1
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Ge GR, Song W, Giannetto MJ, Rolland JP, Nedergaard M, Parker KJ. Mouse brain elastography changes with sleep/wake cycles, aging, and Alzheimer's disease. Neuroimage 2024; 295:120662. [PMID: 38823503 DOI: 10.1016/j.neuroimage.2024.120662] [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: 02/27/2024] [Revised: 05/05/2024] [Accepted: 05/30/2024] [Indexed: 06/03/2024] Open
Abstract
Understanding the physiological processes in aging and how neurodegenerative disorders affect cognitive function is a high priority for advancing human health. One specific area of recently enabled research is the in vivo biomechanical state of the brain. This study utilized reverberant optical coherence elastography, a high-resolution elasticity imaging method, to investigate stiffness changes during the sleep/wake cycle, aging, and Alzheimer's disease in murine models. Four-dimensional scans of 44 wildtype mice, 13 mice with deletion of aquaporin-4 water channel, and 12 mice with Alzheimer-related pathology (APP/PS1) demonstrated that (1) cortical tissue became softer (on the order of a 10% decrease in shear wave speed) when young wildtype mice transitioned from wake to anesthetized, yet this effect was lost in aging and with mice overexpressing amyloid-β or lacking the water channel AQP4. (2) Cortical stiffness increased with age in all mice lines, but wildtype mice exhibited the most prominent changes as a function of aging. The study provides novel insight into the brain's biomechanics, the constraints of fluid flow, and how the state of brain activity affects basic properties of cortical tissues.
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Affiliation(s)
- Gary R Ge
- The Institute of Optics, University of Rochester, 480 Intercampus Drive, Rochester, NY 14627, USA
| | - Wei Song
- Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Michael J Giannetto
- Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Jannick P Rolland
- The Institute of Optics, University of Rochester, 480 Intercampus Drive, Rochester, NY 14627, USA; Department of Biomedical Engineering, University of Rochester, 204 Robert B. Goergen Hall, Rochester, NY 14627, USA; Center for Visual Science, University of Rochester, 361 Meliora Hall, Rochester, NY 14627, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA; Center for Translational Neuromedicine, University of Copenhagen, Blegdamsvej 3B, 2200-N, Denmark.
| | - Kevin J Parker
- Department of Biomedical Engineering, University of Rochester, 204 Robert B. Goergen Hall, Rochester, NY 14627, USA; Department of Electrical and Computer Engineering, University of Rochester, 500 Computer Studies Building, Rochester, NY 14627, USA; Department of Imaging Sciences (Radiology), University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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2
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Wang S, Eckstein KN, Guertler CA, Johnson CL, Okamoto RJ, McGarry MD, Bayly PV. Post-mortem changes of anisotropic mechanical properties in the porcine brain assessed by MR elastography. BRAIN MULTIPHYSICS 2024; 6:100091. [PMID: 38933498 PMCID: PMC11207183 DOI: 10.1016/j.brain.2024.100091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024] Open
Abstract
Knowledge of the mechanical properties of brain tissue in vivo is essential to understanding the mechanisms underlying traumatic brain injury (TBI) and to creating accurate computational models of TBI and neurosurgical simulation. Brain white matter, which is composed of aligned, myelinated, axonal fibers, is structurally anisotropic. White matter in vivo also exhibits mechanical anisotropy, as measured by magnetic resonance elastography (MRE), but measurements of anisotropy obtained by mechanical testing of white matter ex vivo have been inconsistent. The minipig has a gyrencephalic brain with similar white matter and gray matter proportions to humans and therefore provides a relevant model for human brain mechanics. In this study, we compare estimates of anisotropic mechanical properties of the minipig brain obtained by identical, non-invasive methods in the live (in vivo) and dead animals (in situ). To do so, we combine wave displacement fields from MRE and fiber directions derived from diffusion tensor imaging (DTI) with a finite element-based, transversely-isotropic nonlinear inversion (TI-NLI) algorithm. Maps of anisotropic mechanical properties in the minipig brain were generated for each animal alive and at specific times post-mortem. These maps show that white matter is stiffer, more dissipative, and more anisotropic than gray matter when the minipig is alive, but that these differences largely disappear post-mortem, with the exception of tensile anisotropy. Overall, brain tissue becomes stiffer, less dissipative, and less mechanically anisotropic post-mortem. These findings emphasize the importance of testing brain tissue properties in vivo. Statement of Significance In this study, MRE and DTI in the minipig were combined to estimate, for the first time, anisotropic mechanical properties in the living brain and in the same brain after death. Significant differences were observed in the anisotropic behavior of brain tissue post-mortem. These results demonstrate the importance of measuring brain tissue properties in vivo as well as ex vivo, and provide new quantitative data for the development of computational models of brain biomechanics.
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Affiliation(s)
- Shuaihu Wang
- Washington University in St. Louis, Mechanical Engineering and Material Science, United States
| | - Kevin N. Eckstein
- Washington University in St. Louis, Mechanical Engineering and Material Science, United States
| | - Charlotte A. Guertler
- Washington University in St. Louis, Mechanical Engineering and Material Science, United States
| | | | - Ruth J. Okamoto
- Washington University in St. Louis, Mechanical Engineering and Material Science, United States
| | | | - Philip V. Bayly
- Washington University in St. Louis, Mechanical Engineering and Material Science, United States
- Washington University in St. Louis, Biomedical Engineering, United States
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3
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Zhang N, Zhang Y. Correlation between gyral size, brain size, and head impact risk across mammalian species. Brain Res 2024; 1828:148768. [PMID: 38244756 DOI: 10.1016/j.brainres.2024.148768] [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: 09/27/2023] [Revised: 12/12/2023] [Accepted: 01/12/2024] [Indexed: 01/22/2024]
Abstract
A study on primates has established that gyral size is largely independent of overall brain size. Building on this-and other research suggesting that brain gyrification may mitigate the effects of head impacts-our study aims to explore potential correlations between gyral size and the risk of head impact across a diverse range of mammalian species. Our findings corroborate the idea that gyral sizes are largely independent of brain sizes, especially among species with larger brains, thus extending this observation beyond primates. Preliminary evidence also suggests a correlation between an animal's gyral size and its lifestyle, particularly in terms of head-impact risk. For instance, goats, known for their headbutting behaviors, exhibit smaller gyral sizes. In contrast, species such as manatees and dugongs, which typically face lower risks of head impact, have lissencephalic brains. Additionally, we explore mechanisms that may explain how narrower gyral sizes could offer protective advantages against head impact. Finally, we discuss a possible trade-off associated with gyrencephaly.
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Affiliation(s)
- Nianqin Zhang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Yongjun Zhang
- Science College, Liaoning Technical University, Fuxin 123000, China.
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4
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Chandrasekaran S, Santibanez F, Long T, Nichols T, Kait J, Bruegge RV, 'Dale' Bass CR, Pinton G. Shear shock wave injury in vivo: High frame-rate ultrasound observation and histological assessment. J Biomech 2024; 166:112021. [PMID: 38479150 DOI: 10.1016/j.jbiomech.2024.112021] [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: 01/13/2023] [Revised: 02/14/2024] [Accepted: 02/20/2024] [Indexed: 04/13/2024]
Abstract
Using high frame-rate ultrasound and ¡1μm sensitive motion tracking we previously showed that shear waves at the surface of ex vivo and in situ brains develop into shear shock waves deep inside the brain, with destructive local accelerations. However post-mortem tissue cannot develop injuries and has different viscoelastodynamic behavior from in vivo tissue. Here we present the ultrasonic measurement of the high-rate shear shock biomechanics in the in vivo porcine brain, and histological assessment of the resulting axonal pathology. A new biomechanical model of brain injury was developed consisting of a perforated mylar surface attached to the brain and vibrated using an electromechanical shaker. Using a custom sequence with 8 interleaved wide beam emissions, brain imaging and motion tracking were performed at 2900 images/s. Shear shock waves were observed for the first time in vivo wherein the shock acceleration was measured to be 2.6 times larger than the surface acceleration ( 95g vs. 36g). Histopathology showed axonal damage in the impacted side of the brain from the brain surface, accompanied by a local shock-front acceleration of >70g. This shows that axonal injury occurs deep in the brain even though the shear excitation was at the brain surface, and the acceleration measurements support the hypothesis that shear shock waves are responsible for deep traumatic brain injuries.
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Affiliation(s)
| | - Francisco Santibanez
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, NC, USA
| | - Tyler Long
- Departments of Medicine and Pathology and Laboratory Medicine at University of North Carolina at Chapel Hill, USA
| | - Tim Nichols
- Departments of Medicine and Pathology and Laboratory Medicine at University of North Carolina at Chapel Hill, USA
| | - Jason Kait
- Department of Biomedical Engineering, Duke University, USA
| | - Ruth Vorder Bruegge
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, NC, USA
| | | | - Gianmarco Pinton
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, NC, USA.
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5
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Okamoto RJ, Escarcega JD, Alshareef A, Carass A, Prince JL, Johnson CL, Bayly PV. Effect of Direction and Frequency of Skull Motion on Mechanical Vulnerability of the Human Brain. J Biomech Eng 2023; 145:111005. [PMID: 37432674 PMCID: PMC10578077 DOI: 10.1115/1.4062937] [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: 12/21/2022] [Revised: 06/26/2023] [Accepted: 07/06/2023] [Indexed: 07/12/2023]
Abstract
Strain energy and kinetic energy in the human brain were estimated by magnetic resonance elastography (MRE) during harmonic excitation of the head, and compared to characterize the effect of loading direction and frequency on brain deformation. In brain MRE, shear waves are induced by external vibration of the skull and imaged by a modified MR imaging sequence; the resulting harmonic displacement fields are typically "inverted" to estimate mechanical properties, like stiffness or damping. However, measurements of tissue motion from MRE also illuminate key features of the response of the brain to skull loading. In this study, harmonic excitation was applied in two different directions and at five different frequencies from 20 to 90 Hz. Lateral loading induced primarily left-right head motion and rotation in the axial plane; occipital loading induced anterior-posterior head motion and rotation in the sagittal plane. The ratio of strain energy to kinetic energy (SE/KE) depended strongly on both direction and frequency. The ratio of SE/KE was approximately four times larger for lateral excitation than for occipital excitation and was largest at the lowest excitation frequencies studied. These results are consistent with clinical observations that suggest lateral impacts are more likely to cause injury than occipital or frontal impacts, and also with observations that the brain has low-frequency (∼10 Hz) natural modes of oscillation. The SE/KE ratio from brain MRE is potentially a simple and powerful dimensionless metric of brain vulnerability to deformation and injury.
