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Hojo E, Sui Y, Shan X, Zheng K, Rossman P, Manduca A, Powell GM, An KN, Zhao KD, Bauer BA, Ehman RL, Yin Z. MR elastography-based slip interface imaging (SII) for functional assessment of myofascial interfaces: A feasibility study. Magn Reson Med 2024; 92:676-687. [PMID: 38523575 PMCID: PMC11142878 DOI: 10.1002/mrm.30087] [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: 12/10/2023] [Revised: 02/28/2024] [Accepted: 02/28/2024] [Indexed: 03/26/2024]
Abstract
PURPOSE Abnormal adherence at functional myofascial interfaces is hypothesized as an important phenomenon in myofascial pain syndrome. This study aimed to investigate the feasibility of MR elastography (MRE)-based slip interface imaging (SII) to visualize and assess myofascial mobility in healthy volunteers. METHODS SII was used to assess local shear strain at functional myofascial interfaces in the flexor digitorum profundus (FDP) and thighs. In the FDP, MRE was performed at 90 Hz vibration to each index, middle, ring, and little finger. Two thigh MRE scans were performed at 40 Hz with knees flexed and extended. The normalized octahedral shear strain (NOSS) maps were calculated to visualize myofascial slip interfaces. The entropy of the probability distribution of the gradient NOSS was computed for the two knee positions at the intermuscular interface between vastus lateralis and vastus intermedius, around rectus femoris, and between vastus intermedius and vastus medialis. RESULTS NOSS map depicted distinct functional slip interfaces in the FDP for each finger. Compared to knee flexion, clearer slip interfaces and larger gradient NOSS entropy at the vastus lateralis-vastus intermedius interface were observed during knee extension, where the quadriceps are not passively stretched. This suggests the optimal position for using SII to visualize myofascial slip interface in skeletal muscles is when muscles are not subjected to any additional force. CONCLUSION The study demonstrated that MRE-based SII can visualize and assess myofascial interface mobility in extremities. The results provide a foundation for investigating the hypothesis that myofascial pain syndrome is characterized by changes in the mobility of myofascial interfaces.
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Affiliation(s)
- Emi Hojo
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Yi Sui
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Xiang Shan
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Keni Zheng
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Phillip 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
| | - Garret M. Powell
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Kai-Nan An
- Orthopedics Research, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Kristin D. Zhao
- Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Brent A. Bauer
- General Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Richard L. Ehman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Ziying Yin
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
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Zhang Y, Chen M, Liu H, He Y, Li Y, Shen P, Chen Y, Huang J, Liu C. Effect of different isometric trunk extension intensities on the muscle stiffness of the lumbar and lower limbs. Front Physiol 2024; 14:1337170. [PMID: 38239887 PMCID: PMC10794496 DOI: 10.3389/fphys.2023.1337170] [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: 11/12/2023] [Accepted: 12/15/2023] [Indexed: 01/22/2024] Open
Abstract
Purpose: To investigate the effect of isometric prone trunk extension (IPTE) contraction intensity on the stiffness of erector spinae (ES), semitendinosus (ST), biceps femoris (BF), and gastrocnemius muscles to understand the overall muscle mechanical behavior during IPTE and to explore the mechanisms of oordinated contraction of the body kinetic chain. Methods: Twenty healthy females were recruited, and participants underwent IPTE at three contraction intensities, i.e., 0% maximum voluntary isometric contraction (MVIC), 30% MVIC, and 60% MVIC, and muscle stiffness was measured using MyotonPRO. Results: Muscle stiffness was moderately to strongly positively correlated with contraction intensity (r = 0.408-0.655, p < 0.001). The percentage increase in stiffness at low intensity was much greater in ES than in lower limb muscles and greater in ST and BF than in gastrocnemius, whereas at moderate intensity, the percentage increase in stiffness decreased in all muscles, and the percentage increase in stiffness in ES was lower than that in ST. There was a moderate to strong positive correlation between ES stiffness variation and ST (r = 0.758-0.902, p < 0.001), BF (r = 0.454-0.515, p < 0.05), MG (r = 0.643-0.652, p < 0.01), LG (r = 0.659-0.897, p < 0.01). Conclusion: IPTE significantly affected the stiffness of lumbar and lower limb muscles, and low-intensity IPTE activated the ES more efficiently. There were significant coordinated muscle contractions between ES, ST, and LG. This provides preliminary evidence for exploring the overall modulation pattern of the lumbar and lower limb muscles' kinetic chains. In future studies, we will combine other stiffness assessment methods (such as Magnetic Resonance Elastography, Shear Wave Elastography, or electromyography) to corroborate our findings.
