liver medium with a crack. This pilot study provides a basis for improved insights in future crack detection studies in a tissue phantom or liver.
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Langdon JH, Elegbe E, Gonzalez RS, Osapoetra L, Ford T, McAleavey SA. Measurement of Liver Stiffness Using Shear Wave Elastography in a Rat Model: Factors Impacting Stiffness Measurement with Multiple- and Single-Tracking-Location Techniques. ULTRASOUND IN MEDICINE & BIOLOGY 2017; 43:2629-2639. [PMID: 28830643 PMCID: PMC5605410 DOI: 10.1016/j.ultrasmedbio.2017.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 07/02/2017] [Accepted: 07/07/2017] [Indexed: 05/08/2023]
Abstract
The clinical use of elastography for monitoring fibrosis progression is challenged by the subtle changes in liver stiffness associated with early-stage fibrosis and the comparatively large variance in stiffness estimates provided by elastography. Single-tracking-location (STL) shear wave elasticity imaging (SWEI) is an ultrasound elastography technique previously found to provide improved estimate precision compared with multiple-tracking-location (MTL) SWEI. Because of the improved precision, it is reasonable to expect that STL-SWEI would provide improved ability to differentiate liver fibrosis stage compared with MTL-SWEI. However, this expectation has not been previously challenged rigorously. In this work, the performance of STL- and MTL-SWEI in the setting of a rat model of liver fibrosis is characterized, and the advantages of STL-SWEI in staging fibrosis are explored. The purpose of this study was to determine what advantages, if any, arise from using STL-SWEI instead of MTL-SWEI in the characterization of fibrotic liver. Thus, the ability of STL-SWEI to differentiate livers at various METAVIR fibrosis scores, for ex vivo postmortem measurements, is explored. In addition, we examined the effect of the common confounding factor of fluid versus solid boundary conditions in SWEI experiments. Sprague-Dawley rats were treated with carbon tetrachloride over several weeks to produce liver disease of varying severity. STL and MTL stiffness measurements were performed ex vivo and compared with the METAVIR scores from histological analysis and the duration of treatment. A strong association was observed between liver stiffness and weeks of treatment with the liver toxin carbon tetrachloride. Direct comparison of STL- and MTL-SWEI measurements revealed no significant difference in ability to differentiate fibrosis stages based on SWEI mean values. However, image interquartile range was greatly improved in the case of STL-SWEI, compared with MTL-SWEI, at small beam spacing.
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Affiliation(s)
| | - Etana Elegbe
- University of Rochester, Rochester, New York, USA
| | | | | | - Tristan Ford
- University of Rochester, Rochester, New York, USA
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Effect of Ultrafast Imaging on Shear Wave Visualization and Characterization: An Experimental and Computational Study in a Pediatric Ventricular Model. APPLIED SCIENCES-BASEL 2017. [DOI: 10.3390/app7080840] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Saavedra AC, Zvietcovich F, Lavarello RJ, Castaneda B. Measurement of surface acoustic waves in high-frequency ultrasound: Preliminary results. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:3000-3003. [PMID: 29060529 DOI: 10.1109/embc.2017.8037488] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Skin lesions change elastic properties near the surface. In the last decades, several non-invasive elastography techniques have been developed for detecting the mechanical properties of tissue. In particular, harmonic elastography is characterized for inducing shear wave propagation by an external vibrator in order to estimate shear modulus. However, near the boundary region, propagation is governed by surface acoustic waves (SAW). This paper combines crawling waves elastography with a high-frequency ultrasound (HFUS) system for the estimation of the SAW-to-shear compensation factor when ultrasound (US) gel is used as coupling interface. Experiments explore the SAWspeed in a homogeneous phantom with a solid-water interface in order to corroborate theoretical findings. Subsequently, experiments in a solid-US gel interface are conducted in order to find the correct compensation factor. Preliminary results suggest that SAW propagation can be detected using HFUS, and shear velocity maps can be generated by applying the estimated empirical correction factor. This study will potentially avoid the underestimation of shear modulus when using SAW-based HFUS elastography which is promising for the better diagnosis of skin diseases.