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Affiliation(s)
- Ruth J. Okamoto
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, One Brookings Drive, MSC 1185-208-125, St. Louis, MO 63130
| | - Jordan D. Escarcega
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63130
| | - Ahmed Alshareef
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817
| | - Aaron Carass
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Jerry L. Prince
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218
| | - Curtis L. Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19713
| | - Philip V. Bayly
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63130
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6
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Wang S, Guertler CA, Okamoto RJ, Johnson CL, McGarry MDJ, Bayly PV. Mechanical stiffness and anisotropy measured by MRE during brain development in the minipig. Neuroimage 2023; 277:120234. [PMID: 37369255 PMCID: PMC11081136 DOI: 10.1016/j.neuroimage.2023.120234] [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: 02/15/2023] [Revised: 05/12/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
The relationship between brain development and mechanical properties of brain tissue is important, but remains incompletely understood, in part due to the challenges in measuring these properties longitudinally over time. In addition, white matter, which is composed of aligned, myelinated, axonal fibers, may be mechanically anisotropic. Here we use data from magnetic resonance elastography (MRE) and diffusion tensor imaging (DTI) to estimate anisotropic mechanical properties in six female Yucatan minipigs at ages from 3 to 6 months. Fiber direction was estimated from the principal axis of the diffusion tensor in each voxel. Harmonic shear waves in the brain were excited by three different configurations of a jaw actuator and measured using a motion-sensitive MR imaging sequence. Anisotropic mechanical properties are estimated from displacement field and fiber direction data with a finite element- based, transversely-isotropic nonlinear inversion (TI-NLI) algorithm. TI-NLI finds spatially resolved TI material properties that minimize the error between measured and simulated displacement fields. Maps of anisotropic mechanical properties in the minipig brain were generated for each animal at all four ages. These maps show that white matter is more dissipative and anisotropic than gray matter, and reveal significant effects of brain development on brain stiffness and structural anisotropy. Changes in brain mechanical properties may be a fundamental biophysical signature of brain development.
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Affiliation(s)
- Shuaihu Wang
- Mechanical Engineering and Material Science, Washington University in St. Louis, United States
| | - Charlotte A Guertler
- Mechanical Engineering and Material Science, Washington University in St. Louis, United States
| | - Ruth J Okamoto
- Mechanical Engineering and Material Science, Washington University in St. Louis, United States
| | | | | | - Philip V Bayly
- Mechanical Engineering and Material Science, Washington University in St. Louis, United States; Biomedical Engineering, Washington University in St. Louis, United States.
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7
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Carmo GP, Dymek M, Ptak M, Alves-de-Sousa RJ, Fernandes FAO. Development, validation and a case study: The female finite element head model (FeFEHM). COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 231:107430. [PMID: 36827824 DOI: 10.1016/j.cmpb.2023.107430] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/18/2023] [Accepted: 02/16/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND AND OBJECTIVE Traumatic brain injuries are one of the leading causes of death and disability in the world. To better understand the interactions and forces applied in different constituents of the human head, several finite element head models have been developed throughout the years, for offering a good cost-effective and ethical approach compared to experimental tests. Once validated, the female finite element head model (FeFEHM) will allow a better understanding of injury mechanisms resulting in neuronal damage, which can later evolve into neurodegenerative diseases. METHODS This work encompasses the approached methodology starting from medical images and finite element modelling until the validation process using novel experimental data of brain displacements conducted on human cadavers. The material modelling of the brain is performed using an age-specific characterization of the brain using microindentation at dynamic rates and under large deformation, with a similar age to the patient used to model the FeFEHM. RESULTS The numerical displacement curves are in good accordance with the experimental data, displaying similar peak times and values, in all three anatomical planes. The case study result shows a similarity between the pressure fields of the FeFEHM compared to another model, highlighting the future potential of the model. CONCLUSIONS The initial objective was met, and a new female finite element head model has been developed with biofidelic brain motion. This model will be used for the assessment of repetitive impact scenarios and its repercussions on the female brain.
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Affiliation(s)
- Gustavo P Carmo
- Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, Campus Universitário de Santiago, University of Aveiro, Aveiro 3810-193, Portugal; LASI-Intelligent Systems Associate Laboratory, Portugal.
| | - Mateusz Dymek
- Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Łukasiewicza 5/7, Wrocław 50-370, Poland
| | - Mariusz Ptak
- Faculty of Mechanical Engineering, Wroclaw University of Science and Technology, Łukasiewicza 5/7, Wrocław 50-370, Poland
| | - Ricardo J Alves-de-Sousa
- Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, Campus Universitário de Santiago, University of Aveiro, Aveiro 3810-193, Portugal; LASI-Intelligent Systems Associate Laboratory, Portugal
| | - Fábio A O Fernandes
- Centre for Mechanical Technology and Automation (TEMA), Department of Mechanical Engineering, Campus Universitário de Santiago, University of Aveiro, Aveiro 3810-193, Portugal; LASI-Intelligent Systems Associate Laboratory, Portugal
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8
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Kabir IE, Caban-Rivera DA, Ormachea J, Parker KJ, Johnson CL, Doyley MM. Reverberant magnetic resonance elastographic imaging using a single mechanical driver. Phys Med Biol 2023; 68:055015. [PMID: 36780698 PMCID: PMC9969521 DOI: 10.1088/1361-6560/acbbb7] [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] [Received: 05/16/2022] [Accepted: 02/13/2023] [Indexed: 02/15/2023]
Abstract
Reverberant elastography provides fast and robust estimates of shear modulus; however, its reliance on multiple mechanical drivers hampers clinical utility. In this work, we hypothesize that for constrained organs such as the brain, reverberant elastography can produce accurate magnetic resonance elastograms with a single mechanical driver. To corroborate this hypothesis, we performed studies on healthy volunteers (n= 3); and a constrained calibrated brain phantom containing spherical inclusions with diameters ranging from 4-18 mm. In both studies (i.e. phantom and clinical), imaging was performed at frequencies of 50 and 70 Hz. We used the accuracy and contrast-to-noise ratio performance metrics to evaluate reverberant elastograms relative to those computed using the established subzone inversion method. Errors incurred in reverberant elastograms varied from 1.3% to 16.6% when imaging at 50 Hz and 3.1% and 16.8% when imaging at 70 Hz. In contrast, errors incurred in subzone elastograms ranged from 1.9% to 13% at 50 Hz and 3.6% to 14.9% at 70 Hz. The contrast-to-noise ratio of reverberant elastograms ranged from 63.1 to 73 dB compared to 65 to 66.2 dB for subzone elastograms. The average global brain shear modulus estimated from reverberant and subzone elastograms was 2.36 ± 0.07 kPa and 2.38 ± 0.11 kPa, respectively, when imaging at 50 Hz and 2.70 ± 0.20 kPa and 2.89 ± 0.60 kPa respectively, when imaging at 70 Hz. The results of this investigation demonstrate that reverberant elastography can produce accurate, high-quality elastograms of the brain with a single mechanical driver.
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Affiliation(s)
- Irteza Enan Kabir
- University of Rochester, Hajim School of Engineering and Applied Sciences 1467, Rochester, NY, United States of America
| | - Diego A Caban-Rivera
- University of Delaware, Department of Biomedical Engineering 19716, Newark, DE, United States of America
| | - Juvenal Ormachea
- Verasonics, Inc., 11335 NE 122nd Way, Suite 100 98034 Kirkland, WA, United States of America
| | - Kevin J Parker
- University of Rochester, Hajim School of Engineering and Applied Sciences 1467, Rochester, NY, United States of America
| | - Curtis L Johnson
- University of Delaware, Department of Biomedical Engineering 19716, Newark, DE, United States of America
| | - Marvin M Doyley
- University of Rochester, Hajim School of Engineering and Applied Sciences 1467, Rochester, NY, United States of America
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Mustafi SM, Yang HC, Harezlak J, Meier TB, Brett BL, Giza CC, Goldman J, Guskiewicz KM, Mihalik JP, LaConte SM, Duma SM, Broglio SP, McCrea MA, McAllister TW, Wu YC. Effects of White-Matter Tract Length in Sport-Related Concussion: A Tractography Study from the NCAA-DoD CARE Consortium. J Neurotrauma 2022; 39:1495-1506. [PMID: 35730116 PMCID: PMC9689766 DOI: 10.1089/neu.2021.0239] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sport-related concussion (SRC) is an important public health issue. White-matter alterations after SRC are widely studied by neuroimaging approaches, such as diffusion magnetic resonance imaging (MRI). Although the exact anatomical location of the alterations may differ, significant white-matter alterations are commonly observed in long fiber tracts, but are never proven. In the present study, we performed streamline tractography to characterize the association between tract length and white-matter microstructural alterations after SRC. Sixty-eight collegiate athletes diagnosed with acute concussion (24-48 h post-injury) and 64 matched contact-sport controls were included in this study. The athletes underwent diffusion tensor imaging (DTI) in 3.0 T MRI scanners across three study sites. DTI metrics were used for tract-based spatial statistics to map white-matter regions-of-interest (ROIs) with significant group differences. Whole-brain white-mater streamline tractography was performed to extract "affected" white-matter streamlines (i.e., streamlines passing through the identified ROIs). In the concussed athletes, streamline counts and DTI metrics of the affected white-matter fiber tracts were summarized and compared with unaffected white-matter tracts across tract length in the same participant. The affected white-matter tracts had a high streamline count at length of 80-100 mm and high length-adjusted affected ratio for streamline length longer than 80 mm. DTI mean diffusivity was higher in the affected streamlines longer than 100 mm with significant associations with the Brief Symptom Inventory score. Our findings suggest that long fibers in the brains of collegiate athletes are more vulnerable to acute SRC with higher mean diffusivity and a higher affected ratio compared with the whole distribution.
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Affiliation(s)
- Sourajit M. Mustafi
- Institute of Genetics, San Diego, California, USA
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ho-Ching Yang
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Jaroslaw Harezlak
- Department of Epidemiology and Biostatistics, School of Public Health, Indiana University, Bloomington, Indiana, USA
| | - Timothy B. Meier
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Benjamin L. Brett
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Christopher C. Giza
- Department of Neurosurgery, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, USA
- Division of Pediatric Neurology, Mattel Children's Hospital, University of California, Los Angeles, Los Angeles, California, USA
| | - Joshua Goldman
- Family Medicine, Ronald Reagan UCLA Medical Center, UCLA Health - Santa Monica Medical Center, Los Angeles, California, USA
| | - Kevin M. Guskiewicz
- Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina, at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jason P. Mihalik
- Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina, at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Stephen M. LaConte
- School of Biomedical Engineering and Sciences, Wake-Forest and Virginia Tech University, Blacksburg, Virginia, USA
- Virginia Tech Carilion Research Institute, Roanoke, Virginia, USA
| | - Stefan M. Duma
- School of Biomedical Engineering and Sciences, Wake-Forest and Virginia Tech University, Blacksburg, Virginia, USA
| | - Steven P. Broglio
- Michigan Concussion Center, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Michael A. McCrea
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Thomas W. McAllister
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Yu-Chien Wu
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, USA
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10
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Tardieu M, Salameh N, Souris L, Rousseau D, Jourdain L, Skeif H, Prévot F, de Rochefort L, Ducreux D, Louis B, Garteiser P, Sinkus R, Darrasse L, Poirier-Quinot M, Maître X. Magnetic resonance elastography with guided pressure waves. NMR IN BIOMEDICINE 2022; 35:e4701. [PMID: 35088465 DOI: 10.1002/nbm.4701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.