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Affiliation(s)
| | | | | | | | | | | | | | - Jiapeng Huang
- Clinical Medical College of Acupuncture, Moxibustion, and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
| | - Chunlong Liu
- Clinical Medical College of Acupuncture, Moxibustion, and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, China
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Chevalier B, Bedretdinova D, Pellot-Barakat C, Maître X, Creze M. Evaluation of the Reproducibility of MR Elastography Measurements of the Lumbar Back Muscles. J Magn Reson Imaging 2023. [PMID: 38100302 DOI: 10.1002/jmri.29178] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/21/2023] [Accepted: 11/22/2023] [Indexed: 12/17/2023] Open
Abstract
BACKGROUND MR elastography (MRE) may provide quantitative imaging biomarkers of lumbar back muscles (LBMs), complementing MRI in spinal diseases by assessing muscle mechanical properties. However, reproducibility analyses for MRE of LBM are lacking. PURPOSE To assess technical failure, within-day and inter-day reproducibility, robustness with the excitation source positioning, and inter-observer agreement of MRE of muscles. STUDY TYPE Prospective. SUBJECTS Seventeen healthy subjects (mean age 28 ± 4 years; 11 females). FIELD STRENGTH/SEQUENCE 1.5 T, gradient-echo MRE, T1-weighted turbo spin echo. ASSESSMENT The pneumatic driver was centered at L3 level. Four MRE were performed during two visits, 2-4 weeks apart, each consisting of two MRE with less than 10 minutes inter-scan interval. At Visit 1, after the first MRE, the coil and driver were removed, then reinstalled. The MRE was repeated. At Visit 2, following the first MRE, only the driver was moved down 5 cm. The MRE was repeated. Two radiologists segmented the multifidus and erector spinae muscles. STATISTICAL TESTS Paired t-test, analysis of variance, intraclass correlation coefficients (ICCs). P-values <0.05 were considered statistically significant. RESULTS Mean stiffness of LBM ranged from 1.44 to 1.60 kPa. Mean technical failure rate was 2.5%. Inter-observer agreement was excellent (ICC ranging from 0.82 [0.64-0.96] to 0.99 [0.98-0.99] in the multifidus, and from 0.85 [0.69-0.92] to 0.99 [0.97-0.99] in the erector spinae muscles). Within-day reproducibility was fair in the multifidus (ICC: 0.53 [0.47-0.77]) and good in the erector spinae muscles (ICC: 0.74 [0.48-0.88]). Reproducibility after moving the driver was excellent in both multifidus (ICC: 0.85 [0.69-0.93]) and erector spinae muscles (ICC: 0.84 [0.67-0.92]). Inter-day reproducibility was excellent in the multifidus (ICC: 0.76 [0.48-0.89]) and poor in the erector spinae muscles (ICC: 0.23 [-0.61 to 0.63]). DATA CONCLUSION MRE of LBM provides measurements of stiffness with fair to excellent reproducibility and excellent inter-observer agreement. However, inter-day reproducibility in the multifidus muscles indicated that the herein used MRE protocol may not be optimal for this muscle. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Benjamin Chevalier
- Department of Radiology, Cochin Hospital, Université Paris Cité, APHP, Paris, France
| | - Dina Bedretdinova
- Center for Research in Epidemiology and StatisticS (CRESS), Université Paris Cité and Université Sorbonne Paris Nord, Inserm, INRAE, Paris, France
| | - Claire Pellot-Barakat
- Laboratoire d'Imagerie Biomédicale Multimodale, BIOMAPS, Université Paris-Saclay, Service Hospitalier Frederic Joliot, Orsay, France
| | - Xavier Maître
- Laboratoire d'Imagerie Biomédicale Multimodale, BIOMAPS, Université Paris-Saclay, Service Hospitalier Frederic Joliot, Orsay, France
| | - Maud Creze
- Laboratoire d'Imagerie Biomédicale Multimodale, BIOMAPS, Université Paris-Saclay, Service Hospitalier Frederic Joliot, Orsay, France
- Department of Radiology, Bicêtre Hospital, Université Paris-Saclay, APHP, Le Kremlin Bicêtre, France
- Arts et Métiers Institute of Technology, Université Sorbonne Paris Nord, IBHGC - Institut de Biomécanique Humaine Georges Charpak, HESAM Université, Paris, France
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Blank J, Blomquist M, Arant L, Cone S, Roth J. Characterizing Musculoskeletal Tissue Mechanics Based on Shear Wave Propagation: A Systematic Review of Current Methods and Reported Measurements. Ann Biomed Eng 2022; 50:751-768. [PMID: 35359250 DOI: 10.1007/s10439-022-02935-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/11/2022] [Indexed: 12/17/2022]
Abstract
Developing methods for the non-invasive characterization of the mechanics of musculoskeletal tissues is an ongoing research focus in biomechanics. Often, these methods use the speed of shear wave propagation to characterize tissue mechanics (e.g., shear wave elastography and shear wave tensiometry). The primary purpose of this systematic review was to identify, compare, and contrast current methods for exciting and measuring shear wave propagation in musculoskeletal tissues. We conducted searches in the Web of Science, PubMed, and Scopus databases for studies published from January 1, 1900, to May 1, 2020. These searches targeted both shear wave excitation using acoustic pushes and mechanical taps, and shear wave speed measurement using ultrasound, magnetic resonance imaging, accelerometers, and laser Doppler vibrometers. Two reviewers independently screened and reviewed the