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González-Cruz RD, Wan Y, Burgess A, Calvao D, Renken W, Vecchio F, Franck C, Kesari H, Hoffman-Kim D. Cortical spheroids show strain-dependent cell viability loss and neurite disruption following sustained compression injury. PLoS One 2024; 19:e0295086. [PMID: 39159236 PMCID: PMC11332998 DOI: 10.1371/journal.pone.0295086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 07/15/2024] [Indexed: 08/21/2024] Open
Abstract
Sustained compressive injury (SCI) in the brain is observed in numerous injury and pathological scenarios, including tumors, ischemic stroke, and traumatic brain injury-related tissue swelling. Sustained compressive injury is characterized by tissue loading over time, and currently, there are few in vitro models suitable to study neural cell responses to strain-dependent sustained compressive injury. Here, we present an in vitro model of sustained compressive neural injury via centrifugation. Spheroids were made from neonatal rat cortical cells seeded at 4000 cells/spheroid and cultured for 14 days in vitro. A subset of spheroids was centrifuged at 104, 209, 313 or 419 rads/s for 2 minutes. Modeling the physical deformation of the spheroids via finite element analyses, we found that spheroids centrifuged at the aforementioned angular velocities experienced pressures of 10, 38, 84 and 149 kPa, respectively, and compressive (resp. tensile) strains of 10% (5%), 18% (9%), 27% (14%) and 35% (18%), respectively. Quantification of LIVE-DEAD assay and Hoechst 33342 nuclear staining showed that centrifuged spheroids subjected to pressures above 10 kPa exhibited significantly higher DNA damage than control spheroids at 2, 8, and 24 hours post-injury. Immunohistochemistry of β3-tubulin networks at 2, 8, and 24 hours post-centrifugation injury showed increasing degradation of microtubules over time with increasing strain. Our findings show that cellular injuries occur as a result of specific levels and timings of sustained tissue strains. This experimental SCI model provides a high throughput in vitro platform to examine cellular injury, to gain insights into brain injury that could be targeted with therapeutic strategies.
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Affiliation(s)
- Rafael D. González-Cruz
- Department of Neuroscience, Brown University, Providence, RI, United States of America
- Carney Institute for Brain Science, Brown University, Providence, RI, United States of America
- School of Engineering, Brown University, Providence, RI, United States of America
| | - Yang Wan
- School of Engineering, Brown University, Providence, RI, United States of America
| | - Amina Burgess
- Institute for Biology, Engineering, and Medicine, Brown University Providence, RI, United States of America
| | - Dominick Calvao
- Institute for Biology, Engineering, and Medicine, Brown University Providence, RI, United States of America
| | - William Renken
- Department of Neuroscience, Brown University, Providence, RI, United States of America
| | - Francesca Vecchio
- Institute for Biology, Engineering, and Medicine, Brown University Providence, RI, United States of America
| | - Christian Franck
- Center for Traumatic Brain Injury, University of Wisconsin-Madison, Madison, WI, United States of America
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Haneesh Kesari
- School of Engineering, Brown University, Providence, RI, United States of America
| | - Diane Hoffman-Kim
- Department of Neuroscience, Brown University, Providence, RI, United States of America
- Carney Institute for Brain Science, Brown University, Providence, RI, United States of America
- Institute for Biology, Engineering, and Medicine, Brown University Providence, RI, United States of America
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2
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Wan Y, González-Cruz RD, Hoffman-Kim D, Kesari H. A mechanics theory for the exploration of a high-throughput, sterile 3D in vitro traumatic brain injury model. Biomech Model Mechanobiol 2024; 23:1179-1196. [PMID: 38970736 DOI: 10.1007/s10237-024-01832-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 02/19/2024] [Indexed: 07/08/2024]
Abstract
Brain injuries resulting from mechanical trauma represent an ongoing global public health issue. Several in vitro and in vivo models for traumatic brain injury (TBI) continue to be developed for delineating the various complex pathophysiological processes involved in its onset and progression. Developing an in vitro TBI model that is based on cortical spheroids is especially of great interest currently because they can replicate key aspects of in vivo brain tissue, including its electrophysiology, physicochemical microenvironment, and extracellular matrix composition. Being able to mechanically deform the spheroids are a key requirement in any effective in vitro TBI model. The spheroids' shape and size, however, make mechanically loading them, especially in a high-throughput, sterile, and reproducible manner, quite challenging. To address this challenge, we present an idea for a spheroid-based, in vitro TBI model in which the spheroids are mechanically loaded by being spun by a centrifuge. (An experimental demonstration of this new idea will be published shortly elsewhere.) An issue that can limit its utility and scope is that imaging techniques used in 2D and 3D in vitro TBI models cannot be readily applied in it to determine spheroid strains. In order to address this issue, we developed a continuum mechanics-based theory to estimate the spheroids' strains when they are being spun at a constant angular velocity. The mechanics theory, while applicable here to a special case of the centrifuge-based TBI model, is also of general value since it can help with the further exploration and development of TBI models.
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Affiliation(s)
- Yang Wan
- School of Engineering, Brown University, Providence, RI, 02912, USA
| | - Rafael D González-Cruz
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
- Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI, 02906, USA
| | - Diane Hoffman-Kim
- Department of Neuroscience, Brown University, Providence, RI, 02912, USA
- Robert J. and Nancy D. Carney Institute for Brain Science, Brown University, Providence, RI, 02906, USA
- Center for Biomedical Engineering, Brown University, Providence, RI, 02912, USA
| | - Haneesh Kesari
- School of Engineering, Brown University, Providence, RI, 02912, USA.
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3
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Esterov D, Yin Z, Persaud T, Shan X, Murphy MC, Ehman RL, Huston J, Brown AW. Association Between Anatomic and Clinical Indicators of Injury Severity After Moderate-Severe Traumatic Brain Injury: A Pilot Study Using Multiparametric Magnetic Resonance Imaging. Neurotrauma Rep 2024; 5:232-242. [PMID: 38524727 PMCID: PMC10960168 DOI: 10.1089/neur.2023.0122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024] Open
Abstract
This study sought to identify whether an anatomical indicator of injury severity as measured by multiparametric magnetic resonance imaging (MRI) including magnetic resonance elastography (MRE), is predictive of a clinical measure of injury severity after moderate-severe traumatic brain injury (TBI). Nine individuals who were admitted to acute inpatient rehabilitation after moderate-to-severe TBI completed a comprehensive MRI protocol prior to discharge from rehabilitation, which included conventional MRI with diffusion tensor imaging (DTI). Of those, five of nine also underwent brain MRE to measure the brain parenchyma stiffness. Clinical severity of injury was measured by the length of post-traumatic amnesia (PTA). MRI-assessed non-hemorrhage contusion score and hemorrhage score, DTI-measured white matter fractional anisotropy, and MRE-measured lesion stiffness were all assessed. A higher hemorrhagic score was significantly associated with a longer length of PTA (p = 0.026). Participants with a longer PTA tended to have a higher non-hemorrhage contusion score and softer contusion lesions than the contralateral control side, although the small sample size did not allow for assessment of a significant association. To our knowledge, this is the first report applying MRI/MRE imaging protocol to quantitate altered brain anatomy after moderate-severe TBI and its association with PTA, a known clinical predictor of post-acute outcome. Future larger studies could lead to the development of prediction models that integrate clinical data with anatomical (MRI), structural (DTI), and mechanical (MRE) changes caused by TBI, to inform prognosis and care planning.