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Affiliation(s)
- Marion Tardieu
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
- Montpellier Cancer Research Institute (IRCM), Inserm U1194, University of Montpellier, Montpellier, France
| | - Najat Salameh
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
- Center for Adaptable MRI Technology, Department of Biomedical Engineering, University of Basel, Allschwil, Switzerland
| | - Line Souris
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
| | | | - Laurène Jourdain
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
| | - Hanadi Skeif
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
| | - François Prévot
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
| | - Ludovic de Rochefort
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
- Aix-Marseille Université, CNRS, CRMBM, Marseille, France
- AP-HM, CHU Timone, Pôle d'Imagerie Médicale, CEMEREM, Marseille, France
| | - Denis Ducreux
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
| | - Bruno Louis
- Inserm-UPEC UMR955, CNRS EMR7000, Equipe Biomécanique Cellulaire et Respiratoire, Créteil, France
| | - Philippe Garteiser
- Laboratory of Imaging Biomarkers, Center for Research on Inflammation, UMR 1149, Inserm, Université de Paris, Paris, France
| | - Ralph Sinkus
- Imaging Sciences & Biomedical Engineering Division, King's College, London, United Kingdom
| | - Luc Darrasse
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
| | | | - Xavier Maître
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France
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11
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Hiscox LV, McGarry MDJ, Johnson CL. Evaluation of cerebral cortex viscoelastic property estimation with nonlinear inversion magnetic resonance elastography. Phys Med Biol 2022; 67. [PMID: 35316794 PMCID: PMC9208651 DOI: 10.1088/1361-6560/ac5fde] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 03/22/2022] [Indexed: 12/25/2022]
Abstract
Objective. Magnetic resonance elastography (MRE) of the brain has shown promise as a sensitive neuroimaging biomarker for neurodegenerative disorders; however, the accuracy of performing MRE of the cerebral cortex warrants investigation due to the unique challenges of studying thinner and more complex geometries.Approach. A series of realistic, whole-brain simulation experiments are performed to examine the accuracy of MRE to measure the viscoelasticity (shear stiffness,μ, and damping ratio, ξ) of cortical structures predominantly effected in aging and neurodegeneration. Variations to MRE spatial resolution and the regularization of a nonlinear inversion (NLI) approach are examined.Main results. Higher-resolution MRE displacement data (1.25 mm isotropic resolution) and NLI with a low soft prior regularization weighting provided minimal measurement error compared to other studied protocols. With the optimized protocol, an average error inμand ξ was 3% and 11%, respectively, when compared with the known ground truth. Mid-line structures, as opposed to those on the cortical surface, generally display greater error. Varying model boundary conditions and reducing the thickness of the cortex by up to 0.67 mm (which is a realistic portrayal of neurodegenerative pathology) results in no loss in reconstruction accuracy.Significance. These experiments establish quantitative guidelines for the accuracy expected ofin vivoMRE of the cortex, with the proposed method providing valid MRE measures for future investigations into cortical viscoelasticity and relationships with health, cognition, and behavior.
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Affiliation(s)
- Lucy V Hiscox
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States of America.,Department of Psychology, University of Bath, Bath, United Kingdom
| | - Matthew D J McGarry
- Thayer School of Engineering, Dartmouth College, Hanover, NH, United States of America
| | - Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States of America
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12
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Aunan-Diop JS, Pedersen CB, Halle B, Jensen U, Munthe S, Harbo F, Johannsson B, Poulsen FR. Magnetic resonance elastography in normal pressure hydrocephalus-a scoping review. Neurosurg Rev 2022; 45:1157-1169. [PMID: 34687356 DOI: 10.1007/s10143-021-01669-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/05/2021] [Accepted: 10/04/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND Magnetic resonance elastography (MRE) of the brain allows quantitative measurement of tissue mechanics. Multiple studies are exploring possible applications in normal pressure hydrocephalus (NPH) in clinical and paraclinical contexts. This is of great interest in neurological surgery due to challenges related to diagnosis and prediction of treatment effects. In this scoping review, we present a topical overview and discuss the current literature, with particular attention to clinical implications and current challenges. METHODS The protocol was based on the PRISMA extension for scoping reviews. After a systematic database search (PubMed, Embase, and Web of Science), the articles were screened for relevance. Thirty articles were subject to detailed screening, and key technical and clinical data items were extracted. The inclusion criteria included the use of MRE on human subjects with NPH. RESULTS Seven articles were included in the final study. These studies had various objectives including the role of MRE in the assessment of regional elastic changes in NPH, shunt effect, and evaluation of NPH symptoms. MRE revealed patterns of mechanical changes in NPH that differed from other dementias. Regional MRE changes were associated with specific NPH signs and symptoms. Neurosurgical shunting caused partial normalization in tissue scaffold parameters. The studies were highly heterogeneous in technical aspects and design. CONCLUSION MRE studies in NPH are still limited by few participants, variable cohorts, inconsistent methodologies, and technical challenges, but the approach shows great potential for future clinical application.
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Affiliation(s)
- Jan Saip Aunan-Diop
- Department of Neurosurgery, Odense University Hospital, Kløvervænget 47, Entrance 44, 5000, Odense C, Denmark. .,University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
| | - Christian Bonde Pedersen
- Department of Neurosurgery, Odense University Hospital, Kløvervænget 47, Entrance 44, 5000, Odense C, Denmark
| | - Bo Halle
- Department of Neurosurgery, Odense University Hospital, Kløvervænget 47, Entrance 44, 5000, Odense C, Denmark
| | - Ulla Jensen
- Department of Radiology, Odense University Hospital, Kløvervænget 47, Entrance 27, 5000, Odense C, Denmark
| | - Sune Munthe
- Department of Neurosurgery, Odense University Hospital, Kløvervænget 47, Entrance 44, 5000, Odense C, Denmark
| | - Fredrik Harbo
- Department of Radiology, Odense University Hospital, Kløvervænget 47, Entrance 27, 5000, Odense C, Denmark
| | - Bjarni Johannsson
- Department of Neurosurgery, Odense University Hospital, Kløvervænget 47, Entrance 44, 5000, Odense C, Denmark
| | - Frantz Rom Poulsen
- Department of Neurosurgery, Odense University Hospital, Kløvervænget 47, Entrance 44, 5000, Odense C, Denmark.,University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
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13
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Shi Y, Huo Y, Pan C, Qi Y, Yin Z, Ehman RL, Li Z, Yin X, Du B, Qi Z, Yang A, Hong Y. Use of magnetic resonance elastography to gauge meningioma intratumoral consistency and histotype. Neuroimage Clin 2022; 36:103173. [PMID: 36081257 PMCID: PMC9463601 DOI: 10.1016/j.nicl.2022.103173] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/24/2022] [Accepted: 08/25/2022] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To determine whether tumor shear stiffness, as measured by magnetic resonance elastography, corresponds with intratumoral consistency and histotype. MATERIALS AND METHODS A total of 88 patients with 89 meningiomas (grade 1, 74 typical [13 fibroblastic, 61 non-fibroblastic]; grade 2, 12 atypical; grade 3, 3 anaplastic) were prospectively studied, each undergoing preoperative MRE in conjunction with T1-, T2- and diffusion-weighted imaging. Contrast-enhanced T1-weighted sequences were also obtained. Tumor consistency was evaluated as heterogeneous or homogenous, and graded on a 5-point scale intraoperatively. MRE-determined shear stiffness was associated with tumor consistency by surgeon's evaluation and whole-slide histologic analyses. RESULTS Mean tumor stiffness overall was 3.81+/-1.74 kPa (range, 1.57-12.60 kPa), correlating well with intraoperative scoring (r = 0.748; p = 0.001). MRE performed well as a gauge of tumor consistency (AUC = 0.879, 95 % CI: 0.792-0.938) and heterogeneity (AUC = 0.773, 95 % CI: 0.618-0.813), significantly surpassing conventional MR techniques (DeLong test, all p < 0.001 after Bonferroni adjustment). Shear stiffness was independently correlated with both fibrous content (partial correlation coefficient = 0.752; p < 0.001) and tumor cellularity (partial correlation coefficient = 0.547; p < 0.001). MRE outperformed other imaging techniques in distinguishing fibroblastic meningiomas from other histotypes (AUC = 0.835 vs 0.513 ∼ 0.634; all p < 0.05), but showed limited ability to differentiate atypical or anaplastic meningiomas from typical meningiomas (AUC = 0.723 vs 0.616 ∼ 0.775; all p > 0.05). Small (<2.5 cm, n = 6) and intraventricular (n = 2) tumors displayed inconsistencies between MRE and surgeon's evaluation. CONCLUSIONS The results of this prospective study provide substantial evidence that preoperative evaluation of meningiomas with MRE can reliably characterize tumor stiffness and spatial heterogeneity to aid neurosurgical planning.
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Affiliation(s)
- Yu Shi
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Yunlong Huo
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Chen Pan
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Yafei Qi
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Ziying Yin
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN, United States
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN, United States
| | - Zhenyu Li
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Xiaoli Yin
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Bai Du
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Ziyang Qi
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, PR China
| | - Aoran Yang
- Department of Neurosurgery, Shengjing Hospital, China Medical University, Shenyang, PR China.
| | - Yang Hong
- Department of Neurosurgery, Shengjing Hospital, China Medical University, Shenyang, PR China.
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14
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Qiu S, He Z, Wang R, Li R, Zhang A, Yan F, Feng Y. An electromagnetic actuator for brain magnetic resonance elastography with high frequency accuracy. NMR IN BIOMEDICINE 2021; 34:e4592. [PMID: 34291510 DOI: 10.1002/nbm.4592] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 06/07/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
Our goal is to design, test and verify an electromagnetic actuator for brain magnetic resonance elastography (MRE). We proposed a grappler-shaped design that can transmit stable vibrations into the brain. To validate its performance, simulations were carried out to ensure the electromagnetic field generated by the actuator did not interfere with the B0 field. The actuation vibration spectrum was analyzed to verify the actuation accuracy. Phantom and volunteer experiments were carried out to evaluate the performance of the actuator. Simulation of the magnetic field showed that the proposed actuator has a fringe field of less than 3 G in the imaging region. The phantom experiments showed that the proposed actuator did not interfere with the routine imaging sequences. The measured vibration spectra demonstrated that the frequency offset was about one third that of a pneumatic device and the transmission efficiency was three times higher. The shear moduli estimated from brain MRE were consistent with those from the literature. The actuation frequency of the proposed actuator has less frequency offset and off-center frequency components compared with the pneumatic counterpart. The whole actuator weighted only 980 g. The actuator can carry out multifrequency MRE on the brain with high accuracy. It is easy to use, comfortable for the patient and portable.
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Affiliation(s)
- Suhao Qiu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zhao He
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Runke Wang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Ruokun Li
- Department of Radiology, Ruijin Hospital, Shanghai, China
| | - Aili Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Fuhua Yan
- Department of Radiology, Ruijin Hospital, Shanghai, China
| | - Yuan Feng
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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15
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Li W, Shepherd DET, Espino DM. Investigation of the Compressive Viscoelastic Properties of Brain Tissue Under Time and Frequency Dependent Loading Conditions. Ann Biomed Eng 2021; 49:3737-3747. [PMID: 34608583 PMCID: PMC8671270 DOI: 10.1007/s10439-021-02866-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 09/09/2021] [Indexed: 10/25/2022]
Abstract
The mechanical characterization of brain tissue has been generally analyzed in the frequency and time domain. It is crucial to understand the mechanics of the brain under realistic, dynamic conditions and convert it to enable mathematical modelling in a time domain. In this study, the compressive viscoelastic properties of brain tissue were investigated under time and frequency domains with the same physical conditions and the theory of viscoelasticity was applied to estimate the prediction of viscoelastic response in the time domain based on frequency-dependent mechanical moduli through Finite Element models. Storage and loss modulus were obtained from white and grey matter, of bovine brains, using dynamic mechanical analysis and time domain material functions were derived based on a Prony series representation. The material models were evaluated using brain testing data from stress relaxation and hysteresis in the time dependent analysis. The Finite Element models were able to represent the trend of viscoelastic characterization of brain tissue under both testing domains. The outcomes of this study contribute to a better understanding of brain tissue mechanical behaviour and demonstrate the feasibility of deriving time-domain viscoelastic parameters from frequency-dependent compressive data for biological tissue, as validated by comparing experimental tests with computational simulations.