articles, identifying 524 articles that met our search criteria. Regarding shear wave excitation, we found that acoustic pushes are useful for exciting shear waves through the thickness of the tissue of interest, and mechanical taps are useful for exciting shear waves in wearable applications. Regarding shear wave speed measurement, we found that ultrasound is used most broadly to measure shear waves due to its ability to study regional differences and target specific tissues of interest. The strengths of magnetic resonance imaging, accelerometers, and laser Doppler vibrometers make them advantageous to measure shear wave speeds for high-resolution shear wave imaging, wearable measurements, and non-contact ex vivo measurements, respectively. The advantages that each method offers for exciting and measuring shear waves indicate that a variety of systems can be assembled using currently available technologies to determine musculoskeletal tissue material behavior across a range of innovative applications.
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Affiliation(s)
- Jonathon Blank
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Matthew Blomquist
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Lesley Arant
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Stephanie Cone
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Joshua Roth
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA. .,Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1111 Highland Ave WIMR 5037, Madison, WI, 53705, USA.
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Babaei B, Fovargue D, Lloyd RA, Miller R, Jugé L, Kaplan M, Sinkus R, Nordsletten DA, Bilston LE. Magnetic Resonance Elastography Reconstruction for Anisotropic Tissues. Med Image Anal 2021; 74:102212. [PMID: 34587584 DOI: 10.1016/j.media.2021.102212] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 06/02/2021] [Accepted: 08/04/2021] [Indexed: 12/19/2022]
Abstract
Elastography has become widely used clinically for characterising changes in soft tissue mechanics that are associated with altered tissue structure and composition. However, some soft tissues, such as muscle, are not isotropic as is assumed in clinical elastography implementations. This limits the ability of these methods to capture changes in anisotropic tissues associated with disease. The objective of this study was to develop and validate a novel elastography reconstruction technique suitable for estimating the linear viscoelastic mechanical properties of transversely isotropic soft tissues. We derived a divergence-free formulation of the governing equations for acoustic wave propagation through a linearly transversely isotropic viscoelastic material, and transformed this into a weak form. This was then implemented into a finite element framework, enabling the analysis of wave input data and tissue structural fibre orientations, in this case based on diffusion tensor imaging. To validate the material constants obtained with this method, numerous in silico phantom experiments were run which encompassed a range of variations in wave input directions, material properties, fibre structure and noise. The method was also tested on ex vivo muscle and in vivo human volunteer calf muscles, and compared with a previous curl-based inversion method. The new method robustly extracted the transversely isotropic shear moduli (G⊥', G∥', G″) from the in silico phantom tests with minimal bias, including in the presence of experimentally realistic levels of noise in either fibre orientation or wave data. This new method performed better than the previous method in the presence of noise. Anisotropy estimates from the ex vivo muscle phantom agreed well with rheological tests. In vivo experiments on human calf muscles were able to detect increases in muscle shear moduli with passive muscle stretch. This new reconstruction method can be applied to quantify tissue mechanical properties of anisotropic soft tissues, such as muscle, in health and disease.
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Affiliation(s)
- Behzad Babaei
- Neuroscience Research Australia, Sydney, NSW, Australia; School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Daniel Fovargue
- School of Biomedical Engineering and Imaging Sciences, The Rayne Institute, King's College London, SE1 7EH, London, United Kingdom
| | - Robert A Lloyd
- Neuroscience Research Australia, Sydney, NSW, Australia; Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Renee Miller
- School of Biomedical Engineering and Imaging Sciences, The Rayne Institute, King's College London, SE1 7EH, London, United Kingdom
| | - Lauriane Jugé
- School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Max Kaplan
- Neuroscience Research Australia, Sydney, NSW, Australia; Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
| | - Ralph Sinkus
- School of Biomedical Engineering and Imaging Sciences, The Rayne Institute, King's College London, SE1 7EH, London, United Kingdom
| | - David A Nordsletten
- School of Biomedical Engineering and Imaging Sciences, The Rayne Institute, King's College London, SE1 7EH, London, United Kingdom; Department of Surgery and Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Lynne E Bilston
- Neuroscience Research Australia, Sydney, NSW, Australia; Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia.