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Affiliation(s)
- Dmitry Esterov
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Ziying Yin
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Trevor Persaud
- Department of Mayo Clinic School of Graduate Medical Education, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Xiang Shan
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Mathew C. Murphy
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Richard L. Ehman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - John Huston
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Allen W. Brown
- Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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4
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Gholampour S. Why Intracranial Compliance Is Not Utilized as a Common Practical Tool in Clinical Practice. Biomedicines 2023; 11:3083. [PMID: 38002083 PMCID: PMC10669292 DOI: 10.3390/biomedicines11113083] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
Intracranial compliance (ICC) holds significant potential in neuromonitoring, serving as a diagnostic tool and contributing to the evaluation of treatment outcomes. Despite its comprehensive concept, which allows consideration of changes in both volume and intracranial pressure (ICP), ICC monitoring has not yet established itself as a standard component of medical care, unlike ICP monitoring. This review highlighted that the first challenge is the assessment of ICC values, because of the invasive nature of direct measurement, the time-consuming aspect of non-invasive calculation through computer simulations, and the inability to quantify ICC values in estimation methods. Addressing these challenges is crucial, and the development of a rapid, non-invasive computer simulation method could alleviate obstacles in quantifying ICC. Additionally, this review indicated the second challenge in the clinical application of ICC, which involves the dynamic and time-dependent nature of ICC. This was considered by introducing the concept of time elapsed (TE) in measuring the changes in volume or ICP in the ICC equation (volume change/ICP change). The choice of TE, whether short or long, directly influences the ICC values that must be considered in the clinical application of the ICC. Compensatory responses of the brain exhibit non-monotonic and variable changes in long TE assessments for certain disorders, contrasting with the mono-exponential pattern observed in short TE assessments. Furthermore, the recovery behavior of the brain undergoes changes during the treatment process of various brain disorders when exposed to short and long TE conditions. The review also highlighted differences in ICC values across brain disorders with various strain rates and loading durations on the brain, further emphasizing the dynamic nature of ICC for clinical application. The insight provided in this review may prove valuable to professionals in neurocritical care, neurology, and neurosurgery for standardizing ICC monitoring in practical application related to the diagnosis and evaluation of treatment outcomes in brain disorders.
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Affiliation(s)
- Seifollah Gholampour
- Department of Neurological Surgery, University of Chicago, Chicago, IL 60637, USA
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5
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Lee GY, Kim OH, Kim ER, Lee HJ. Biomechanical forces in the aged brain: Relationship to AD. Life Sci 2022; 312:121237. [PMID: 36436618 DOI: 10.1016/j.lfs.2022.121237] [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: 09/07/2022] [Revised: 11/17/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022]
Abstract
The pathogenesis of neurodegenerative disorders, including Alzheimer's disease, has been studied with a focus on biochemical mechanisms, such as the amyloid-β plaque deposition and removal. Recently, the importance of brain microenvironmental cues, which comprise the sophisticated cellular and fluid system, has been emphasized in the aged brain or in pathological conditions. Especially, substrate rigidity and biomechanical forces of the brain microenvironment determine the function of glial cells and neurons; furthermore, these microenvironmental cues change with age. However, our understanding of role of the biomechanical cues on glial cells and neurons is relatively poor. In this review, we briefly introduce an overview of biomechanical forces that present in the aged brain and its sensations, and then examine the brain in Alzheimer's disease, which constitutes a representative neurodegenerative disorder, with regard to changes in the biomechanical forces associated with disease and aging.
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Affiliation(s)
- Gyeong Yun Lee
- Department of Anatomy and Cell Biology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Ok-Hyeon Kim
- Department of Anatomy and Cell Biology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Eun Ran Kim
- Division of Endocrine and Kidney Research, Department of Chronic Disease Convergence Research, Korea National Institute of Health, Korea Disease Control and Prevention Agency, Cheongju, Republic of Korea.
| | - Hyun Jung Lee
- Department of Anatomy and Cell Biology, College of Medicine, Chung-Ang University, Seoul, Republic of Korea; Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul, Republic of Korea.
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6
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Shao X, Liu Z, Mao S, Han L. Unraveling the Mechanobiology Underlying Traumatic Brain Injury with Advanced Technologies and Biomaterials. Adv Healthc Mater 2022; 11:e2200760. [PMID: 35841392 DOI: 10.1002/adhm.202200760] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/27/2022] [Indexed: 01/27/2023]
Abstract
Traumatic brain injury (TBI) is a worldwide health and socioeconomic problem, associated with prolonged and complex neurological aftermaths, including a variety of functional deficits and neurodegenerative disorders. Research on the long-term effects has highlighted that TBI shall be regarded as a chronic health condition. The initiation and exacerbation of TBI involve a series of mechanical stimulations and perturbations, accompanied by mechanotransduction events within the brain tissues. Mechanobiology thus offers a unique perspective and likely promising approach to unravel the underlying molecular and biochemical mechanisms leading to neural cells dysfunction after TBI, which may contribute to the discovery of novel targets for future clinical treatment. This article investigates TBI and the subsequent brain dysfunction from a lens of neuromechanobiology. Following an introduction, the mechanobiological insights are examined into the molecular pathology of TBI, and then an overview is given of the latest research technologies to explore neuromechanobiology, with particular focus on microfluidics and biomaterials. Challenges and prospects in the current field are also discussed. Through this article, it is hoped that extensive technical innovation in biomedical devices and materials can be encouraged to advance the field of neuromechanobiology, paving potential ways for the research and rehabilitation of neurotrauma and neurological diseases.
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Affiliation(s)
- Xiaowei Shao
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China.,Suzhou Research Institute, Shandong University, Suzhou, Jiangsu, 215123, China
| | - Zhongqian Liu
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China
| | - Shijie Mao
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China
| | - Lin Han
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China
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7
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Hu L, Yang S, Jin B, Wang C. Advanced Neuroimaging Role in Traumatic Brain Injury: A Narrative Review. Front Neurosci 2022; 16:872609. [PMID: 35495065 PMCID: PMC9043279 DOI: 10.3389/fnins.2022.872609] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/14/2022] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is a common source of morbidity and mortality among civilians and military personnel. Initial routine neuroimaging plays an essential role in rapidly assessing intracranial injury that may require intervention. However, in the context of TBI, limitations of routine neuroimaging include poor visualization of more subtle changes of brain parenchymal after injury, poor prognostic ability and inability to analyze cerebral perfusion, metabolite and mechanical properties. With the development of modern neuroimaging techniques, advanced neuroimaging techniques have greatly boosted the studies in the diagnosis, prognostication, and eventually impacting treatment of TBI. Advances in neuroimaging techniques have shown potential, including (1) Ultrasound (US) based techniques (contrast-enhanced US, intravascular US, and US elastography), (2) Magnetic resonance imaging (MRI) based techniques (diffusion tensor imaging, magnetic resonance spectroscopy, perfusion weighted imaging, magnetic resonance elastography and functional MRI), and (3) molecular imaging based techniques (positron emission tomography and single photon emission computed tomography). Therefore, in this review, we aim to summarize the role of these advanced neuroimaging techniques in the evaluation and management of TBI. This review is the first to combine the role of the US, MRI and molecular imaging based techniques in TBI. Advanced neuroimaging techniques have great potential; still, there is much to improve. With more clinical validation and larger studies, these techniques will be likely applied for routine clinical use from the initial research.
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Affiliation(s)
- Ling Hu
- Department of Ultrasound, Hangzhou Women’s Hospital, Hangzhou, China
| | - Siyu Yang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Bo Jin
- Department of Neurology, Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Hangzhou, China
| | - Chao Wang
- Department of Radiology, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
- *Correspondence: Chao Wang,
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8
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Ngo MT, Harley BAC. Progress in mimicking brain microenvironments to understand and treat neurological disorders. APL Bioeng 2021; 5:020902. [PMID: 33869984 PMCID: PMC8034983 DOI: 10.1063/5.0043338] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/22/2021] [Indexed: 12/16/2022] Open
Abstract
Neurological disorders including traumatic brain injury, stroke, primary and metastatic brain tumors, and neurodegenerative diseases affect millions of people worldwide. Disease progression is accompanied by changes in the brain microenvironment, but how these shifts in biochemical, biophysical, and cellular properties contribute to repair outcomes or continued degeneration is largely unknown. Tissue engineering approaches can be used to develop in vitro models to understand how the brain microenvironment contributes to pathophysiological processes linked to neurological disorders and may also offer constructs that promote healing and regeneration in vivo. In this Perspective, we summarize features of the brain microenvironment in normal and pathophysiological states and highlight strategies to mimic this environment to model disease, investigate neural stem cell biology, and promote regenerative healing. We discuss current limitations and resulting opportunities to develop tissue engineering tools that more faithfully recapitulate the aspects of the brain microenvironment for both in vitro and in vivo applications.