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Affiliation(s)
- Weiqi Li
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Duncan E T Shepherd
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
| | - Daniel M Espino
- Department of Mechanical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
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16
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Bayly PV, Alshareef A, Knutsen AK, Upadhyay K, Okamoto RJ, Carass A, Butman JA, Pham DL, Prince JL, Ramesh KT, Johnson CL. MR Imaging of Human Brain Mechanics In Vivo: New Measurements to Facilitate the Development of Computational Models of Brain Injury. Ann Biomed Eng 2021; 49:2677-2692. [PMID: 34212235 PMCID: PMC8516723 DOI: 10.1007/s10439-021-02820-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/22/2021] [Indexed: 01/04/2023]
Abstract
Computational models of the brain and its biomechanical response to skull accelerations are important tools for understanding and predicting traumatic brain injuries (TBIs). However, most models have been developed using experimental data collected on animal models and cadaveric specimens, both of which differ from the living human brain. Here we describe efforts to noninvasively measure the biomechanical response of the human brain with MRI-at non-injurious strain levels-and generate data that can be used to develop, calibrate, and evaluate computational brain biomechanics models. Specifically, this paper reports on a project supported by the National Institute of Neurological Disorders and Stroke to comprehensively image brain anatomy and geometry, mechanical properties, and brain deformations that arise from impulsive and harmonic skull loadings. The outcome of this work will be a publicly available dataset ( http://www.nitrc.org/projects/bbir ) that includes measurements on both males and females across an age range from adolescence to older adulthood. This article describes the rationale and approach for this study, the data available, and how these data may be used to develop new computational models and augment existing approaches; it will serve as a reference to researchers interested in using these data.
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Affiliation(s)
- Philip V Bayly
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA.
| | - Ahmed Alshareef
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Andrew K Knutsen
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Kshitiz Upadhyay
- Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Ruth J Okamoto
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Aaron Carass
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - John A Butman
- Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Dzung L Pham
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Jerry L Prince
- Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - K T Ramesh
- Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, MD, USA
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA.
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17
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Ozkaya E, Triolo ER, Rezayaraghi F, Abderezaei J, Meinhold W, Hong K, Alipour A, Kennedy P, Fleysher L, Ueda J, Balchandani P, Eriten M, Johnson CL, Yang Y, Kurt M. Brain-mimicking phantom for biomechanical validation of motion sensitive MR imaging techniques. J Mech Behav Biomed Mater 2021; 122:104680. [PMID: 34271404 DOI: 10.1016/j.jmbbm.2021.104680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/07/2021] [Accepted: 06/30/2021] [Indexed: 10/20/2022]
Abstract
Motion sensitive MR imaging techniques allow for the non-invasive evaluation of biological tissues by using different excitation schemes, including physiological/intrinsic motions caused by cardiac pulsation or respiration, and vibrations caused by an external actuator. The mechanical biomarkers extracted through these imaging techniques have been shown to hold diagnostic value for various neurological disorders and conditions. Amplified MRI (aMRI), a cardiac gated imaging technique, can help track and quantify low frequency intrinsic motion of the brain. As for high frequency actuation, the mechanical response of brain tissue can be measured by applying external high frequency actuation in combination with a motion sensitive MR imaging sequence called Magnetic Resonance Elastography (MRE). Due to the frequency-dependent behavior of brain mechanics, there is a need to develop brain phantom models that can mimic the broadband mechanical response of the brain in order to validate motion-sensitive MR imaging techniques. Here, we have designed a novel phantom test setup that enables both the low and high frequency responses of a brain-mimicking phantom to be captured, allowing for both aMRI and MRE imaging techniques to be applied on the same phantom model. This setup combines two different vibration sources: a pneumatic actuator, for low frequency/intrinsic motion (1 Hz) for use in aMRI, and a piezoelectric actuator for high frequency actuation (30-60 Hz) for use in MRE. Our results show that in MRE experiments performed from 30 Hz through 60 Hz, propagating shear waves attenuate faster at higher driving frequencies, consistent with results in the literature. Furthermore, actuator coupling has a substantial effect on wave amplitude, with weaker coupling causing lower amplitude wave field images, specifically shown in the top-surface shear loading configuration. For intrinsic actuation, our results indicate that aMRI linearly amplifies motion up to at least an amplification factor of 9 for instances of both visible and sub-voxel motion, validated by varying power levels of pneumatic actuation (40%-80% power) under MR, and through video analysis outside the MRI scanner room. While this investigation used a homogeneous brain-mimicking phantom, our setup can be used to study the mechanics of non-homogeneous phantom configurations with bio-interfaces in the future.
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Affiliation(s)
- E Ozkaya
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA.
| | - E R Triolo
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - F Rezayaraghi
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - J Abderezaei
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - W Meinhold
- The George W. Woodruff of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - K Hong
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - A Alipour
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - P Kennedy
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - L Fleysher
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - J Ueda
- The George W. Woodruff of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - P Balchandani
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - M Eriten
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - C L Johnson
- Department of Biomedical Engineering, University of Deleware, Newark, DE, 19716, USA
| | - Y Yang
- BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - M Kurt
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA; BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
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18
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Escarcega JD, Knutsen AK, Okamoto RJ, Pham DL, Bayly PV. Natural oscillatory modes of 3D deformation of the human brain in vivo. J Biomech 2021; 119:110259. [PMID: 33618329 PMCID: PMC8055167 DOI: 10.1016/j.jbiomech.2021.110259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 01/04/2021] [Accepted: 01/10/2021] [Indexed: 12/12/2022]
Abstract
Natural modes and frequencies of three-dimensional (3D) deformation of the human brain were identified from in vivo tagged magnetic resonance images (MRI) acquired dynamically during transient mild acceleration of the head. Twenty 3D strain fields, estimated from tagged MRI image volumes in 19 adult subjects, were analyzed using dynamic mode decomposition (DMD). These strain fields represented dynamic, 3D brain deformations during constrained head accelerations, either involving rotation about the vertical axis of the neck or neck extension. DMD results reveal fundamental oscillatory modes of deformation at damped frequencies near 7 Hz (in neck rotation) and 11 Hz (in neck extension). Modes at these frequencies were found consistently among all subjects. These characteristic features of 3D human brain deformation are important for understanding the response of the brain in head impacts and provide valuable quantitative criteria for the evaluation and use of computer models of brain mechanics.
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Affiliation(s)
- J D Escarcega
- Mechanical Engineering and Materials Science, Washington University in St. Louis, MO, United States.
| | - A K Knutsen
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - R J Okamoto
- Mechanical Engineering and Materials Science, Washington University in St. Louis, MO, United States
| | - D L Pham
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - P V Bayly
- Mechanical Engineering and Materials Science, Washington University in St. Louis, MO, United States
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19
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Simulation of harmonic shear waves in the human brain and comparison with measurements from magnetic resonance elastography. J Mech Behav Biomed Mater 2021; 118:104449. [PMID: 33770585 DOI: 10.1016/j.jmbbm.2021.104449] [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: 08/10/2020] [Revised: 02/07/2021] [Accepted: 03/04/2021] [Indexed: 11/21/2022]
Abstract
Magnetic Resonance Elastography (MRE) provides a non-invasive method to characterize the mechanical response of the living brain subjected to harmonic loading conditions. The peak magnitude of the harmonic strain is small and the excitation results in harmless deformation waves propagating through the brain. In this paper, we describe a three-dimensional computational model of the brain for comparison of simulated harmonic deformations of the brain with MRE measurements. Relevant substructures of the head were constructed from MRI scans. Harmonic wave motions in a live human brain obtained in an MRE experiment were used to calibrate the viscoelastic properties at 50 Hz and assess accuracy of the computational model by comparing the measured and the simulated harmonic response of the brain. Quantitative comparison of strain field from simulations with measured data from MRE shows that the harmonic deformation of the brain tissue is responsive to changes in the viscoelastic properties, loss and storage moduli, of the brain. The simulation results demonstrate, in agreement with MRE measurements, that the presence of the falx and tentorium membranes alter the spatial distribution of harmonic deformation field and peak strain amplitudes in the computational model of the brain.
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20
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Arani A, Manduca A, Ehman RL, Huston Iii J. Harnessing brain waves: a review of brain magnetic resonance elastography for clinicians and scientists entering the field. Br J Radiol 2021; 94:20200265. [PMID: 33605783 PMCID: PMC8011257 DOI: 10.1259/bjr.20200265] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Brain magnetic resonance elastography (MRE) is an imaging technique capable of accurately and non-invasively measuring the mechanical properties of the living human brain. Recent studies have shown that MRE has potential to provide clinically useful information in patients with intracranial tumors, demyelinating disease, neurodegenerative disease, elevated intracranial pressure, and altered functional states. The objectives of this review are: (1) to give a general overview of the types of measurements that have been obtained with brain MRE in patient populations, (2) to survey the tools currently being used to make these measurements possible, and (3) to highlight brain MRE-based quantitative biomarkers that have the highest potential of being adopted into clinical use within the next 5 to 10 years. The specifics of MRE methodology strategies are described, from wave generation to material parameter estimations. The potential clinical role of MRE for characterizing and planning surgical resection of intracranial tumors and assessing diffuse changes in brain stiffness resulting from diffuse neurological diseases and altered intracranial pressure are described. In addition, the emerging technique of functional MRE, the role of artificial intelligence in MRE, and promising applications of MRE in general neuroscience research are presented.
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Affiliation(s)
- Arvin Arani
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Armando Manduca
- Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
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21
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Tripathi BB, Chandrasekaran S, Pinton GF. Super-resolved shear shock focusing in the human head. BRAIN MULTIPHYSICS 2021. [DOI: 10.1016/j.brain.2021.100033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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22
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Dynamic mechanical characterization and viscoelastic modeling of bovine brain tissue. J Mech Behav Biomed Mater 2020; 114:104204. [PMID: 33218929 DOI: 10.1016/j.jmbbm.2020.104204] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 10/23/2020] [Accepted: 11/07/2020] [Indexed: 01/12/2023]
Abstract
Brain tissue is vulnerable and sensitive, predisposed to potential damage under various conditions of mechanical loading. Although its material properties have been investigated extensively, the frequency-dependent viscoelastic characterization is currently limited. Computational models can provide a non-invasive method by which to analyze brain injuries and predict the mechanical response of the tissue. The brain injuries are expected to be induced by dynamic loading, mostly in compression and measurement of dynamic viscoelastic properties are essential to improve the accuracy and variety of finite element simulations on brain tissue. Thus, the aim of this study was to investigate the compressive frequency-dependent properties of brain tissue and present a mathematical model in the frequency domain to capture the tissue behavior based on experimental results. Bovine brain specimens, obtained from four locations of corona radiata, corpus callosum, basal ganglia and cortex, were tested under compression using dynamic mechanical analysis over a range of frequencies between 0.5 and 35 Hz to characterize the regional and directional response of the tissue. The compressive dynamic properties of bovine brain tissue were heterogenous for regions but not sensitive to orientation showing frequency dependent statistical results, with viscoelastic properties increasing with frequency. The mean storage and loss modulus were found to be 12.41 kPa and 5.54 kPa, respectively. The material parameters were obtained using the linear viscoelastic model in the frequency domain and the numeric simulation can capture the compressive mechanical behavior of bovine brain tissue across a range of frequencies. The frequency-dependent viscoelastic characterization of brain tissue will improve the fidelity of the computational models of the head and provide essential information to the prediction and analysis of brain injuries in clinical treatments.