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Schrank F, Warmuth C, Görner S, Meyer T, Tzschätzsch H, Guo J, Uca YO, Elgeti T, Braun J, Sack I. Real‐time MR elastography for viscoelasticity quantification in skeletal muscle during dynamic exercises. Magn Reson Med 2019; 84:103-114. [DOI: 10.1002/mrm.28095] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/29/2019] [Accepted: 11/03/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Felix Schrank
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Carsten Warmuth
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Steffen Görner
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Tom Meyer
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Heiko Tzschätzsch
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Jing Guo
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Yavuz Oguz Uca
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Thomas Elgeti
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
| | - Jürgen Braun
- Institute of Medical Informatics Charité–Universitätsmedizin Berlin Berlin Germany
| | - Ingolf Sack
- Department of Radiology Charité–Universitätsmedizin Berlin Berlin Germany
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Zonnino A, Smith DR, Delgorio PL, Johnson CL, Sergi F. MM-MRE: a new technique to quantify individual muscle forces during isometric tasks of the wrist using MR elastography. IEEE Int Conf Rehabil Robot 2019; 2019:270-275. [PMID: 31374641 PMCID: PMC7901716 DOI: 10.1109/icorr.2019.8779562] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Non-invasive in-vivo measurement of individual muscle force is limited by the infeasibility of placing force sensing elements in series with the musculo-tendon structures. While different methods based either on shear wave elastography or electromyography have been recently proposed to non-invasively estimate individual muscle forces, they can only be used to quantity forces in a limited set of superficial muscles. As such, they are not suitable to study the neuromuscular control of movements that require coordinated action of multiple muscles. In this work, we present multi-muscle magnetic resonance elastography (MM-MRE), a new technique capable of quantifying force for each muscle in the forearm, thus enabling the study of the neuromuscular control of wrist movements. To quantity individual muscle force, MM-MRE integrates measurements of joint torque provided by an MRI-compatible instrumented handle with muscle-specific measurements of shear wave speed obtained via MRE into a forward dynamic muscle force estimator based on a realistic musculoskeletal model of the forearm. A single-subject pilot experiment demonstrates the possibility of obtaining measurements from individual muscles and establishes that MM-MRE has sufficient sensitivity to detect changes in the muscle specific measurement of shear-wave speed following the application of isometric flexion and extension torques with self-selected intensity.
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8
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Guenthner C, Kozerke S. Encoding and readout strategies in magnetic resonance elastography. NMR IN BIOMEDICINE 2018; 31:e3919. [PMID: 29806865 DOI: 10.1002/nbm.3919] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 12/15/2017] [Accepted: 02/15/2018] [Indexed: 06/08/2023]
Abstract
Magnetic resonance elastography (MRE) has evolved significantly since its inception. Advances in motion-encoding gradient design and readout strategies have led to improved encoding and signal-to-noise ratio (SNR) efficiencies, which in turn allow for higher spatial resolution, increased coverage, and/or shorter scan times. The purpose of this review is to summarize MRE wave-encoding and readout approaches in a unified mathematical framework to allow for a comparative assessment of encoding and SNR efficiency of the various methods available. Besides standard full- and fractional-wave-encoding approaches, advanced techniques including flow compensation, sample interval modulation and multi-shot encoding are considered. Signal readout using fast k-space trajectories, reduced field of view, multi-slice, and undersampling techniques are summarized and put into perspective. The review is concluded with a foray into displacement and diffusion encoding as alternative and/or complementary techniques.