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Affiliation(s)
- Mai T. Ngo
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Brendan A. C. Harley
- Author to whom correspondence should be addressed:. Tel.: (217) 244-7112. Fax: (217) 333-5052
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9
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Eskandari F, Shafieian M, Aghdam MM, Laksari K. Mind the gap: A mechanobiological hypothesis for the role of gap junctions in the mechanical properties of injured brain tissue. J Mech Behav Biomed Mater 2020; 115:104240. [PMID: 33310267 DOI: 10.1016/j.jmbbm.2020.104240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 11/14/2020] [Accepted: 11/27/2020] [Indexed: 10/22/2022]
Abstract
Despite more than half a century of work on the brain biomechanics, there are still significant unknowns about this tissue. Since the brain is highly susceptible to injury, damage biomechanics has been one of the main areas of interest to the researchers in the field of brain biomechanics. In many previous studies, mechanical properties of brain tissue under sub-injury and injury level loading conditions have been addressed; however, to the best of our knowledge, the role of cell-cell interactions in the mechanical behavior of brain tissue has not been well examined yet. This note introduces the hypothesis that gap junctions as the major type of cell-cell junctions in the brain tissue play a pivotal role in the mechanical properties of the tissue and their failure during injury leads to changes in brain's material properties. According to this hypothesis, during an injury, the gap junctions are damaged, leading to a decrease in tissue stiffness, whereas following the injury, new junction proteins are expressed, leading to an increase in tissue stiffness. We suggest that considering the mechanobiological effect of gap junctions in the material properties of brain tissue may help better understand the brain injury mechanism.
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Affiliation(s)
- Faezeh Eskandari
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mehdi Shafieian
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Mohammad M Aghdam
- Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Kaveh Laksari
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA
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10
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Mijailovic AS, Galarza S, Raayai-Ardakani S, Birch NP, Schiffman JD, Crosby AJ, Cohen T, Peyton SR, Van Vliet KJ. Localized characterization of brain tissue mechanical properties by needle induced cavitation rheology and volume controlled cavity expansion. J Mech Behav Biomed Mater 2020; 114:104168. [PMID: 33218928 DOI: 10.1016/j.jmbbm.2020.104168] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 08/10/2020] [Accepted: 10/23/2020] [Indexed: 11/30/2022]
Abstract
Changes in the elastic properties of brain tissue have been correlated with injury, cancers, and neurodegenerative diseases. However, discrepancies in the reported elastic moduli of brain tissue are persistent, and spatial inhomogeneities complicate the interpretation of macroscale measurements such as rheology. Here we introduce needle induced cavitation rheology (NICR) and volume-controlled cavity expansion (VCCE) as facile methods to measure the apparent Young's modulus E of minimally manipulated brain tissue, at specific tissue locations and with sub-millimeter spatial resolution. For different porcine brain regions and sections analyzed by NICR, we found E to be 3.7 ± 0.7 kPa and 4.8 ± 1.0 kPa for gray matter, and white matter, respectively. For different porcine brain regions and sections analyzed by VCCE, we found E was 0.76 ± 0.02 kPa for gray matter and 0.92 ± 0.01 kPa for white matter. Measurements from VCCE were more similar to those obtained from macroscale shear rheology (0.75 ± 0.06 kPa) and from instrumented microindentation of white matter (0.97 ± 0.40 kPa) and gray matter (0.86 ± 0.20 kPa). We attributed the higher stiffness reported from NICR to that method's assumption of a cavitation instability due to a neo-Hookean constitutive response, which does not capture the strain-stiffening behavior of brain tissue under large strains, and therefore did not provide appropriate measurements. We demonstrate via both analytical modeling of a spherical cavity and finite element modeling of a needle geometry, that this strain stiffening may prevent a cavitation instability. VCCE measurements take this stiffening behavior into account by employing an incompressible one-term Ogden model to find the nonlinear elastic properties of the tissue. Overall, VCCE afforded rapid and facile measurement of nonlinear mechanical properties of intact, healthy mammalian brain tissue, enabling quantitative comparison among brain tissue regions and also between species. Finally, accurate estimation of elastic properties for this strain stiffening tissue requires methods that include appropriate constitutive models of the brain tissue response, which here are represented by inclusion of the Ogden model in VCCE.
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Affiliation(s)
- Aleksandar S Mijailovic
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Sualyneth Galarza
- Department of Chemical Engineering, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Shabnam Raayai-Ardakani
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Nathan P Birch
- Department of Chemical Engineering, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Jessica D Schiffman
- Department of Chemical Engineering, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Alfred J Crosby
- Department of Polymer Science and Engineering, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Tal Cohen
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Shelly R Peyton
- Department of Chemical Engineering, University of Massachusetts-Amherst, Amherst, MA, 01003, USA.
| | - Krystyn J Van Vliet
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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11
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Kirby MA, Zhou K, Pitre JJ, Gao L, Li D, Pelivanov I, Song S, Li C, Huang Z, Shen T, Wang R, O’Donnell M. Spatial resolution in dynamic optical coherence elastography. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-16. [PMID: 31535538 PMCID: PMC6749618 DOI: 10.1117/1.jbo.24.9.096006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Accepted: 08/26/2019] [Indexed: 05/03/2023]
Abstract
Dynamic optical coherence elastography (OCE) tracks elastic wave propagation speed within tissue, enabling quantitative three-dimensional imaging of the elastic modulus. We show that propagating mechanical waves are mode converted at interfaces, creating a finite region on the order of an acoustic wavelength where there is not a simple one-to-one correspondence between wave speed and elastic modulus. Depending on the details of a boundary’s geometry and elasticity contrast, highly complex propagating fields produced near the boundary can substantially affect both the spatial resolution and contrast of the elasticity image. We demonstrate boundary effects on Rayleigh waves incident on a vertical boundary between media of different shear moduli. Lateral resolution is defined by the width of the transition zone between two media and is the limit at which a physical inclusion can be detected with full contrast. We experimentally demonstrate results using a spectral-domain OCT system on tissue-mimicking phantoms, which are replicated using numerical simulations. It is shown that the spatial resolution in dynamic OCE is determined by the temporal and spatial characteristics (i.e., bandwidth and spatial pulse width) of the propagating mechanical wave. Thus, mechanical resolution in dynamic OCE inherently differs from the optical resolution of the OCT imaging system.
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Affiliation(s)
- Mitchell A. Kirby
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Kanheng Zhou
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Dundee, School of Science and Engineering, Dundee, United Kingdom
| | - John J. Pitre
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Liang Gao
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - David Li
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Chemical Engineering, Seattle, Washington, United States
| | - Ivan Pelivanov
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- Address all correspondence to Ivan Pelivanov, E-mail:
| | - Shaozhen Song
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
| | - Chunhui Li
- University of Dundee, School of Science and Engineering, Dundee, United Kingdom
| | - Zhihong Huang
- University of Dundee, School of Science and Engineering, Dundee, United Kingdom
| | - Tueng Shen
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
| | - Ruikang Wang
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
- University of Washington, Department of Ophthalmology, Seattle, Washington, United States
| | - Matthew O’Donnell
- University of Washington, Department of Bioengineering, Seattle, Washington, United States
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12
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Yeung J, Jugé L, Hatt A, Bilston LE. Paediatric brain tissue properties measured with magnetic resonance elastography. Biomech Model Mechanobiol 2019; 18:1497-1505. [PMID: 31055692 DOI: 10.1007/s10237-019-01157-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/23/2019] [Indexed: 12/25/2022]
Abstract
The aim of this study is to characterise the stiffness of white and grey matter in paediatric subjects using magnetic resonance elastography (MRE) and to determine whether these properties change throughout normal development. MRE was performed using a clinical 3T MRI scanner at three frequencies (30, 40 and 60 Hz) on 36 healthy paediatric subjects aged between 7 and 18 years (19 F) and 11 adults aged 23-44 years (6 F). Anatomical and diffusion tensor imaging was also collected. The stiffness quantified as the magnitude of the complex shear modulus (G*), fractional anisotropy (FA), mean diffusivity (MD) and volume of white and grey matter were calculated. One-way analysis of variance and Tukey's multiple comparison tests were used to compare data in age groups separated into children (7-12 years), adolescents (13-18 years) and adults (18+ years), and Spearman's correlations were performed for paediatric data. White and grey matter stiffness for each frequency and their frequency dependence was found to be very similar in paediatric and adult subjects (p > 0.05 all variables). No significant correlations were found when comparing G* with age, FA, MD or volume. Adult G*, FA, MD and volume values were within range of others reported in the literature. Paediatric white and grey matter stiffness values are similar to those of adults. We conclude that clinically, adult values can be used as a baseline measure in paediatric brain MRE.