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23
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Hu L, Shan X. Enhanced complex local frequency elastography method for tumor viscoelastic shear modulus reconstruction. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 195:105605. [PMID: 32580075 DOI: 10.1016/j.cmpb.2020.105605] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 06/07/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVES The Mayo Clinic provides a magnetic resonance (MR) elastography software named MRE Wave, which uses the conventional local frequency elastography (LFE) method. However, MRE Wave is unable to supply complex viscoelasticity maps for elastography. We sought to improve the local frequency estimation algorithm used in LFE, which we refer to as the Enhanced Complex Local Frequency Elastography (EC-LFE) algorithm. METHODS The proposed algorithm uses wave equations under the hypotheses of being linear, isotropic, and locally homogeneous. Two 2D simulation models were used to investigate the accuracy and sensitivity of the EC-LFE algorithm for detecting small tumors. The corresponding statistical parameters were the relative root mean square (RMS) error and contrast-to-noise ratio (CNR). EC-LFE was investigated with two different parameter sets, one with an optimally chosen parameter ξ (EC-LFE Adj, for short) and the other with ξ = 0 (EC-LFE0). We compared the MRE Wave and the EC-LFE using series signal-to-noise (SNR) wave data. RESULTS The elasticity RMS error of the MRE Wave software was about 1%, and that of the EC-LFE0 and EC-LFE Adj were about 0.2%. The elasticity standard deviation of the MRE Wave software was about 3% of the mean value, and those of the EC-LFE0 and EC-LFE Adj were about 1% of the mean value. The elasticity CNR value of EC-LFE0 reached 1.93 times that of the MRE Wave in the region of small tumors (less than 10-point sampling). The viscosity RMS errors of the EC-LFE0 could be less than 5%. CONCLUSION Compared to conventional methods, the EC-LFE was more accurate and sensitive for small tumor detection and exhibited higher noise immunity. The improved algorithm output more parameters and outperformed than the MRE Wave, thereby rendering them more suitable for clinical applications.
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Affiliation(s)
- Liangliang Hu
- School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Hefei, Anhui, China.
| | - Xiang Shan
- School of Medical Imaging, Xuzhou Medical University, Xuzhou, Jiangsu, China
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Hu L. Requirements for accurate estimation of shear modulus by magnetic resonance elastography: A computational comparative study. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2020; 192:105437. [PMID: 32182441 DOI: 10.1016/j.cmpb.2020.105437] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 03/01/2020] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Magnetic resonance (MR) elastography is a non-destructive method of measuring biological tissue and is conducive to the early detection of tumors. Researchers usually set different assumptions according to different research objects, then establish and solve wave equations to estimate the shear modulus. Establishing a more reasonable model for a measured object estimates a more accurate shear modulus. Different assumptions of the mathematical model, and the method used to solve the wave equation causes deviation of the estimation. OBJECTIVE This study focused on shear modulus deviations caused by differences in calculation methods. The author demonstrated a method to ensure that the measuring range of the selected reconstruction algorithm with selected drive frequency covers the elasticity range of the target tissue. It is hoped to arouse the interest of researchers to introduce new transform domain methods to the field of MR elastography. METHOD In linear, isotropic and local homogeneity assumptions, the typical representative of two different calculation methods are algebraic inversion of the differential equation (AIDE) algorithm and local frequency elastography (LFE) algorithm. To compare the accuracy of these calculation methods, the author adopted a digital phantom that can set the parameter values accurately. It is assumed that the phantom tissue was linear and isotropic, and that the driving wave was sinusoidal. The displacement distribution of waves in the tissue was calculated by the finite element simulation method in two different resolutions with the signal-to-noise ratio (SNR) set to 40 dB and the threshold of relative mean error (RME) no more than 10%. The wavelength-to-pixel-size ratios of the two methods under the setting threshold of RME were compared. RESULTS The lower threshold of wavelength-to-pixel-size ratio for AIDE was close to 10, while that for LFE was nearly 2 (the limitation of Shannon's law) under the setting precision. Thus, the measuring range of the AIDE method was less than that of LFE at the same experimental conditions. CONCLUSION The driving frequency selection range of the spatial frequency domain method is wider than that of the spatial domain method. It is worthwhile for researchers to devote more time to introducing new transformation domain method for MR elastography.
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Affiliation(s)
- Liangliang Hu
- School of Instrument Science and Opto-electronics Engineering, Hefei University of Technology, Tunxi Road 193, Hefei, China.
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25
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Rouleau N, Murugan NJ, Rusk W, Koester C, Kaplan DL. Matrix Deformation with Ectopic Cells Induced by Rotational Motion in Bioengineered Neural Tissues. Ann Biomed Eng 2020; 48:2192-2203. [PMID: 32671625 PMCID: PMC7405955 DOI: 10.1007/s10439-020-02561-6] [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: 03/21/2020] [Accepted: 06/29/2020] [Indexed: 11/30/2022]
Abstract
The brain's extracellular matrix (ECM) is a dynamic protein-based scaffold within which neural networks can form, self-maintain, and re-model. When the brain incurs injuries, microscopic tissue tears and active ECM re-modelling give way to abnormal brain structure and function including the presence of ectopic cells. Post-mortem and neuroimaging data suggest that the brains of jet pilots and astronauts, who are exposed to rotational forces, accelerations, and microgravity, display brain anomalies which could be indicative of a mechanodisruptive pathology. Here we present a model of non-impact-based brain injury induced by matrix deformation following mechanical shaking. Using a bioengineered 3D neural tissue platform, we designed a repetitive shaking paradigm to simulate subtle rotational acceleration. Our results indicate shaking induced ectopic cell clustering that could be inhibited by physically restraining tissue movement. Imaging revealed that the collagen substrate surrounding cells was deformed following shaking. Applied to neonatal rat brains, shaking induced deformation of extracellular spaces within the cerebral cortices and reduced the number of cell bodies at higher accelerations. We hypothesize that ECM deformation may represent a more significant role in brain injury progression than previously assumed and that the present model system contributes to its understanding as a phenomenon.
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Affiliation(s)
- Nicolas Rouleau
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, MA, USA
- Initiative for Neural Science, Disease, and Engineering (INSciDE), Tufts University, Medford, USA
- The Allen Discovery Center, Tufts University, Medford, USA
| | - Nirosha J Murugan
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, MA, USA
- The Allen Discovery Center, Tufts University, Medford, USA
- Department of Biology, Tufts University, Medford, USA
| | - William Rusk
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, MA, USA
| | - Cole Koester
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, MA, USA
| | - David L Kaplan
- Department of Biomedical Engineering, Science & Technology Center, Tufts University, Medford, MA, USA.
- Initiative for Neural Science, Disease, and Engineering (INSciDE), Tufts University, Medford, USA.
- The Allen Discovery Center, Tufts University, Medford, USA.
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Salahshoor H, Shapiro MG, Ortiz M. Transcranial focused ultrasound generates skull-conducted shear waves: Computational model and implications for neuromodulation. APPLIED PHYSICS LETTERS 2020; 117:033702. [PMID: 32741976 PMCID: PMC7386437 DOI: 10.1063/5.0011837] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/22/2020] [Indexed: 05/12/2023]
Abstract
Focused ultrasound (FUS) is an established technique for non-invasive surgery and has recently attracted considerable attention as a potential method for non-invasive neuromodulation. While the pressure waves in FUS procedures have been extensively studied in this context, the accompanying shear waves are often neglected due to the relatively high shear compliance of soft tissues. However, in bony structures such as the skull, acoustic pressure can also induce significant shear waves that could propagate outside the ultrasound focus. Here, we investigate wave propagation in the human cranium by means of a finite-element model that accounts for the anatomy, elasticity, and viscoelasticity of the skull and brain. We show that, when a region on the scalp is subjected to FUS, the skull acts as a waveguide for shear waves that propagate with a speed close to 1500 m/s, reaching off-target structures such as the cochlea. In particular, when a sharp onset of FUS is introduced in a zone proximal to the intersection of the parietal and temporal cranium, the bone-propagated shear waves reach the inner ear in about 40 μ s , leading to cumulative displacements of about 1 μ m . We further quantify the effect of ramped and sharp application of FUS on the cumulative displacements in the inner ear. Our results help explain the off-target auditory responses observed during neuromodulation experiments and inform the development of mitigation and sham control strategies.
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Affiliation(s)
- Hossein Salahshoor
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
| | - Mikhail G. Shapiro
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Michael Ortiz
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
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27
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Smith DR, Guertler CA, Okamoto RJ, Romano AJ, Bayly PV, Johnson CL. Multi-Excitation Magnetic Resonance Elastography of the Brain: Wave Propagation in Anisotropic White Matter. J Biomech Eng 2020; 142:071005. [PMID: 32006012 PMCID: PMC7104761 DOI: 10.1115/1.4046199] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 01/21/2020] [Indexed: 12/13/2022]
Abstract
Magnetic resonance elastography (MRE) has emerged as a sensitive imaging technique capable of providing a quantitative understanding of neural microstructural integrity. However, a reliable method for the quantification of the anisotropic mechanical properties of human white matter is currently lacking, despite the potential to illuminate the pathophysiology behind neurological disorders and traumatic brain injury. In this study, we examine the use of multiple excitations in MRE to generate wave displacement data sufficient for anisotropic inversion in white matter. We show the presence of multiple unique waves from each excitation which we combine to solve for parameters of an incompressible, transversely isotropic (ITI) material: shear modulus, μ, shear anisotropy, ϕ, and tensile anisotropy, ζ. We calculate these anisotropic parameters in the corpus callosum body and find the mean values as μ = 3.78 kPa, ϕ = 0.151, and ζ = 0.099 (at 50 Hz vibration frequency). This study demonstrates that multi-excitation MRE provides displacement data sufficient for the evaluation of the anisotropic properties of white matter.