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Affiliation(s)
- Christian Guenthner
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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Creze M, Soubeyrand M, Yue JL, Gagey O, Maître X, Bellin MF. Magnetic resonance elastography of the lumbar back muscles: A preliminary study. Clin Anat 2018; 31:514-520. [DOI: 10.1002/ca.23065] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 02/07/2018] [Accepted: 02/13/2018] [Indexed: 12/26/2022]
Affiliation(s)
- Maud Creze
- Radiology Department; Bicêtre Hospital; APHP France
- Imagerie par Résonance Magnétique Médicale et Multi-Modalités, IR4M, CNRS, Univ Paris-Sud, Université Paris-Saclay; Orsay France
| | | | - Jin Long Yue
- Imagerie par Résonance Magnétique Médicale et Multi-Modalités, IR4M, CNRS, Univ Paris-Sud, Université Paris-Saclay; Orsay France
- Imagerie Moléculaire In Vivo, IMIV, Inserm, CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay; Orsay France
| | - Olivier Gagey
- Orthopedic Department; Bicêtre Hospital; APHP France
| | - Xavier Maître
- Imagerie par Résonance Magnétique Médicale et Multi-Modalités, IR4M, CNRS, Univ Paris-Sud, Université Paris-Saclay; Orsay France
| | - Marie-France Bellin
- Radiology Department; Bicêtre Hospital; APHP France
- Imagerie par Résonance Magnétique Médicale et Multi-Modalités, IR4M, CNRS, Univ Paris-Sud, Université Paris-Saclay; Orsay France
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Age and Sex Effects on the Active Stiffness of Vastus Intermedius under Isometric Contraction. BIOMED RESEARCH INTERNATIONAL 2017; 2017:9469548. [PMID: 28473990 PMCID: PMC5394906 DOI: 10.1155/2017/9469548] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/30/2016] [Accepted: 03/16/2017] [Indexed: 12/03/2022]
Abstract
Previously, a novel technique was proposed to quantify the relationship between the muscle stiffness and its nonfatigue contraction intensity. The method extended the measured range of isometric contraction to 100% maximum voluntary contraction (MVC) using an ultrasonic shear wave measurement setup. Yet, it has not been revealed how this relationship could be affected by factors like age or sex. To clarify these questions, vastus intermedius (VI) stiffness of 40 healthy subjects was assessed under 11 step levels of isometric contraction. The subjects were divided into four groups: young males, young females, elderly males, and elderly females (n = 10 for each). In a relaxed state, no significant difference was observed between the male and female subjects (p = 0.156) nor between the young and elderly subjects (p = 0.221). However, when performing isometric contraction, the VI stiffness of males was found to be significantly higher than that of females at the same level (p < 0.001), and that of the young was higher than the elderly (p < 0.001). Meanwhile, for two knee joint angles used, the stiffness measured at a 90° knee joint angle was always significantly larger than that measured at 60° (p < 0.001). Recognizing the active muscle stiffness of VI contributes to body stability, and these results may provide insight into the age and sex bias in musculoskeletal studies, such as those on fall risks.
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Bosshard JC, Yallapragada N, McDougall MP, Wright SM. Exploration of highly accelerated magnetic resonance elastography using high-density array coils. Quant Imaging Med Surg 2017; 7:195-204. [PMID: 28516045 PMCID: PMC5418148 DOI: 10.21037/qims.2017.04.02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 04/07/2017] [Indexed: 11/06/2022]
Abstract
BACKGROUND Magnetic resonance elastography (MRE) measures tissue mechanical properties by applying a shear wave and capturing its propagation using magnetic resonance imaging (MRI). By using high density array coils, MRE images are acquired using single echo acquisition (SEA) and at high resolutions with significantly reduced scan times. METHODS Sixty-four channel uniplanar and 32×32 channel biplanar receive arrays are used to acquire MRE wave image sets from agar samples containing regions of varying stiffness. A mechanical actuator triggered by a stepped delay time introduces vibrations into the sample while a motion sensitizing gradient encodes micrometer displacements into the phase. SEA imaging is used to acquire each temporal offset in a single echo, while multiple echoes from the same array are employed for highly accelerated imaging at high resolutions. Additionally, stiffness variations as a function of temperature are studied by using a localized heat source above the sample. A custom insertable gradient coil is employed for phase compensation of SEA imaging with the biplanar array to allow imaging of multiple slices. RESULTS SEA MRE images show a mechanical shear wave propagating into and across agar samples. A set of 720 images was obtained in 720 echoes, plus a single reference scan for both harmonic and transient MRE. A set of 2,950 wave image frames was acquired from pairs of SEA images captured during heating, showing the change in mechanical wavelength with the change in agar properties. A set of 240 frames was acquired from two slices simultaneously using the biplanar array, with phase images processed into displacement maps. Combining the narrow sensitivity patterns and SNR advantage of the SEA array coil geometry allowed acquisition of a data set with a resolution of 156 µm × 125 µm × 1,000 µm in only 64 echoes, demonstrating high resolution and high acceleration factors. CONCLUSIONS MRE using high-density arrays offers the unique ability to acquire a single frame of a propagating mechanical vibration with each echo, which may be helpful in non-repeatable or destructive testing. Highly accelerated, high resolution MRE may be enabled by the use of large arrays of coils such as used for SEA, but at lower acceleration rates supporting the higher resolution than provided by SEA imaging.