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Affiliation(s)
- Jade Yeung
- Neuroscience Research Australia, Margarete Ainsworth Building, Barker Street, Randwick, NSW, 2031, Australia
| | - Lauriane Jugé
- Neuroscience Research Australia, Margarete Ainsworth Building, Barker Street, Randwick, NSW, 2031, Australia.,University of New South Wales, Sydney, NSW, 2031, Australia
| | - Alice Hatt
- Neuroscience Research Australia, Margarete Ainsworth Building, Barker Street, Randwick, NSW, 2031, Australia
| | - Lynne E Bilston
- Neuroscience Research Australia, Margarete Ainsworth Building, Barker Street, Randwick, NSW, 2031, Australia. .,University of New South Wales, Sydney, NSW, 2031, Australia.
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Lay FY, Chen PY, Cheng HF, Kuo YM, Huang CC. Ex Vivo Evaluation of Mouse Brain Elasticity Using High-Frequency Ultrasound Elastography. IEEE Trans Biomed Eng 2019; 66:3426-3435. [PMID: 30892196 DOI: 10.1109/tbme.2019.2905551] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
OBJECTIVE Most neurodegenerative diseases are highly linked with aging. The mechanical properties of the brain should be determined for predicting and diagnosing age-related brain diseases. A preclinical animal study is crucial for neurological disease research. However, estimation of the elasticity properties of different regions of mouse brains remains difficult because of the size of the brain. In this paper, high-frequency ultrasound elastography (HFUSE) based on shear wave imaging was proposed for mapping the stiffness of the mouse brain at different ages ex vivo. METHODS For HFUSE, a 40-MHz ultrasound array transducer with an ultrafast ultrasound imaging system was used in this paper. The accuracy and resolution during HFUSE were determined through a mechanical testing system and by conducting phantom experiments. RESULTS In the experiments, the error in the elastic modulus measurement was approximately 10% on average, and the axial resolution was 248 μm. Animal testing was conducted using mice that were 4 (young aged) and 11 (middle aged) months old. The elasticity distributions of the cortex and hippocampus in the mouse brains were obtained through HFUSE. CONCLUSION The average shear moduli of the cortex and hippocampus were 3.84 and 2.33 kPa for the 4-month-old mice and 3.77 and 1.94 kPa for the 11-month-old mice, respectively. No statistical difference was observed in the cortex stiffness of mice of different ages. However, the hippocampus significantly softened with aging.
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Zeiler FA, Kim DJ, Cabeleira M, Calviello L, Smielewski P, Czosnyka M. Impaired cerebral compensatory reserve is associated with admission imaging characteristics of diffuse insult in traumatic brain injury. Acta Neurochir (Wien) 2018; 160:2277-2287. [PMID: 30251196 PMCID: PMC6267721 DOI: 10.1007/s00701-018-3681-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 09/17/2018] [Indexed: 12/14/2022]
Abstract
Background Continuous assessment of cerebral compensatory reserve is possible using the moving correlation between pulse amplitude of intra-cranial pressure (AMP) and intra-cranial pressure (ICP), called RAP. Little is known about the behavior and associations of this index in adult traumatic brain injury (TBI). The goal of this study is to evaluate the association between admission cerebral imaging findings and RAP over the course of the acute intensive care unit stay. Methods We retrospectively reviewed 358 adult TBI patients admitted to the Addenbrooke’s Hospital, University of Cambridge, from March 2005 to December 2016. Only non-craniectomy patients were studied. Using archived high frequency physiologic signals, RAP was derived and analyzed over the first 48 h and first 10 days of recording in each patient, using grand mean, percentage of time above various thresholds, and integrated area under the curve (AUC) of RAP over time. Associations between these values and admission computed tomography (CT) injury characteristics were evaluated. Results The integrated AUC, based on various thresholds of RAP, was statistically associated with admission CT markers of diffuse TBI and cerebral edema. Admission CT findings of cortical gyral effacement, lateral ventricle compression, diffuse cortical subarachnoid hemorrhage (SAH), thickness of cortical SAH, presence of bilateral contusions, and subcortical diffuse axonal injury (DAI) were all associated with AUC of RAP over time. Joncheere-Terpstra testing indicated a statistically significant increase in mean RAP AUC across ordinal categories of the abovementioned associated CT findings. Conclusions RAP is associated with cerebral CT injury patterns of diffuse injury and edema, providing some confirmation of its potential measurement of cerebral compensatory reserve in TBI. Electronic supplementary material The online version of this article (10.1007/s00701-018-3681-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Frederick A. Zeiler
- Division of Anaesthesia, Addenbrooke’s Hospital, University of Cambridge, Cambridge, UK
- Section of Surgery, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB Canada
- Clinician Investigator Program, Rady Faculty of Health Science, University of Manitoba, Winnipeg, Canada
| | - Dong-Joo Kim
- Department of Brain and Cognitive Engineering, Korea University, Seoul, South Korea
| | - Manuel Cabeleira
- Section of Brain Physics, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
| | - Leanne Calviello
- Section of Brain Physics, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
| | - Peter Smielewski
- Section of Brain Physics, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
| | - Marek Czosnyka
- Section of Brain Physics, Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
- Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
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15
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Bigot M, Chauveau F, Beuf O, Lambert SA. Magnetic Resonance Elastography of Rodent Brain. Front Neurol 2018; 9:1010. [PMID: 30538670 PMCID: PMC6277573 DOI: 10.3389/fneur.2018.01010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 11/08/2018] [Indexed: 12/28/2022] Open
Abstract
Magnetic resonance elastography (MRE) is a non-invasive imaging technique, using the propagation of mechanical waves as a probe to palpate biological tissues. It consists in three main steps: production of shear waves within the tissue; encoding subsequent tissue displacement in magnetic resonance images; and extraction of mechanical parameters based on dedicated reconstruction methods. These three steps require an acoustic-frequency mechanical actuator, magnetic resonance imaging acquisition, and a post-processing tool for which no turnkey technology is available. The aim of the present review is to outline the state of the art of reported set-ups to investigate rodent brain mechanical properties. The impact of experimental conditions in dimensioning the set-up (wavelength and amplitude of the propagated wave, spatial resolution, and signal-to-noise ratio of the acquisition) on the accuracy and precision of the extracted parameters is discussed, as well as the influence of different imaging sequences, scanners, electromagnetic coils, and reconstruction algorithms. Finally, the performance of MRE in demonstrating viscoelastic differences between structures constituting the physiological rodent brain, and the changes in brain parameters under pathological conditions, are summarized. The recently established link between biomechanical properties of the brain as obtained on MRE and structural factors assessed by histology is also studied. This review intends to give an accessible outline on how to conduct an elastography experiment, and on the potential of the technique in providing valuable information for neuroscientists.