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Affiliation(s)
- Daniel R. Smith
- Department of Biomedical Engineering, University of
Delaware, Newark, DE 19716
| | - Charlotte A. Guertler
- Department of Mechanical Engineering and Material Science,
Washington University, St. Louis, MO
63130
| | - Ruth J. Okamoto
- Department of Mechanical Engineering and Material Science,
Washington University, St. Louis, MO
63130
| | | | - Philip V. Bayly
- Department of Mechanical Engineering and Material Science,
Washington University, St. Louis, MO
63130
| | - Curtis L. Johnson
- Department of Biomedical Engineering, University of
Delaware, Newark, DE 19716
e-mail:
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28
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Losurdo M, Davidsson J, Sköld MK. Diffuse Axonal Injury in the Rat Brain: Axonal Injury and Oligodendrocyte Activity Following Rotational Injury. Brain Sci 2020; 10:brainsci10040229. [PMID: 32290212 PMCID: PMC7225974 DOI: 10.3390/brainsci10040229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/03/2020] [Accepted: 04/07/2020] [Indexed: 02/06/2023] Open
Abstract
Traumatic brain injury (TBI) commonly results in primary diffuse axonal injury (DAI) and associated secondary injuries that evolve through a cascade of pathological mechanisms. We aim at assessing how myelin and oligodendrocytes react to head angular-acceleration-induced TBI in a previously described model. This model induces axonal injuries visible by amyloid precursor protein (APP) expression, predominantly in the corpus callosum and its borders. Brain tissue from a total of 27 adult rats was collected at 24 h, 72 h and 7 d post-injury. Coronal sections were prepared for immunohistochemistry and RNAscope® to investigate DAI and myelin changes (APP, MBP, Rip), oligodendrocyte lineage cell loss (Olig2), oligodendrocyte progenitor cells (OPCs) (NG2, PDGFRa) and neuronal stress (HSP70, ATF3). Oligodendrocytes and OPCs numbers (expressed as percentage of positive cells out of total number of cells) were measured in areas with high APP expression. Results showed non-statistically significant trends with a decrease in oligodendrocyte lineage cells and an increase in OPCs. Levels of myelination were mostly unaltered, although Rip expression differed significantly between sham and injured animals in the frontal brain. Neuronal stress markers were induced at the dorsal cortex and habenular nuclei. We conclude that rotational injury induces DAI and neuronal stress in specific areas. We noticed indications of oligodendrocyte death and regeneration without statistically significant changes at the timepoints measured, despite indications of axonal injuries and neuronal stress. This might suggest that oligodendrocytes are robust enough to withstand this kind of trauma, knowledge important for the understanding of thresholds for cell injury and post-traumatic recovery potential.
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Affiliation(s)
- Michela Losurdo
- Department of Neuroscience, Karolinska Institute, 171 77 Stockholm, Sweden;
- Department of Molecular Medicine, Università degli Studi di Pavia, 27100 Pavia, Italy
- Correspondence:
| | - Johan Davidsson
- Department of Mechanics and Maritime Sciences, Chalmers University of Technology, 412 96 Gothenburg, Sweden;
| | - Mattias K. Sköld
- Department of Neuroscience, Karolinska Institute, 171 77 Stockholm, Sweden;
- Department of Neuroscience, Section of Neurosurgery, Uppsala University, 751 85 Uppsala, Sweden
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29
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Chan DD, Knutsen AK, Lu YC, Yang SH, Magrath E, Wang WT, Bayly PV, Butman JA, Pham DL. Statistical Characterization of Human Brain Deformation During Mild Angular Acceleration Measured In Vivo by Tagged Magnetic Resonance Imaging. J Biomech Eng 2019; 140:2681445. [PMID: 30029236 DOI: 10.1115/1.4040230] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Indexed: 01/17/2023]
Abstract
Understanding of in vivo brain biomechanical behavior is critical in the study of traumatic brain injury (TBI) mechanisms and prevention. Using tagged magnetic resonance imaging, we measured spatiotemporal brain deformations in 34 healthy human volunteers under mild angular accelerations of the head. Two-dimensional (2D) Lagrangian strains were examined throughout the brain in each subject. Strain metrics peaked shortly after contact with a padded stop, corresponding to the inertial response of the brain after head deceleration. Maximum shear strain of at least 3% was experienced at peak deformation by an area fraction (median±standard error) of 23.5±1.8% of cortical gray matter, 15.9±1.4% of white matter, and 4.0±1.5% of deep gray matter. Cortical gray matter strains were greater in the temporal cortex on the side of the initial contact with the padded stop and also in the contralateral temporal, frontal, and parietal cortex. These tissue-level deformations from a population of healthy volunteers provide the first in vivo measurements of full-volume brain deformation in response to known kinematics. Although strains differed in different tissue type and cortical lobes, no significant differences between male and female head accelerations or strain metrics were found. These cumulative results highlight important kinematic features of the brain's mechanical response and can be used to facilitate the evaluation of computational simulations of TBI.
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Affiliation(s)
- Deva D Chan
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180
| | - Andrew K Knutsen
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20892
| | - Yuan-Chiao Lu
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20892
| | - Sarah H Yang
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20892
| | - Elizabeth Magrath
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20892
| | - Wen-Tung Wang
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20892
| | - Philip V Bayly
- Professor Department of Mechanical Engineering and Materials Science, Washington University at St. Louis, St. Louis, MO 63130
| | - John A Butman
- Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD 20892
| | - Dzung L Pham
- Center for Neuroscience and Regenerative Medicine, The Henry M. Jackson Foundation for the Advancement of Military Medicine, , Bethesda, MD 20892-1182 e-mail:
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30
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Okamoto RJ, Romano AJ, Johnson CL, Bayly PV. Insights Into Traumatic Brain Injury From MRI of Harmonic Brain Motion. J Exp Neurosci 2019; 13:1179069519840444. [PMID: 31001064 PMCID: PMC6454654 DOI: 10.1177/1179069519840444] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/07/2019] [Indexed: 12/14/2022] Open
Abstract
Measurements of dynamic deformation of the human brain, induced by external
harmonic vibration of the skull, were analyzed to illuminate the mechanics of
mild traumatic brain injury (TBI). Shear wave propagation velocity vector fields
were obtained to illustrate the role of the skull and stiff internal membranes
in transmitting motion to the brain. Relative motion between the cerebrum and
cerebellum was quantified to assess the vulnerability of connecting structures.
Mechanical deformation was quantified throughout the brain to investigate
spatial patterns of strain and axonal stretch. Strain magnitude was generally
attenuated as shear waves propagated into interior structures of the brain; this
attenuation was greater at higher frequencies. Analysis of shear wave
propagation direction indicates that the stiff membranes (falx and tentorium)
greatly affect brain deformation during imposed skull motion as they serve as
sites for both initiation and reflection of shear waves. Relative motion between
the cerebellum and cerebrum was small in comparison with the overall motion of
both structures, which suggests that such relative motion might play only a
minor role in TBI mechanics. Strain magnitudes and the amount of axonal stretch
near the bases of sulci were similar to those in other areas of the cortex, and
local strain concentrations at the gray-white matter boundary were not observed.
We tentatively conclude that observed differences in neuropathological response
in these areas might be due to heterogeneity in the response to mechanical
deformation rather than heterogeneity of the deformation itself.
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Affiliation(s)
- Ruth J Okamoto
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA
| | - Anthony J Romano
- Acoustics Division, U.S. Naval Research Laboratory, Washington, DC, USA
| | - Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, DE, USA
| | - Philip V Bayly
- Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, USA
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31
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Sharma AK, Reis J, Oppenheimer DC, Rubens DJ, Ormachea J, Hah Z, Parker KJ. Attenuation of Shear Waves in Normal and Steatotic Livers. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:895-901. [PMID: 30685077 DOI: 10.1016/j.ultrasmedbio.2018.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/29/2018] [Accepted: 12/08/2018] [Indexed: 06/09/2023]
Abstract
Shear wave propagation in the liver has been a robust subject of research, with shear wave speed receiving the most attention. The correlation between increased shear wave speed and increased fibrosis in the liver has been established as a useful diagnostic tool. In comparison, the precise mechanisms of shear wave attenuation, and its relation to diseased states of the liver, are less well-established. This study focused on the hypothesis that steatosis adds a viscous (lossy) component to the liver, which increases shear wave attenuation. Twenty patients' livers were scanned with ultrasound and with induced shear wave propagation, and the resulting displacement profiles were analyzed using recently developed estimators to derive both the speed and attenuation of the shear waves within 6-cm2 regions of interest. The results were compared with pathology scores obtained from liver biopsies taken under ultrasound guidance. Across these cases, increases in shear wave attenuation were linked to increased steatosis score. This preliminary study supports the hypothesis and indicates the possible utility of the measurements for non-invasive and quantitative assessment of steatosis.
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Affiliation(s)
- Ashwani K Sharma
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Joseph Reis
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Daniel C Oppenheimer
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Deborah J Rubens
- Department of Imaging Sciences, University of Rochester Medical Center, Rochester, New York, USA
| | - Juvenal Ormachea
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA
| | | | - Kevin J Parker
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA.
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Huang X, Chafi H, Matthews KL, Carmichael O, Li T, Miao Q, Wang S, Jia G. Magnetic resonance elastography of the brain: A study of feasibility and reproducibility using an ergonomic pillow-like passive driver. Magn Reson Imaging 2019; 59:68-76. [PMID: 30858002 DOI: 10.1016/j.mri.2019.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 03/08/2019] [Accepted: 03/08/2019] [Indexed: 01/12/2023]
Abstract
Magnetic resonance elastography (MRE) can be used to noninvasively resolve the displacement pattern of induced mechanical waves propagating in tissue. The goal of this study is to establish an ergonomically flexible passive-driver design for brain MRE, to evaluate the reproducibility of MRE tissue-stiffness measurements, and to investigate the relationship between tissue-stiffness measurements and driver frequencies. An ergonomically flexible passive pillow-like driver was designed to induce mechanical waves in the brain. Two-dimensional finite-element simulation was used to evaluate mechanical wave propagation patterns in brain tissues. MRE scans were performed on 10 healthy volunteers at mechanical frequencies of 60, 50, and 40 Hz. An axial mid-brain slice was acquired using an echo-planar imaging sequence to map the displacement pattern with the motion-encoding gradient along the through-plane (z) direction. All subjects were scanned and rescanned within 1 h. The Wilcoxon signed-rank test was used to test for differences between white matter and gray matter shear-stiffness values. One-way analysis of variance (ANOVA) was used to test for differences between shear-stiffness measurements made at different frequencies. Scan-rescan reproducibility was evaluated by calculating the within-subject coefficient of variation (CV) for each subject. The finite-element simulation showed that a pillow-like passive driver is capable of efficient shear-wave propagation through brain tissue. No subjects complained about discomfort during MRE acquisitions using the ergonomically designed driver. The white-matter elastic modulus (mean ± standard deviation) across all subjects was 3.85 ± 0.12 kPa, 3.78 ± 0.15 kPa, and 3.36 ± 0.11 kPa at frequencies of 60, 50, and 40 Hz, respectively. The gray-matter elastic modulus across all subjects was 3.33 ± 0.14 kPa, 2.82 ± 0.16 kPa, and 2.24 ± 0.14 kPa at frequencies of 60, 50, and 40 Hz, respectively. The Wilcoxon signed-rank test confirmed that the shear stiffness was significantly higher in white matter than gray matter at all three frequencies. The ranges of within-subject coefficients of variation for white matter, gray matter, and whole-brain shear-stiffness measurements for the three frequencies were 1.8-3.5% (60 Hz), 4.7-6.0% (50 Hz), and 3.7-4.1% (40 Hz). An ergonomic pneumatic pillow-like driver is feasible for highly reproducible in vivo evaluation of brain-tissue shear stiffness. Brain-tissue shear-stiffness values were frequency-dependent, thus emphasizing the importance of standardizing MRE acquisition protocols in multi-center studies.