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Sturm RM, Yerkes EB, Nicholas JL, Snow-Lisy D, Diaz Saldano D, Gandor PL, Halline CG, Rosoklija I, Rychlik K, Johnson EK, Cheng EY. Ultrasound Shear Wave Elastography: A Novel Method to Evaluate Bladder Pressure. J Urol 2017; 198:422-429. [PMID: 28366710 DOI: 10.1016/j.juro.2017.03.127] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2017] [Indexed: 12/25/2022]
Abstract
PURPOSE Children with bladder dysfunction resulting in increased storage pressure are at risk for renal deterioration. The current gold standard for evaluation of bladder pressure is urodynamics, an invasive test requiring catheterization. We evaluated ultrasound shear wave elastography as a novel means of assessing bladder biomechanical properties associated with increased bladder pressure. MATERIALS AND METHODS Concurrent shear wave elastography and urodynamics were performed. Ultrasound shear wave elastography images were obtained of the anterior and posterior wall when empty and at 25%, 50%, 75% and 100% expected bladder capacity, and end fill volume. Regions of interest were confirmed by a pediatric radiologist. Bladder cohorts were defined as compliant (capacity detrusor pressure less than 25 cm H2O) and noncompliant (25 cm H2O or greater). Pearson correlation coefficients and a mixed effects model evaluated the relationship between shear wave speed and detrusor pressure, compliance and normalized compliance. An unpaired t-test was used for between cohort analyses. RESULTS In all 23 subjects mean shear wave speed of the anterior and posterior bladder walls significantly correlated with detrusor pressure throughout filling. When comparing compliant and noncompliant bladders, mean shear wave speed and detrusor shear wave speed of the anterior wall significantly increased with filling of noncompliant bladders. Shear wave speed remained at baseline levels in compliant bladders. Mean shear wave speed of the anterior wall was significantly correlated with compliance and normalized compliance. CONCLUSIONS Ultrasound shear wave elastography bladder measurements correlate well with bladder storage pressure, and shear wave speed measurements differ between compliant and noncompliant bladders. This is the first known study to demonstrate that shear wave elastography is promising as a bedside modality for the assessment of bladder dysfunction in children.
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Affiliation(s)
- Renea M Sturm
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois.
| | - Elizabeth B Yerkes
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | - Jennifer L Nicholas
- Department of Radiology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | - Devon Snow-Lisy
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | - Dawn Diaz Saldano
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | - P Lacy Gandor
- Department of Radiology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | | | - Ilina Rosoklija
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | - Karen Rychlik
- Biostatistics Research Core, Stanley Manne Research Institute, Chicago, Illinois
| | - Emilie K Johnson
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
| | - Earl Y Cheng
- Division of Urology, Ann and Robert H. Lurie Children's Hospital, Chicago, Illinois
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McAleavey SA, Parker KJ, Ormachea J, Wood RW, Stodgell CJ, Katzman PJ, Pressman EK, Miller RK. Shear Wave Elastography in the Living, Perfused, Post-Delivery Placenta. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:1282-1288. [PMID: 27006269 DOI: 10.1016/j.ultrasmedbio.2016.01.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 06/05/2023]
Abstract
The placenta is the critical interface between the mother and the developing fetus and is essential for survival and growth. Despite the widespread use of ultrasound imaging and Doppler in obstetrics and gynecology and the recent growth of elastographic technologies, little is known about the biomechanical (elastic shear wave) properties of the placenta and the range of normal and pathologic parameters that are present. This study uses a well-developed protocol for perfusing whole placentas, post-delivery, to maintain tissue integrity and function for hours. In this model, the placenta is living, whole and maintained within normal physiologic parameters such as flow, arterial pressure and oxygen, throughout examination by ultrasound, Doppler and shear wave elastography. The preliminary results indicate that normal placental tissue on the fetal side has shear wave speeds on the order of 2 m/s, in a range similar to those of animal livers. Some abnormalities are found outside this range, and thus, elastographic measures of the placenta may provide useful assessments related to the state of the tissue.
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Affiliation(s)
- Stephen A McAleavey
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA
| | - Kevin J Parker
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA.
| | - Juvenal Ormachea
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA
| | - Ronald W Wood
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, New York, USA
| | - Christopher J Stodgell
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, New York, USA
| | - Philip J Katzman
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Eva K Pressman
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, New York, USA
| | - Richard K Miller
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, New York, USA
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Dalecki D, Mercado KP, Hocking DC. Quantitative Ultrasound for Nondestructive Characterization of Engineered Tissues and Biomaterials. Ann Biomed Eng 2015; 44:636-48. [PMID: 26581347 DOI: 10.1007/s10439-015-1515-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/13/2015] [Indexed: 12/15/2022]
Abstract
Non-invasive, non-destructive technologies for imaging and quantitatively monitoring the development of artificial tissues are critical for the advancement of tissue engineering. Current standard techniques for evaluating engineered tissues, including histology, biochemical assays and mechanical testing, are destructive approaches. Ultrasound is emerging as a valuable tool for imaging and quantitatively monitoring the properties of engineered tissues and biomaterials longitudinally during fabrication and post-implantation. Ultrasound techniques are rapid, non-invasive, non-destructive and can be easily integrated into sterile environments necessary for tissue engineering. Furthermore, high-frequency quantitative ultrasound techniques can enable volumetric characterization of the structural, biological, and mechanical properties of engineered tissues during fabrication and post-implantation. This review provides an overview of ultrasound imaging, quantitative ultrasound techniques, and elastography, with representative examples of applications of these ultrasound-based techniques to the field of tissue engineering.
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Affiliation(s)
- Diane Dalecki
- Department of Biomedical Engineering, University of Rochester, 310 Goergen Hall, P.O. Box 270168, Rochester, NY, 14627, USA.
| | - Karla P Mercado
- Department of Internal Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH, 45267, USA
| | - Denise C Hocking
- Department of Pharmacology and Physiology, University of Rochester, 601 Elmwood Avenue, Box 711, Rochester, NY, 14642, USA
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