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Affiliation(s)
- John C. Bosshard
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Naresh Yallapragada
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
| | - Mary P. McDougall
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Steven M. Wright
- Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- Department of Radiology, Texas A&M Health Science Center, Bryan, TX, USA
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Hug F, Tucker K, Gennisson JL, Tanter M, Nordez A. Elastography for Muscle Biomechanics: Toward the Estimation of Individual Muscle Force. Exerc Sport Sci Rev 2015; 43:125-33. [PMID: 25906424 DOI: 10.1249/jes.0000000000000049] [Citation(s) in RCA: 202] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Estimation of individual muscle force remains one of the main challenges in biomechanics. This review presents a series of experiments that used ultrasound shear wave elastography to support the hypothesis that muscle stiffness is linearly related to both active and passive muscle forces. Examples of studies that used measurement of muscle stiffness to estimate changes in muscle force are presented.
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Affiliation(s)
- François Hug
- 1University of Nantes, Laboratory "Movement, Interactions, Performance" (EA 4334), UFR STAPS, Nantes, France; 2The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Australia; 3The University of Queensland, School of Biomedical Sciences, Brisbane, Australia; and 4Institut Langevin-Ondes et images, ESPCI ParisTech, PSL Research University, CNRS UMR7587, INSERM U979, Université Paris VII, Paris, France
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Bensamoun S, Charleux F, Debernard L, Themar-Noel C, Voit T. Elastic properties of skeletal muscle and subcutaneous tissues in Duchenne muscular dystrophy by magnetic resonance elastography (MRE): A feasibility study. Ing Rech Biomed 2015. [DOI: 10.1016/j.irbm.2014.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Wang CZ, Li TJ, Zheng YP. Shear modulus estimation on vastus intermedius of elderly and young females over the entire range of isometric contraction. PLoS One 2014; 9:e101769. [PMID: 24991890 PMCID: PMC4081795 DOI: 10.1371/journal.pone.0101769] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/10/2014] [Indexed: 11/18/2022] Open
Abstract
Elderly people often suffer from sarcopenia in their lower extremities, which gives rise to the increased susceptibility of fall. Comparing the mechanical properties of the knee extensor/flexors on elderly and young subjects is helpful in understanding the underlying mechanisms of the muscle aging process. However, although the stiffness of skeletal muscle has been proved to be positively correlated to its non-fatiguing contraction intensity by some existing methods, this conclusion has not been verified above 50% maximum voluntary contraction (MVC) due to the limitation of their measurement range. In this study, a vibro-ultrasound system was set up to achieve a considerably larger measurement range on muscle stiffness estimation. Its feasibility was verified on self-made silicone phantoms by comparing with the mechanical indentation method. The system was then used to assess the stiffness of vastus intermedius (VI), one of the knee extensors, on 10 healthy elderly female subjects (56.7±4.9 yr) and 10 healthy young female subjects (27.6±5.0 yr). The VI stiffness in its action direction was confirmed to be positively correlated to the % MVC level (R2 = 0.999) over the entire range of isometric contraction, i.e. from 0% MVC (relaxed state) to 100% MVC. Furthermore, it was shown that there was no significant difference between the mean VI shear modulus of the elderly and young subjects in a relaxed state (p>0.1). However, when performing step isometric contraction, the VI stiffness of young female subjects was found to be larger than that of elderly participants (p<0.001), especially at the relatively higher contraction levels. The results expanded our knowledge on the mechanical property of the elderly’s skeletal muscle and its relationship with intensity of active contraction. Furthermore, the vibro-ultrasound system has a potential to become a powerful tool for investigating the elderly’s muscle diseases.