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Affiliation(s)
- Xunan Huang
- School of Computer Science and Technology, Xidian University, Xi'an, Shaanxi, 710071, China
| | - Hatim Chafi
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Kenneth L Matthews
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Owen Carmichael
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Tanping Li
- School of Physics and Optoelectronic Engineering, Xidian University, Xi'an, Shaanxi 710071, China
| | - Qiguang Miao
- School of Computer Science and Technology, Xidian University, Xi'an, Shaanxi, 710071, China
| | - Shuzhen Wang
- School of Computer Science and Technology, Xidian University, Xi'an, Shaanxi, 710071, China.
| | - Guang Jia
- School of Computer Science and Technology, Xidian University, Xi'an, Shaanxi, 710071, China.
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Terem I, Ni WW, Goubran M, Rahimi MS, Zaharchuk G, Yeom KW, Moseley ME, Kurt M, Holdsworth SJ. Revealing sub-voxel motions of brain tissue using phase-based amplified MRI (aMRI). Magn Reson Med 2018; 80:2549-2559. [PMID: 29845645 PMCID: PMC6269230 DOI: 10.1002/mrm.27236] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 03/28/2018] [Accepted: 04/05/2018] [Indexed: 01/15/2023]
Abstract
PURPOSE Amplified magnetic resonance imaging (aMRI) was recently introduced as a new brain motion detection and visualization method. The original aMRI approach used a video-processing algorithm, Eulerian video magnification (EVM), to amplify cardio-ballistic motion in retrospectively cardiac-gated MRI data. Here, we strive to improve aMRI by incorporating a phase-based motion amplification algorithm. METHODS Phase-based aMRI was developed and tested for correct implementation and ability to amplify sub-voxel motions using digital phantom simulations. The image quality of phase-based aMRI was compared with EVM-based aMRI in healthy volunteers at 3T, and its amplified motion characteristics were compared with phase-contrast MRI. Data were also acquired on a patient with Chiari I malformation, and qualitative displacement maps were produced using free form deformation (FFD) of the aMRI output. RESULTS Phantom simulations showed that phase-based aMRI has a linear dependence of amplified displacement on true displacement. Amplification was independent of temporal frequency, varying phantom intensity, Rician noise, and partial volume effect. Phase-based aMRI supported larger amplification factors than EVM-based aMRI and was less sensitive to noise and artifacts. Abnormal biomechanics were seen on FFD maps of the Chiari I malformation patient. CONCLUSION Phase-based aMRI might be used in the future for quantitative analysis of minute changes in brain motion and may reveal subtle physiological variations of the brain as a result of pathology using processing of the fundamental harmonic or by selectively varying temporal harmonics. Preliminary data shows the potential of phase-based aMRI to qualitatively assess abnormal biomechanics in Chiari I malformation.
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Affiliation(s)
- Itamar Terem
- Department of Radiology, Stanford University, Stanford, California
| | - Wendy W Ni
- Department of Radiology, Stanford University, Stanford, California
| | - Maged Goubran
- Department of Radiology, Stanford University, Stanford, California
| | | | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, California
| | - Kristen W Yeom
- Department of Radiology, Stanford University, Stanford, California
| | | | - Mehmet Kurt
- Stevens Institute of Technology, Hoboken, New Jersey
| | - Samantha J Holdsworth
- Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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34
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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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Feng Y, Zhu M, Qiu S, Shen P, Ma S, Zhao X, Hu CH, Guo L. A multi-purpose electromagnetic actuator for magnetic resonance elastography. Magn Reson Imaging 2018; 51:29-34. [DOI: 10.1016/j.mri.2018.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 04/15/2018] [Indexed: 01/17/2023]
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36
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Yin Z, Sui Y, Trzasko JD, Rossman PJ, Manduca A, Ehman RL, Huston J. In vivo characterization of 3D skull and brain motion during dynamic head vibration using magnetic resonance elastography. Magn Reson Med 2018; 80:2573-2585. [PMID: 29774594 DOI: 10.1002/mrm.27347] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 04/08/2018] [Accepted: 04/13/2018] [Indexed: 12/17/2022]
Abstract
PURPOSE To introduce newly developed MR elastography (MRE)-based dual-saturation imaging and dual-sensitivity motion encoding schemes to directly measure in vivo skull-brain motion, and to study the skull-brain coupling in volunteers with these approaches. METHODS Six volunteers were scanned with a high-performance compact 3T-MRI scanner. The skull-brain MRE images were obtained with a dual-saturation imaging where the skull and brain motion were acquired with fat- and water-suppression scans, respectively. A dual-sensitivity motion encoding scheme was applied to estimate the heavily wrapped phase in skull by the simultaneous acquisition of both low- and high-sensitivity phase during a single MRE exam. The low-sensitivity phase was used to guide unwrapping of the high-sensitivity phase. The amplitude and temporal phase delay of the rigid-body motion between the skull and brain was measured, and the skull-brain interface was visualized by slip interface imaging (SII). RESULTS Both skull and brain motion can be successfully acquired and unwrapped. The skull-brain motion analysis demonstrated the motion transmission from the skull to the brain is attenuated in amplitude and delayed. However, this attenuation (%) and delay (rad) were considerably greater with rotation (59 ± 7%, 0.68 ± 0.14 rad) than with translation (92 ± 5%, 0.04 ± 0.02 rad). With SII the skull-brain slip interface was not completely evident, and the slip pattern was spatially heterogeneous. CONCLUSION This study provides a framework for acquiring in vivo voxel-based skull and brain displacement using MRE that can be used to characterize the skull-brain coupling system for understanding of mechanical brain protection mechanisms, which has potential to facilitate risk management for future injury.
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Affiliation(s)
- Ziying Yin
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Yi Sui
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Joshua D Trzasko
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Phillip J Rossman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Armando Manduca
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - John Huston
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
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Tanner K. Perspective: The role of mechanobiology in the etiology of brain metastasis. APL Bioeng 2018; 2:031801. [PMID: 31069312 PMCID: PMC6324204 DOI: 10.1063/1.5024394] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/18/2018] [Indexed: 12/11/2022] Open
Abstract
Tumor latency and dormancy are obstacles to effective cancer treatment. In brain
metastases, emergence of a lesion can occur at varying intervals from diagnosis
and in some cases following successful treatment of the primary tumor. Genetic
factors that drive brain metastases have been identified, such as those involved
in cell adhesion, signaling, extravasation, and metabolism. From this wealth of
knowledge, vexing questions still remain; why is there a difference in strategy
to facilitate outgrowth and why is there a difference in latency? One missing
link may be the role of tissue biophysics of the brain microenvironment in
infiltrating cells. Here, I discuss the mechanical cues that may influence
disseminated tumor cells in the brain, as a function of age and disease. I
further discuss in vitro and in vivo
preclinical models such as 3D culture systems and zebrafish to study the role of
the mechanical environment in brain metastasis in an effort of providing novel
targeted therapeutics.
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Affiliation(s)
- Kandice Tanner
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Johnson CL, Schwarb H, Horecka KM, McGarry MDJ, Hillman CH, Kramer AF, Cohen NJ, Barbey AK. Double dissociation of structure-function relationships in memory and fluid intelligence observed with magnetic resonance elastography. Neuroimage 2018; 171:99-106. [PMID: 29317306 PMCID: PMC5857428 DOI: 10.1016/j.neuroimage.2018.01.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 12/15/2017] [Accepted: 01/05/2018] [Indexed: 12/13/2022] Open
Abstract
Brain tissue mechanical properties, measured in vivo with magnetic resonance elastography (MRE), have proven to be sensitive metrics of neural tissue integrity. Recently, our group has reported on the positive relationship between viscoelasticity of the hippocampus and performance on a relational memory task in healthy young adults, which highlighted the potential of sensitive MRE measures for studying brain health and its relation to cognitive function; however, structure-function relationships outside of the hippocampus have not yet been explored. In this study, we examined the relationships between viscoelasticity of both the hippocampus and the orbitofrontal cortex and performance on behavioral assessments of relational memory and fluid intelligence. In a sample of healthy, young adults (N = 53), there was a significant, positive relationship between orbitofrontal cortex viscoelasticity and fluid intelligence performance (r = 0.42; p = .002). This finding is consistent with the previously reported relationship between hippocampal viscoelasticity and relational memory performance (r = 0.41; p = .002). Further, a significant double dissociation between the orbitofrontal-fluid intelligence relationship and the hippocampal-relational memory relationship was observed. These data support the specificity of regional brain MRE measures in support of separable cognitive functions. This report of a structure-function relationship observed with MRE beyond the hippocampus suggests a future role for MRE as a sensitive neuroimaging technique for brain mapping.
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Affiliation(s)
- Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States.
| | - Hillary Schwarb
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
| | - Kevin M Horecka
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Matthew D J McGarry
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
| | - Charles H Hillman
- Department of Psychology, Northeastern University, Boston, MA, United States; Department of Health Sciences, Northeastern University, Boston, MA, United States
| | - Arthur F Kramer
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States; Department of Psychology, Northeastern University, Boston, MA, United States
| | - Neal J Cohen
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Aron K Barbey
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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Laksari K, Kurt M, Babaee H, Kleiven S, Camarillo D. Mechanistic Insights into Human Brain Impact Dynamics through Modal Analysis. PHYSICAL REVIEW LETTERS 2018; 120:138101. [PMID: 29694192 DOI: 10.1103/physrevlett.120.138101] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 10/26/2017] [Indexed: 06/08/2023]
Abstract
Although concussion is one of the greatest health challenges today, our physical understanding of the cause of injury is limited. In this Letter, we simulated football head impacts in a finite element model and extracted the most dominant modal behavior of the brain's deformation. We showed that the brain's deformation is most sensitive in low frequency regimes close to 30 Hz, and discovered that for most subconcussive head impacts, the dynamics of brain deformation is dominated by a single global mode. In this Letter, we show the existence of localized modes and multimodal behavior in the brain as a hyperviscoelastic medium. This dynamical phenomenon leads to strain concentration patterns, particularly in deep brain regions, which is consistent with reported concussion pathology.
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Affiliation(s)
- Kaveh Laksari
- Department of Bioemedical Engineering, University of Arizona, Tucson, Arizona 95719, USA
| | - Mehmet Kurt
- Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA
| | - Hessam Babaee
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - Svein Kleiven
- Division of Neuronic Engineering, KTH-Royal Institute of Technology, Huddinge 114 28, Sweden
| | - David Camarillo
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA
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40
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Guertler CA, Okamoto RJ, Schmidt JL, Badachhape AA, Johnson CL, Bayly PV. Mechanical properties of porcine brain tissue in vivo and ex vivo estimated by MR elastography. J Biomech 2018; 69:10-18. [PMID: 29395225 DOI: 10.1016/j.jbiomech.2018.01.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/27/2017] [Accepted: 01/08/2018] [Indexed: 11/29/2022]
Abstract
The mechanical properties of brain tissue in vivo determine the response of the brain to rapid skull acceleration. These properties are thus of great interest to the developers of mathematical models of traumatic brain injury (TBI) or neurosurgical simulations. Animal models provide valuable insight that can improve TBI modeling. In this study we compare estimates of mechanical properties of the Yucatan mini-pig brain in vivo and ex vivo using magnetic resonance elastography (MRE) at multiple frequencies. MRE allows estimations of properties in soft tissue, either in vivo or ex vivo, by imaging harmonic shear wave propagation. Most direct measurements of brain mechanical properties have been performed using samples of brain tissue ex vivo. It has been observed that direct estimates of brain mechanical properties depend on the frequency and amplitude of loading, as well as the time post-mortem and condition of the sample. Using MRE in the same animals at overlapping frequencies, we observe that porcine brain tissue in vivo appears stiffer than porcine brain tissue samples ex vivo at frequencies of 100 Hz and 125 Hz, but measurements show closer agreement at lower frequencies.