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Affiliation(s)
- Mathilde Bigot
- Univ. Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - Fabien Chauveau
- Univ. Lyon, Lyon Neuroscience Research Center, CNRS UMR 5292, INSERM U1028, Univ. Lyon 1, Lyon, France
| | - Olivier Beuf
- Univ. Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - Simon A Lambert
- Univ. Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
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16
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Yin Z, Romano AJ, Manduca A, Ehman RL, Huston J. Stiffness and Beyond: What MR Elastography Can Tell Us About Brain Structure and Function Under Physiologic and Pathologic Conditions. Top Magn Reson Imaging 2018; 27:305-318. [PMID: 30289827 PMCID: PMC6176744 DOI: 10.1097/rmr.0000000000000178] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Brain magnetic resonance elastography (MRE) was developed on the basis of a desire to "palpate by imaging" and is becoming a powerful tool in the investigation of neurophysiological and neuropathological states. Measurements are acquired with a specialized MR phase-contrast pulse sequence that can detect tissue motion in response to an applied external or internal excitation. The tissue viscoelasticity is then reconstructed from the measured displacement. Quantitative characterization of brain viscoelastic behaviors provides us an insight into the brain structure and function by assessing the mechanical rigidity, viscosity, friction, and connectivity of brain tissues. Changes in these features are associated with inflammation, demyelination, and neurodegeneration that contribute to brain disease onset and progression. Here, we review the basic principles and limitations of brain MRE and summarize its current neuroanatomical studies and clinical applications to the most common neurosurgical and neurodegenerative disorders, including intracranial tumors, dementia, multiple sclerosis, amyotrophic lateral sclerosis, and traumatic brain injury. Going forward, further improvement in acquisition techniques, stable inverse reconstruction algorithms, and advanced numerical, physical, and preclinical validation models is needed to increase the utility of brain MRE in both research and clinical applications.
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Affiliation(s)
- Ziying Yin
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN
| | | | - Armando Manduca
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN
- Departments of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN
| | - Richard L. Ehman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN
| | - John Huston
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN
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Shin SS, Huisman TAGM, Hwang M. Ultrasound Imaging for Traumatic Brain Injury. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2018; 37:1857-1867. [PMID: 29388231 DOI: 10.1002/jum.14547] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/17/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Traumatic brain injury (TBI) is challenging to assess even with recent advancements in computed tomography and magnetic resonance imaging. Ultrasound (US) imaging has previously been less utilized in TBI compared to conventional imaging because of limited resolution in the intracranial space. However, there have been substantial improvements in contrast-enhanced US and development of novel techniques such as intravascular US. Also, continued research provides further insight into cerebrovascular parameters from transcranial Doppler imaging. These advancements in US imaging provides the community of TBI imaging researchers and clinicians new opportunities in clinically monitoring and understanding the pathologic mechanisms of TBI.
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Affiliation(s)
- Samuel S Shin
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Thierry A G M Huisman
- Division of Pediatric Radiology and Pediatric Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Misun Hwang
- Division of Pediatric Radiology and Pediatric Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Bayly PV, Garbow JR. Pre-clinical MR elastography: Principles, techniques, and applications. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 291:73-83. [PMID: 29705042 PMCID: PMC5943171 DOI: 10.1016/j.jmr.2018.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 01/07/2018] [Indexed: 05/09/2023]
Abstract
Magnetic resonance elastography (MRE) is a method for measuring the mechanical properties of soft tissue in vivo, non-invasively, by imaging propagating shear waves in the tissue. The speed and attenuation of waves depends on the elastic and dissipative properties of the underlying material. Tissue mechanical properties are essential for biomechanical models and simulations, and may serve as markers of disease, injury, development, or recovery. MRE is already established as a clinical technique for detecting and characterizing liver disease. The potential of MRE for diagnosing or characterizing disease in other organs, including brain, breast, and heart is an active research area. Studies involving MRE in the pre-clinical setting, in phantoms and artificial biomaterials, in the mouse, and in other mammals, are critical to the development of MRE as a robust, reliable, and useful modality.
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Affiliation(s)
- P V Bayly
- Mechanical Engineering and Materials Science, Washington University in Saint Louis, MO, USA.
| | - J R Garbow
- Radiology, Washington University School of Medicine, Saint Louis, MO, USA
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19
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Feng Y, Gao Y, Wang T, Tao L, Qiu S, Zhao X. A longitudinal study of the mechanical properties of injured brain tissue in a mouse model. J Mech Behav Biomed Mater 2017; 71:407-415. [DOI: 10.1016/j.jmbbm.2017.04.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/30/2017] [Accepted: 04/06/2017] [Indexed: 12/11/2022]
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Bosshard JC, Yallapragada N, McDougall MP, Wright SM. Exploration of highly accelerated magnetic resonance elastography using high-density array coils. Quant Imaging Med Surg 2017; 7:195-204. [PMID: 28516045 PMCID: PMC5418148 DOI: 10.21037/qims.2017.04.02] [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: 03/25/2017] [Accepted: 04/07/2017] [Indexed: 11/06/2022]
Abstract
BACKGROUND Magnetic resonance elastography (MRE) measures tissue mechanical properties by applying a shear wave and capturing its propagation using magnetic resonance imaging (MRI). By using high density array coils, MRE images are acquired using single echo acquisition (SEA) and at high resolutions with significantly reduced scan times. METHODS Sixty-four channel uniplanar and 32×32 channel biplanar receive arrays are used to acquire MRE wave image sets from agar samples containing regions of varying stiffness. A mechanical actuator triggered by a stepped delay time introduces vibrations into the sample while a motion sensitizing gradient encodes micrometer displacements into the phase. SEA imaging is used to acquire each temporal offset in a single echo, while multiple echoes from the same array are employed for highly accelerated imaging at high resolutions. Additionally, stiffness variations as a function of temperature are studied by using a localized heat source above the sample. A custom insertable gradient coil is employed for phase compensation of SEA imaging with the biplanar array to allow imaging of multiple slices. RESULTS SEA MRE images show a mechanical shear wave propagating into and across agar samples. A set of 720 images was obtained in 720 echoes, plus a single reference scan for both harmonic and transient MRE. A set of 2,950 wave image frames was acquired from pairs of SEA images captured during heating, showing the change in mechanical wavelength with the change in agar properties. A set of 240 frames was acquired from two slices simultaneously using the biplanar array, with phase images processed into displacement maps. Combining the narrow sensitivity patterns and SNR advantage of the SEA array coil geometry allowed acquisition of a data set with a resolution of 156 µm × 125 µm × 1,000 µm in only 64 echoes, demonstrating high resolution and high acceleration factors. CONCLUSIONS MRE using high-density arrays offers the unique ability to acquire a single frame of a propagating mechanical vibration with each echo, which may be helpful in non-repeatable or destructive testing. Highly accelerated, high resolution MRE may be enabled by the use of large arrays of coils such as used for SEA, but at lower acceleration rates supporting the higher resolution than provided by SEA imaging.
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Affiliation(s)
- John C. Bosshard
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Naresh Yallapragada
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Mary P. McDougall
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Steven M. Wright
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- Department of Radiology, Texas A&M Health Science Center, Bryan, TX, USA
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21
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Lucke-Wold BP, Phillips M, Turner RC, Logsdon AF, Smith KE, Huber JD, Rosen CL, Regele JD. Elucidating the role of compression waves and impact duration for generating mild traumatic brain injury in rats. Brain Inj 2017; 31:98-105. [PMID: 27880054 PMCID: PMC5247354 DOI: 10.1080/02699052.2016.1218547] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND In total, 3.8 million concussions occur each year in the US leading to acute functional deficits, but the underlying histopathologic changes that occur are relatively unknown. In order to improve understanding of acute injury mechanisms, appropriately designed pre-clinical models must be utilized. METHODS The clinical relevance of compression wave injury models revolves around the ability to produce consistent histopathologic deficits. Mild traumatic brain injuries activate similar neuroinflammatory cascades, cell death markers and increases in amyloid precursor protein in both humans and rodents. Humans, however, infrequently succumb to mild traumatic brain injuries and, therefore, the intensity and magnitude of impacts must be inferred. Understanding compression wave properties and mechanical loading could help link the histopathologic deficits seen in rodents to what might be happening in human brains following concussions. RESULTS While the concept of linking duration and intensity of impact to subsequent histopathologic deficits makes sense, numerical modelling of compression waves has not been performed in this context. In this interdisciplinary work, numerical simulations were performed to study the creation of compression waves in an experimental model. CONCLUSION This work was conducted in conjunction with a repetitive compression wave injury paradigm in rats in order to better understand how the wave generation correlates with histopathologic deficits.