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Affiliation(s)
- Cong-Zhi Wang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- Interdisciplinary Division of Biomedical Engineering, the Hong Kong Polytechnic University, Hong Kong, China
- Beijing Center for Mathematics and Information Interdisciplinary Sciences, Beijing, China
- * E-mail: (CZW) (CW); (YPZ) (YZ)
| | - Tian-Jie Li
- Interdisciplinary Division of Biomedical Engineering, the Hong Kong Polytechnic University, Hong Kong, China
| | - Yong-Ping Zheng
- Interdisciplinary Division of Biomedical Engineering, the Hong Kong Polytechnic University, Hong Kong, China
- * E-mail: (CZW) (CW); (YPZ) (YZ)
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15
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Grenier R, Périé D, Gilbert G, Beaudoin G, Curnier D. Assessment of Mechanical Properties of Muscles from Multi-Parametric Magnetic Resonance Imaging. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/jbise.2014.78060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Bensamoun SF. Magnetic Resonance Elastography of the Skeletal Muscle. MAGNETIC RESONANCE ELASTOGRAPHY 2014:81-87. [DOI: 10.1007/978-1-4939-1575-0_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Bensamoun SF, Dao TT, Charleux F, Ho Ba Tho MC. ESTIMATION OF MUSCLE FORCE DERIVED FROM IN VIVO MR ELASTOGRAPHY TESTS: A PRELIMINARY STUDY. ACTA ACUST UNITED AC 2013. [DOI: 10.1142/s0218957713500152] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The objective is to estimate the vastus medialis (VM) muscle force from multifrequency magnetic resonance elastography (MMRE) tests and two different rheological models (Voigt and springpot). Healthy participants (N = 13) underwent multifrequency (70, 90 and 110 Hz) magnetic resonance elastography MMRE tests. Thus, in vivo experimental elastic (μ) properties of the VM in passive and active (20% MVC) conditions were characterized. Moreover, the muscle viscosity (η) was determined with Voigt and springpot rheological models, in both muscle states. Subsequently, the VM muscle forces were calculated with a generic musculoskeletal model (OpenSIM) where the active and passive shear moduli (μ) were implemented. The viscosity measured with the two rheological models increased when the muscle is contracted. During the stance and the swing phases, the VM tensile forces decrease and the VM force was lower with the springpot model. It can be noted that during the swing phase, the muscle forces estimated from springpot model showed a higher standard deviation compared to the Voigt model. This last result may indicate a strong sensitivity of the muscle force to the change of active and passive contractile components in the swing phase of gait. This study provides for the first time an estimation of the muscle tensile forces for lower limb, during human motion, from in vivo experimental muscle mechanical properties. The assessment of individualized muscle forces during motion is valuable for finite element models, increasing the patient specific parameters. This novel muscle database will be of use for the clinician to better elucidate the muscle pathophysiology and to better monitor the effects of the muscle disease.
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Affiliation(s)
- Sabine F. Bensamoun
- Biomechanics and Bioengineery Laboratory, UMR CNRS 7338, Université de Technologie de Compiègne, Compiègne, France
| | - Tien Tuan Dao
- Biomechanics and Bioengineery Laboratory, UMR CNRS 7338, Université de Technologie de Compiègne, Compiègne, France
| | | | - Marie-Christine Ho Ba Tho
- Biomechanics and Bioengineery Laboratory, UMR CNRS 7338, Université de Technologie de Compiègne, Compiègne, France
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18
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Leclerc GE, Debernard L, Foucart F, Robert L, Pelletier KM, Charleux F, Ehman R, Tho MCHB, Bensamoun SF. Characterization of a hyper-viscoelastic phantom mimicking biological soft tissue using an abdominal pneumatic driver with magnetic resonance elastography (MRE). J Biomech 2012; 45:952-7. [PMID: 22284992 PMCID: PMC3310328 DOI: 10.1016/j.jbiomech.2012.01.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 11/10/2011] [Accepted: 01/11/2012] [Indexed: 01/09/2023]
Abstract
The purpose of this study was to create a polymer phantom mimicking the mechanical properties of soft tissues using experimental tests and rheological models. Multifrequency Magnetic Resonance Elastography (MMRE) tests were performed on the present phantom with a pneumatic driver to characterize the viscoelastic (μ, η) properties using Voigt, Maxwell, Zener and Springpot models. To optimize the MMRE protocol, the driver behavior was analyzed with a vibrometer. Moreover, the hyperelastic properties of the phantom were determined using compressive tests and Mooney-Rivlin model. The range of frequency to be used with the round driver was found between 60 Hz and 100 Hz as it exhibits one type of vibration mode for the membrane. MRE analysis revealed an increase in the shear modulus with frequency reflecting the viscoelastic properties of the phantom showing similar characteristic of soft tissues. Rheological results demonstrated that Springpot model better revealed the viscoelastic properties (μ=3.45 kPa, η=6.17 Pas) of the phantom and the Mooney-Rivlin coefficients were C(10)=1.09.10(-2) MPa and C(01)=-8.96.10(-3) MPa corresponding to μ=3.95 kPa. These studies suggest that the phantom, mimicking soft tissue, could be used for preliminary MRE tests to identify the optimal parameters necessary for in vivo investigations. Further developments of the phantom may allow clinicians to more accurately mimic healthy and pathological soft tissues using MRE.