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Affiliation(s)
- Charlotte A Guertler
- Washington University in St. Louis, Mechanical Engineering and Materials Science, United States.
| | - Ruth J Okamoto
- Washington University in St. Louis, Mechanical Engineering and Materials Science, United States
| | - John L Schmidt
- Washington University in St. Louis, Mechanical Engineering and Materials Science, United States
| | | | | | - Philip V Bayly
- Washington University in St. Louis, Mechanical Engineering and Materials Science, United States; Washington University in St. Louis, Biomedical Engineering, United States
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41
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Weickenmeier J, Kurt M, Ozkaya E, Wintermark M, Pauly KB, Kuhl E. Magnetic resonance elastography of the brain: A comparison between pigs and humans. J Mech Behav Biomed Mater 2018; 77:702-710. [DOI: 10.1016/j.jmbbm.2017.08.029] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/23/2017] [Accepted: 08/23/2017] [Indexed: 12/12/2022]
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Madhukar A, Chen Y, Ostoja-Starzewski M. Effect of cerebrospinal fluid modeling on spherically convergent shear waves during blunt head trauma. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33. [PMID: 28294580 DOI: 10.1002/cnm.2881] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 02/19/2017] [Accepted: 03/10/2017] [Indexed: 06/06/2023]
Abstract
The MRI-based computational model, previously validated by tagged MRI and harmonic phase imaging analysis technique on in vivo human brain deformation, is used to study transient wave dynamics during blunt head trauma. Three different constitutive models are used for the cerebrospinal fluid: incompressible solid elastic, viscoelastic, and fluid-like elastic using an equation of state model. Three impact cases are simulated, which indicate that the blunt impacts give rise not only to a fast pressure wave but also to a slow, and potentially much more damaging, shear (distortional) wave that converges spherically towards the brain center. The wave amplification due to spherical geometry is balanced by damping due to tissues' viscoelasticity and the heterogeneous brain structure, suggesting a stochastic competition of these 2 opposite effects. It is observed that this convergent shear wave is dependent on the constitutive property of the cerebrospinal fluid, whereas the peak pressure is not as significantly affected.
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Affiliation(s)
- Amit Madhukar
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Ying Chen
- Department of Mechanical Science and Engineering and Beckman Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Martin Ostoja-Starzewski
- Department of Mechanical Science and Engineering and Beckman Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA
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43
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Badachhape AA, Okamoto RJ, Durham RS, Efron BD, Nadell SJ, Johnson CL, Bayly PV. The Relationship of Three-Dimensional Human Skull Motion to Brain Tissue Deformation in Magnetic Resonance Elastography Studies. J Biomech Eng 2017; 139:2610238. [PMID: 28267188 DOI: 10.1115/1.4036146] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Indexed: 12/13/2022]
Abstract
In traumatic brain injury (TBI), membranes such as the dura mater, arachnoid mater, and pia mater play a vital role in transmitting motion from the skull to brain tissue. Magnetic resonance elastography (MRE) is an imaging technique developed for noninvasive estimation of soft tissue material parameters. In MRE, dynamic deformation of brain tissue is induced by skull vibrations during magnetic resonance imaging (MRI); however, skull motion and its mode of transmission to the brain remain largely uncharacterized. In this study, displacements of points in the skull, reconstructed using data from an array of MRI-safe accelerometers, were compared to displacements of neighboring material points in brain tissue, estimated from MRE measurements. Comparison of the relative amplitudes, directions, and temporal phases of harmonic motion in the skulls and brains of six human subjects shows that the skull-brain interface significantly attenuates and delays transmission of motion from skull to brain. In contrast, in a cylindrical gelatin "phantom," displacements of the rigid case (reconstructed from accelerometer data) were transmitted to the gelatin inside (estimated from MRE data) with little attenuation or phase lag. This quantitative characterization of the skull-brain interface will be valuable in the parameterization and validation of computer models of TBI.
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Affiliation(s)
- Andrew A Badachhape
- Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63105 e-mail:
| | - Ruth J Okamoto
- Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63105
| | - Ramona S Durham
- Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63105
| | - Brent D Efron
- Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63105
| | - Sam J Nadell
- Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63105
| | - Curtis L Johnson
- Biomedical Engineering, University of Delaware, Newark, DE 19716
| | - Philip V Bayly
- Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63105;Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO 63105
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44
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Pepin KM, McGee KP, Arani A, Lake DS, Glaser KJ, Manduca A, Parney IF, Ehman RL, Huston J. MR Elastography Analysis of Glioma Stiffness and IDH1-Mutation Status. AJNR Am J Neuroradiol 2017; 39:31-36. [PMID: 29074637 DOI: 10.3174/ajnr.a5415] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/13/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND PURPOSE Our aim was to noninvasively evaluate gliomas with MR elastography to characterize the relationship of tumor stiffness with tumor grade and mutations in the isocitrate dehydrogenase 1 (IDH1) gene. MATERIALS AND METHODS Tumor stiffness properties were prospectively quantified in 18 patients (mean age, 42 years; 6 women) with histologically proved gliomas using MR elastography from 2014 to 2016. Images were acquired on a 3T MR imaging unit with a vibration frequency of 60 Hz. Tumor stiffness was compared with unaffected contralateral white matter, across tumor grade, and by IDH1-mutation status. The performance of the use of tumor stiffness to predict tumor grade and IDH1 mutation was evaluated with the Wilcoxon rank sum, 1-way ANOVA, and Tukey-Kramer tests. RESULTS Gliomas were softer than healthy brain parenchyma, 2.2 kPa compared with 3.3 kPa (P < .001), with grade IV tumors softer than grade II. Tumors with an IDH1 mutation were significantly stiffer than those with wild type IDH1, 2.5 kPa versus 1.6 kPa, respectively (P = .007). CONCLUSIONS MR elastography demonstrated that not only were gliomas softer than normal brain but the degree of softening was directly correlated with tumor grade and IDH1-mutation status. Noninvasive determination of tumor grade and IDH1 mutation may result in improved stratification of patients for different treatment options and the evaluation of novel therapeutics. This work reports on the emerging field of "mechanogenomics": the identification of genetic features such as IDH1 mutation using intrinsic biomechanical information.
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Affiliation(s)
- K M Pepin
- From the Mayo Graduate School (K.M.P.)
| | - K P McGee
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
| | - A Arani
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
| | - D S Lake
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
| | - K J Glaser
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
| | - A Manduca
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
| | - I F Parney
- Neurosurgery (I.F.P.), Mayo Clinic College of Medicine, Rochester, Minnesota
| | - R L Ehman
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
| | - J Huston
- Departments of Radiology (K.P.M., A.A., D.S.L., K.J.G., A.M., R.L.E., J.H.)
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45
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Testu J, McGarry M, Dittmann F, Weaver J, Paulsen K, Sack I, Van Houten E. Viscoelastic power law parameters of in vivo human brain estimated by MR elastography. J Mech Behav Biomed Mater 2017; 74:333-341. [DOI: 10.1016/j.jmbbm.2017.06.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/19/2017] [Accepted: 06/20/2017] [Indexed: 02/06/2023]
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46
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Chartrain AG, Kurt M, Yao A, Feng R, Nael K, Mocco J, Bederson JB, Balchandani P, Shrivastava RK. Utility of preoperative meningioma consistency measurement with magnetic resonance elastography (MRE): a review. Neurosurg Rev 2017; 42:1-7. [DOI: 10.1007/s10143-017-0862-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 04/06/2017] [Accepted: 05/10/2017] [Indexed: 10/19/2022]
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47
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Tweten DJ, Okamoto RJ, Bayly PV. Requirements for accurate estimation of anisotropic material parameters by magnetic resonance elastography: A computational study. Magn Reson Med 2017; 78:2360-2372. [PMID: 28097687 DOI: 10.1002/mrm.26600] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 11/22/2016] [Accepted: 12/13/2016] [Indexed: 12/27/2022]
Abstract
PURPOSE To establish the essential requirements for characterization of a transversely isotropic material by magnetic resonance elastography (MRE). THEORY AND METHODS Three methods for characterizing nearly incompressible, transversely isotropic (ITI) materials were used to analyze data from closed-form expressions for traveling waves, finite-element (FE) simulations of waves in homogeneous ITI material, and FE simulations of waves in heterogeneous material. Key properties are the complex shear modulus μ2 , shear anisotropy ϕ=μ1/μ2-1, and tensile anisotropy ζ=E1/E2-1. RESULTS Each method provided good estimates of ITI parameters when both slow and fast shear waves with multiple propagation directions were present. No method gave accurate estimates when the displacement field contained only slow shear waves, only fast shear waves, or waves with only a single propagation direction. Methods based on directional filtering are robust to noise and include explicit checks of propagation and polarization. Curl-based methods led to more accurate estimates in low noise conditions. Parameter estimation in heterogeneous materials is challenging for all methods. CONCLUSIONS Multiple shear waves, both slow and fast, with different propagation directions, must be present in the displacement field for accurate parameter estimates in ITI materials. Experimental design and data analysis can ensure that these requirements are met. Magn Reson Med 78:2360-2372, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- D J Tweten
- Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri, USA
| | - R J Okamoto
- Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri, USA
| | - P V Bayly
- Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri, USA.,Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
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48
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49
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Forte AE, Gentleman SM, Dini D. On the characterization of the heterogeneous mechanical response of human brain tissue. Biomech Model Mechanobiol 2016; 16:907-920. [PMID: 27933417 PMCID: PMC5422507 DOI: 10.1007/s10237-016-0860-8] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 11/21/2016] [Indexed: 01/19/2023]
Abstract
The mechanical characterization of brain tissue is a complex task that scientists have tried to accomplish for over 50 years. The results in the literature often differ by orders of magnitude because of the lack of a standard testing protocol. Different testing conditions (including humidity, temperature, strain rate), the methodology adopted, and the variety of the species analysed are all potential sources of discrepancies in the measurements. In this work, we present a rigorous experimental investigation on the mechanical properties of human brain, covering both grey and white matter. The influence of testing conditions is also shown and thoroughly discussed. The material characterization performed is finally adopted to provide inputs to a mathematical formulation suitable for numerical simulations of brain deformation during surgical procedures.
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Affiliation(s)
- Antonio E Forte
- Department of Mechanical Engineering, Imperial College London, London, SW7 2AZ, UK.
| | | | - Daniele Dini
- Department of Mechanical Engineering, Imperial College London, London, SW7 2AZ, UK
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50
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Hiscox LV, Johnson CL, Barnhill E, McGarry MDJ, Huston J, van Beek EJR, Starr JM, Roberts N. Magnetic resonance elastography (MRE) of the human brain: technique, findings and clinical applications. Phys Med Biol 2016; 61:R401-R437. [DOI: 10.1088/0031-9155/61/24/r401] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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