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Affiliation(s)
- Brandon P Lucke-Wold
- a Department of Neurosurgery
- b Center for Neuroscience, School of Medicine , West Virginia University , Morgantown , WV , USA
| | - Michael Phillips
- c Department of Aerospace Engineering , College of Engineering, Iowa State University , Ames , IA , USA
| | | | - Aric F Logsdon
- b Center for Neuroscience, School of Medicine , West Virginia University , Morgantown , WV , USA
- d Department of Pharmaceutical Sciences , School of Pharmacy, West Virginia University , Morgantown , WV , USA
| | - Kelly E Smith
- b Center for Neuroscience, School of Medicine , West Virginia University , Morgantown , WV , USA
- d Department of Pharmaceutical Sciences , School of Pharmacy, West Virginia University , Morgantown , WV , USA
| | - Jason D Huber
- d Department of Pharmaceutical Sciences , School of Pharmacy, West Virginia University , Morgantown , WV , USA
| | | | - Jonathan D Regele
- c Department of Aerospace Engineering , College of Engineering, Iowa State University , Ames , IA , USA
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22
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Bartlett RD, Choi D, Phillips JB. Biomechanical properties of the spinal cord: implications for tissue engineering and clinical translation. Regen Med 2016; 11:659-73. [DOI: 10.2217/rme-2016-0065] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Spinal cord injury is a severely debilitating condition which can leave individuals paralyzed and suffering from autonomic dysfunction. Regenerative medicine may offer a promising solution to this problem. Previous research has focused primarily on exploring the cellular and biological aspects of the spinal cord, yet relatively little remains known about the biomechanical properties of spinal cord tissue. Given that a number of regenerative strategies aim to deliver cells and materials in the form of tissue-engineered therapies, understanding the biomechanical properties of host spinal cord tissue is important. We review the relevant biomechanical properties of spinal cord tissue and provide the baseline knowledge required to apply these important physical concepts to spinal cord tissue engineering.
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Affiliation(s)
- Richard D Bartlett
- Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
- Brain Repair & Rehabilitation, Institute of Neurology, University College London, London, UK
| | - David Choi
- Brain Repair & Rehabilitation, Institute of Neurology, University College London, London, UK
| | - James B Phillips
- Biomaterials & Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK
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Low G, Kruse SA, Lomas DJ. General review of magnetic resonance elastography. World J Radiol 2016; 8:59-72. [PMID: 26834944 PMCID: PMC4731349 DOI: 10.4329/wjr.v8.i1.59] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/14/2015] [Accepted: 12/04/2015] [Indexed: 02/06/2023] Open
Abstract
Magnetic resonance elastography (MRE) is an innovative imaging technique for the non-invasive quantification of the biomechanical properties of soft tissues via the direct visualization of propagating shear waves in vivo using a modified phase-contrast magnetic resonance imaging (MRI) sequence. Fundamentally, MRE employs the same physical property that physicians utilize when performing manual palpation - that healthy and diseased tissues can be differentiated on the basis of widely differing mechanical stiffness. By performing “virtual palpation”, MRE is able to provide information that is beyond the capabilities of conventional morphologic imaging modalities. In an era of increasing adoption of multi-parametric imaging approaches for solving complex problems, MRE can be seamlessly incorporated into a standard MRI examination to provide a rapid, reliable and comprehensive imaging evaluation at a single patient appointment. Originally described by the Mayo Clinic in 1995, the technique represents the most accurate non-invasive method for the detection and staging of liver fibrosis and is currently performed in more than 100 centers worldwide. In this general review, the mechanical properties of soft tissues, principles of MRE, clinical applications of MRE in the liver and beyond, and limitations and future directions of this discipline -are discussed. Selected diagrams and images are provided for illustration.
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Amyot F, Arciniegas DB, Brazaitis MP, Curley KC, Diaz-Arrastia R, Gandjbakhche A, Herscovitch P, Hinds SR, Manley GT, Pacifico A, Razumovsky A, Riley J, Salzer W, Shih R, Smirniotopoulos JG, Stocker D. A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury. J Neurotrauma 2015; 32:1693-721. [PMID: 26176603 PMCID: PMC4651019 DOI: 10.1089/neu.2013.3306] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The incidence of traumatic brain injury (TBI) in the United States was 3.5 million cases in 2009, according to the Centers for Disease Control and Prevention. It is a contributing factor in 30.5% of injury-related deaths among civilians. Additionally, since 2000, more than 260,000 service members were diagnosed with TBI, with the vast majority classified as mild or concussive (76%). The objective assessment of TBI via imaging is a critical research gap, both in the military and civilian communities. In 2011, the Department of Defense (DoD) prepared a congressional report summarizing the effectiveness of seven neuroimaging modalities (computed tomography [CT], magnetic resonance imaging [MRI], transcranial Doppler [TCD], positron emission tomography, single photon emission computed tomography, electrophysiologic techniques [magnetoencephalography and electroencephalography], and functional near-infrared spectroscopy) to assess the spectrum of TBI from concussion to coma. For this report, neuroimaging experts identified the most relevant peer-reviewed publications and assessed the quality of the literature for each of these imaging technique in the clinical and research settings. Although CT, MRI, and TCD were determined to be the most useful modalities in the clinical setting, no single imaging modality proved sufficient for all patients due to the heterogeneity of TBI. All imaging modalities reviewed demonstrated the potential to emerge as part of future clinical care. This paper describes and updates the results of the DoD report and also expands on the use of angiography in patients with TBI.
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Affiliation(s)
- Franck Amyot
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - David B. Arciniegas
- Beth K. and Stuart C. Yudofsky Division of Neuropsychiatry, Baylor College of Medicine, Houston, Texas
- Brain Injury Research, TIRR Memorial Hermann, Houston, Texas
| | | | - Kenneth C. Curley
- Combat Casualty Care Directorate (RAD2), U.S. Army Medical Research and Materiel Command, Fort Detrick, Maryland
| | - Ramon Diaz-Arrastia
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Amir Gandjbakhche
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Peter Herscovitch
- Positron Emission Tomography Department, National Institutes of Health Clinical Center, Bethesda, Maryland
| | - Sidney R. Hinds
- Defense and Veterans Brain Injury Center, Defense Centers of Excellence for Psychological Health and Traumatic Brain Injury Silver Spring, Maryland
| | - Geoffrey T. Manley
- Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Anthony Pacifico
- Congressionally Directed Medical Research Programs, Fort Detrick, Maryland
| | | | - Jason Riley
- Queens University, Kingston, Ontario, Canada
- ArcheOptix Inc., Picton, Ontario, Canada
| | - Wanda Salzer
- Congressionally Directed Medical Research Programs, Fort Detrick, Maryland
| | - Robert Shih
- Walter Reed National Military Medical Center, Bethesda, Maryland
| | - James G. Smirniotopoulos
- Department of Radiology, Neurology, and Biomedical Informatics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Derek Stocker
- Walter Reed National Military Medical Center, Bethesda, Maryland
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Suarez MW, Dever DD, Gu X, Ray Illian P, McClintic AM, Mehic E, Mourad PD. Transcranial vibro-acoustography can detect traumatic brain injury, in-vivo: Preliminary studies. ULTRASONICS 2015; 61:151-156. [PMID: 25964238 DOI: 10.1016/j.ultras.2015.04.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 04/21/2015] [Accepted: 04/25/2015] [Indexed: 06/04/2023]
Abstract
Vibro-acoustography (VA) uses two or more beams of confocal ultrasound to generate local vibrations within their target tissue through induction of a time-dependent radiation force whose frequency equals that of the difference of the applied frequencies. While VA has proven effective for assaying the mechanical properties of clinically relevant tissue such as breast lesions and tissue calcifications, its application to brain remains unexplored. Here we investigate the ability of VA to detect acute and focal traumatic brain injury (TBI) in-vivo through the use of transcranially delivered high-frequency (2 MHz) diagnostic focused ultrasound to rat brain capable of generating measurable low-frequency (200-270 kHz) acoustic emissions from outside of the brain. We applied VA to acute sham-control and TBI model rats (sham N=6; TBI N=6) and observed that acoustic emissions, captured away from the site of TBI, had lower amplitudes for TBI as compared to sham-TBI animals. The sensitivity of VA to acute brain damage at frequencies currently transmittable across human skulls, as demonstrated in this preliminary study, supports the possibility that the VA methodology may one day serve as a technique for detecting TBI.
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Affiliation(s)
- Martin W Suarez
- Department of Bioengineering, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States; Department of Neurological Surgery, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States
| | - David D Dever
- Department of Bioengineering, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States
| | - Xiaohan Gu
- Department of Bioengineering, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States
| | - P Ray Illian
- Applied Physics Laboratory, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States
| | - Abbi M McClintic
- Department of Neurological Surgery, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States
| | - Edin Mehic
- Department of Bioengineering, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States; Department of Neurological Surgery, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States
| | - Pierre D Mourad
- Department of Bioengineering, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States; Department of Neurological Surgery, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States; Applied Physics Laboratory, Univ. of WA, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States; Division of Engineering and Mathematics, Univ. of WA Bothell, 1959 NE Pacific St., Box 356470, Seattle, WA 98195, United States.
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Khalilzad-Sharghi V, Han Z, Xu H, Othman SF. MR elastography for evaluating regeneration of tissue-engineered cartilage in an ectopic mouse model. Magn Reson Med 2015; 75:1209-17. [PMID: 25918870 DOI: 10.1002/mrm.25745] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 12/20/2022]
Abstract
PURPOSE The purpose of the present study was to apply noninvasive methods for monitoring regeneration and mechanical properties of tissue-engineered cartilage in vivo at different growth stages using MR elastography (MRE). METHODS Three types of scaffolds, including silk, collagen, and gelatin seeded by human mesenchymal stem cells, were implanted subcutaneously in mice and imaged at 9.4T where the shear stiffness and transverse MR relaxation time (T2 ) were measured for the regenerating constructs for 8 wk. An MRE phase contrast spin echo-based sequence was used for collecting MRE images. At the conclusion of the in vivo study, constructs were excised and transcript levels of cartilage-specific genes were quantitated using reverse-transcription polymerase chain reaction. RESULTS Tissue-engineered constructs showed a cartilage-like construct with progressive tissue formation characterized by increase in shear stiffness and decrease in T2 that can be correlated with increased cartilage transcript levels including aggrecan, type II collagen, and cartilage oligomeric matrix protein after 8 wk of in vivo culture. CONCLUSION Altogether, the outcome of this research demonstrates the feasibility of MRE and MRI for noninvasive monitoring of engineered cartilage construct's growth after implantation and provides noninvasive biomarkers for regeneration, which may be translated into treatment of tissue defects.
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Affiliation(s)
- Vahid Khalilzad-Sharghi
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Zhongji Han
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Huihui Xu
- School of Engineering and Computer Science, University of the Pacific, Stockton, California, USA
| | - Shadi F Othman
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
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Xu ZS, Yao A, Chu SS, Paun MK, McClintic AM, Murphy SP, Mourad PD. Detection of mild traumatic brain injury in rodent models using shear wave elastography: preliminary studies. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2014; 33:1763-1771. [PMID: 25253822 DOI: 10.7863/ultra.33.10.1763] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
OBJECTIVES Traumatic brain injury (TBI) can cause adverse physiologic changes in fluid content within the brain, which may lead to changes in tissue elasticity (eg, stiffness). This study evaluated the ability of ultrasonic shear wave elastography to observe these changes in the brain after TBI in vivo. METHODS Mice and rats received a mild TBI or sham surgery and were imaged acutely or 24 hours after injury using shear wave elastography, and the hemispheric stiffness values were compared. RESULTS Stiffness values were consistent across brain hemispheres of sham TBI rodents. By 24 hours after TBI, relative brain tissue stiffness values for mice and rats each decreased ipsilaterally and increased contralaterally, both relative to each other and compared to sham TBI rodents (P < .05). The absolute tissue elasticity value increased for rats (P < .05) but not for mice. CONCLUSIONS Differences between intrahemispheric stiffness values of rodent brains by 24 hours after mild TBI may reflect the observed edema and hemorrhage ipsilateral to TBI and the known reduction of cerebral blood flow in both brain hemispheres. If these hypotheses hold true, ultrasonic shear wave elastography may offer a method for detecting adverse changes in fluid content within the brain after mild TBI.
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Affiliation(s)
- Zinnia S Xu
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA
| | - Anning Yao
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA
| | - Stephanie S Chu
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA
| | - Marla K Paun
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA
| | - Abbi M McClintic
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA
| | - Sean P Murphy
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA
| | - Pierre D Mourad
- Department of Bioengineering (Z.S.X., A.Y., S.S.C., P.D.M.), Applied Physics Laboratory (M.K.P., P.D.M.), and Department of Neurological Surgery (A.M.M., S.P.M., P.D.M.), University of Washington, Seattle, Washington USA.
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Meaney DF, Morrison B, Dale Bass C. The mechanics of traumatic brain injury: a review of what we know and what we need to know for reducing its societal burden. J Biomech Eng 2014; 136:021008. [PMID: 24384610 PMCID: PMC4023660 DOI: 10.1115/1.4026364] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/20/2013] [Accepted: 12/27/2013] [Indexed: 12/25/2022]
Abstract
Traumatic brain injury (TBI) is a significant public health problem, on pace to become the third leading cause of death worldwide by 2020. Moreover, emerging evidence linking repeated mild traumatic brain injury to long-term neurodegenerative disorders points out that TBI can be both an acute disorder and a chronic disease. We are at an important transition point in our understanding of TBI, as past work has generated significant advances in better protecting us against some forms of moderate and severe TBI. However, we still lack a clear understanding of how to study milder forms of injury, such as concussion, or new forms of TBI that can occur from primary blast loading. In this review, we highlight the major advances made in understanding the biomechanical basis of TBI. We point out opportunities to generate significant new advances in our understanding of TBI biomechanics, especially as it appears across the molecular, cellular, and whole organ scale.
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Affiliation(s)
- David F. Meaney
- Departments of Bioengineeringand Neurosurgery,University of Pennsylvania,Philadelphia, PA 19104-6392e-mail:
| | - Barclay Morrison
- Department of Biomedical Engineering,Columbia University,New York, NY 10027
| | - Cameron Dale Bass
- Department of Biomedical Engineering,Duke University,Durham, NC 27708-0281
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Alfasi AM, Shulyakov AV, Del Bigio MR. Intracranial biomechanics following cortical contusion in live rats. J Neurosurg 2013; 119:1255-62. [DOI: 10.3171/2013.7.jns121973] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Object
The goal of this study was to examine the mechanical properties of living rat intracranial contents and corresponding brain structural alterations following parietal cerebral cortex contusion.
Methods
After being anesthetized, young adult rats were subjected to parietal craniotomy followed by cortical contusion using a calibrated weight-drop method. Magnetic resonance imaging was used to visualize the contusion. At the site of contusion, instrumented force-controlled indentation was performed 2 hours to 21 days later on the intact dural surface. The force-deformation (stress-strain) relationship was used to calculate elastic (indentation modulus) and strain changes over time, and constant hold or cyclic stress was used to evaluate viscoelastic deformation. These measurements were followed by histological studies.
Results
At contusion sites, the indentation modulus was significantly decreased at 1–3 days and tended to be above control values at 21 days. Multicycle indentation showed that the brain tended to accumulate more strain (an indicator of viscosity) by 1 day after the contusion. Imaging and histological studies showed local edema and hemorrhage at 6 hours to 3 days and accumulation of reactive astrocytes, which began at 3 days and was pronounced by 21 days.
Conclusions
The viscoelastic properties of living rat brain change following contusion. Initially, edema and tissue necrosis occur, and the brain becomes less elastic and less viscous. Later, along with undergoing reactive astroglial changes, the brain tends to become stiffer than normal. These quantitative data, which are related to the physical changes in the brain following trauma and which reflect subjective impressions upon palpation, will be useful for understanding emerging diagnostic tools such as magnetic resonance elastography.
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Affiliation(s)
| | | | - Marc R. Del Bigio
- 2Pathology, University of Manitoba, Winnipeg, Canada
- 3Manitoba Institute of Child Health, Winnipeg, Canada
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Othman SF, Xu H, Mao JJ. Future role of MR elastography in tissue engineering and regenerative medicine. J Tissue Eng Regen Med 2013; 9:481-7. [PMID: 23956239 DOI: 10.1002/term.1801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 01/23/2023]
Abstract
Tissue engineering (TE) has been introduced for more than 25 years without a boom in clinical trials. More than 70 TE-related start-up companies spent more than $600 million/year, with only two FDA-approved tissue-engineered products. Given the modest performance in clinically approved organs, TE is a tenaciously promising field. The TE community is advocating the application of clinically driven methodologies in large animal models enabling clinical translation. This challenge is hindered by the scarcity of tissue biopsies and the absence of standardized evaluation tools, but can be negated through non-invasive assessment of growth and integration, with reduced sample size and low cost. Solving this issue will speed the transition to cost-efficient clinical studies. In this paper we: (a) introduce magnetic resonance elastography to the tissue-engineering and regenerative medicine (TERM) community; (b) review recent MRE applications in TERM; and (c) discuss future directions of MRE in TERM. We have used MRE to study engineered tissues both in vitro and in vivo, where the mechanical properties of mesenchymally derived constructs were progressively monitored before and after tissues were implanted in mouse models. This study represents a stepping stone toward the applications of MRE in directing clinical trials with low cost and likely expediting the translation to more relevantly large animal models and clinical trials.
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Affiliation(s)
- Shadi F Othman
- Tissue Engineering and Regenerative Medicine Laboratory, University of Nebraska, Lincoln, NE, USA
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Boulet T, Kelso ML, Othman SF. Long-term in vivo imaging of viscoelastic properties of the mouse brain after controlled cortical impact. J Neurotrauma 2013; 30:1512-20. [PMID: 23534701 DOI: 10.1089/neu.2012.2788] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) presents a variety of causes and symptoms, thus making the development of reliable diagnostic methods and therapeutic treatments challenging. Magnetic resonance elastography (MRE) is a technique that allows for a noninvasive assessment of the mechanical properties of soft biological tissue, such as tissue stiffness, storage modulus, and loss modulus. Importantly, by quantifying the changes in the stiffness of tissue that is often associated with disease, MRE is able to detect tissue pathologies at early stages. Recent improvements in instrumentation have allowed for the investigation of small samples with microscopic resolution (μMRE). We hypothesize that μMRE can sensitively detect variations in micromechanical properties in the brain caused by the compressive and shearing forces sustained during TBI. To test this hypothesis, we randomized 13 C57BL mice to receive a controlled cortical impact at a 0.5 mm or 0.75 mm depth, with both sham and naïve mice as controls. Our objective was to propagate mechanical shear waves throughout the brain for in vivo TBI μMRE imaging. The mechanical properties of the injured brain tissue were determined at days 0, 1, 7, and 28 post-injury. For both groups, we observed a significant drop in the stiffness of the impacted region immediately following the injury; the 0.75 mm animals experienced increased tissue softness that lasted longer than that for the 0.5 mm group. Although the shear stiffness, storage modulus, and loss modulus parameters all followed the same trend, the tissue stiffness yielded the most statistically significant results. Overall, this article introduces a transformative technique for mechanically mapping the brain and detecting brain diseases and injury.
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Affiliation(s)
- Thomas Boulet
- Department of Engineering Mechanics, University of Nebraska-Lincoln, Lincoln, Nebraksa 43353, USA
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Abstract
Biological cells are well known to respond to a multitude of chemical signals. In the nervous system, chemical signaling has been shown to be crucially involved in development, normal functioning, and disorders of neurons and glial cells. However, there are an increasing number of studies showing that these cells also respond to mechanical cues. Here, we summarize current knowledge about the mechanical properties of nervous tissue and its building blocks, review recent progress in methodology and understanding of cellular mechanosensitivity in the nervous system, and provide an outlook on the implications of neuromechanics for future developments in biomedical engineering to aid overcoming some of the most devastating and currently incurable CNS pathologies such as spinal cord injuries and multiple sclerosis.
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Affiliation(s)
- Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
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Feng Y, Clayton EH, Chang Y, Okamoto RJ, Bayly PV. Viscoelastic properties of the ferret brain measured in vivo at multiple frequencies by magnetic resonance elastography. J Biomech 2013; 46:863-70. [PMID: 23352648 DOI: 10.1016/j.jbiomech.2012.12.024] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 12/03/2012] [Accepted: 12/21/2012] [Indexed: 11/16/2022]
Abstract
Characterization of the dynamic mechanical behavior of brain tissue is essential for understanding and simulating the mechanisms of traumatic brain injury (TBI). Changes in mechanical properties may also reflect changes in the brain due to aging or disease. In this study, we used magnetic resonance elastography (MRE) to measure the viscoelastic properties of ferret brain tissue in vivo. Three-dimensional (3D) displacement fields were acquired during wave propagation in the brain induced by harmonic excitation of the skull at 400 Hz, 600 Hz and 800 Hz. Shear waves with wavelengths in the order of millimeters were clearly visible in the displacement field, in strain fields, and in the curl of displacement field (which contains no contributions from longitudinal waves). Viscoelastic parameters (storage and loss moduli) governing dynamic shear deformation were estimated in gray and white matter for these excitation frequencies. To characterize the reproducibility of measurements, two ferrets were studied on three different dates each. Estimated viscoelastic properties of white matter in the ferret brain were generally similar to those of gray matter and consistent between animals and scan dates. In both tissue types G' increased from approximately 3 kPa at 400 Hz to 7 kPa at 800 Hz and G″ increased from approximately 1 kPa at 400 Hz to 2 kPa at 800 Hz. These measurements of shear wave propagation in the ferret brain can be used to both parameterize and validate finite element models of brain biomechanics.
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Affiliation(s)
- Y Feng
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63130, USA
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Abstract
All cells are influenced by mechanical forces. In the brain, force-generating and load-bearing proteins twist, turn, ratchet, flex, compress, expand and bend to mediate neuronal signalling and plasticity. Although the functions of mechanosensitive proteins have been thoroughly described in classical sensory systems, the effects of endogenous mechanical energy on cellular function in the brain have received less attention, and many working models in neuroscience do not currently integrate principles of cellular mechanics. An understanding of cellular-mechanical concepts is essential to allow the integration of mechanobiology into ongoing studies of brain structure and function.
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Toledo E, Lebel A, Becerra L, Minster A, Linnman C, Maleki N, Dodick DW, Borsook D. The young brain and concussion: imaging as a biomarker for diagnosis and prognosis. Neurosci Biobehav Rev 2012; 36:1510-31. [PMID: 22476089 PMCID: PMC3372677 DOI: 10.1016/j.neubiorev.2012.03.007] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/15/2012] [Accepted: 03/21/2012] [Indexed: 01/20/2023]
Abstract
Concussion (mild traumatic brain injury (mTBI)) is a significant pediatric public health concern. Despite increased awareness, a comprehensive understanding of the acute and chronic effects of concussion on central nervous system structure and function remains incomplete. Here we review the definition, epidemiology, and sequelae of concussion within the developing brain, during childhood and adolescence, with current data derived from studies of pathophysiology and neuroimaging. These findings may contribute to a better understanding of the neurological consequences of traumatic brain injuries, which in turn, may lead to the development of brain biomarkers to improve identification, management and prognosis of pediatric patients suffering from concussion.
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Affiliation(s)
- Esteban Toledo
- Center for Pain and the Brain, Children's Hospital Boston, Harvard Medical School, United States
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