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Affiliation(s)
- Gwladys E. Leclerc
- Université de Technologie de Compiègne, UMR CNRS 6600, BioMécanique etBioIngénierie, France
| | - Laetitia Debernard
- Université de Technologie de Compiègne, UMR CNRS 6600, BioMécanique etBioIngénierie, France
| | - Félix Foucart
- Université de Technologie de Compiègne, UMR CNRS 6253, Laboratoire Roberval de Mécanique, France
| | | | - Kay M. Pelletier
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | | | - Richard Ehman
- Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | | | - Sabine F. Bensamoun
- Université de Technologie de Compiègne, UMR CNRS 6600, BioMécanique etBioIngénierie, France
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19
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Akagi R, Chino K, Dohi M, Takahashi H. Relationships between muscle size and hardness of the medial gastrocnemius at different ankle joint angles in young men. Acta Radiol 2012; 53:307-11. [PMID: 22302209 DOI: 10.1258/ar.2011.110481] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Measurement of muscle hardness is important for objective evaluation of the muscle condition. Muscle hardness may be related to muscle size, but this relationship has not yet been examined. PURPOSE To examine the relationship between the size and hardness of the medial gastrocnemius muscle (MG) at different ankle joint angles. MATERIAL AND METHODS Twelve young male subjects comprised the present study. Muscle thickness of the right MG (MT(MG)) was measured by ultrasonography as an index of muscle size. The MT(MG) was determined at 30% of the lower leg length from the popliteal crease to the lateral malleolus. At the same site, muscle hardness of the right MG (MH(MG)) was measured with ultrasound real-time tissue elastography. Both measurements were taken while each subject was instructed to lie in a prone position on a test bench. The right ankle was secured to a handmade apparatus by a non-elastic belt, with the hip and knee joints fully extended and the ankle positioned at +30°, 0° and -20° (0°: neutral position, positive values indicating plantar flexion). RESULTS There were no significant differences in the MT(MG) among the ankle joint angles whereas the MH(MG) significantly increased as the ankle was moved from plantar flexion to dorsiflexion. As a result, there was a difference in the MT(MG)-MH(MG) relationship between the angles. The MT(MG) significantly correlated with the MH(MG) only at +30° (r = 0.635, P < 0.05) where passive torque around the ankle has been shown to be near zero in previous studies. CONCLUSION The hardness of the relaxed MG with no passive tension appears to depend on its size.
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Affiliation(s)
- Ryota Akagi
- Department of Sports Sciences, Japan Institute of Sports Sciences, Tokyo
| | - Kentaro Chino
- Department of Life Sciences (Sports Sciences), Graduate School of Arts and Sciences, The University of Tokyo, Tokyo
| | - Michiko Dohi
- Department of Sports Medicine, Japan Institute of Sports Sciences, Tokyo, Japan
| | - Hideyuki Takahashi
- Department of Sports Sciences, Japan Institute of Sports Sciences, Tokyo
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Lacourpaille L, Hug F, Bouillard K, Hogrel JY, Nordez A. Supersonic shear imaging provides a reliable measurement of resting muscle shear elastic modulus. Physiol Meas 2012; 33:N19-28. [PMID: 22370174 DOI: 10.1088/0967-3334/33/3/n19] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of the present study was to assess the reliability of shear elastic modulus measurements performed using supersonic shear imaging (SSI) in nine resting muscles (i.e. gastrocnemius medialis, tibialis anterior, vastus lateralis, rectus femoris, triceps brachii, biceps brachii, brachioradialis, adductor pollicis obliquus and abductor digiti minimi) of different architectures and typologies. Thirty healthy subjects were randomly assigned to the intra-session reliability (n = 20), inter-day reliability (n = 21) and the inter-observer reliability (n = 16) experiments. Muscle shear elastic modulus ranged from 2.99 (gastrocnemius medialis) to 4.50 kPa (adductor digiti minimi and tibialis anterior). On the whole, very good reliability was observed, with a coefficient of variation (CV) ranging from 4.6% to 8%, except for the inter-operator reliability of adductor pollicis obliquus (CV = 11.5%). The intraclass correlation coefficients were good (0.871 ± 0.045 for the intra-session reliability, 0.815 ± 0.065 for the inter-day reliability and 0.709 ± 0.141 for the inter-observer reliability). Both the reliability and the ease of use of SSI make it a potentially interesting technique that would be of benefit to fundamental, applied and clinical research projects that need an accurate assessment of muscle mechanical properties.
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Affiliation(s)
- Lilian Lacourpaille
- EA 4334 Motricité, Interactions, Performance, Université de Nantes, Nantes, France
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21
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Yanagisawa O, Niitsu M, Kurihara T, Fukubayashi T. Evaluation of human muscle hardness after dynamic exercise with ultrasound real-time tissue elastography: a feasibility study. Clin Radiol 2011; 66:815-9. [PMID: 21529793 DOI: 10.1016/j.crad.2011.03.012] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 02/11/2011] [Accepted: 03/18/2011] [Indexed: 12/21/2022]
Abstract
AIM To assess the feasibility of ultrasound real-time tissue elastography (RTE) for measuring exercise-induced changes in muscle hardness and to compare the findings of RTE with those of a tissue hardness meter for semi-quantitative assessment of the hardness of exercised muscles. MATERIALS AND METHODS Nine male participants performed an arm-curl exercise. RTE measurements were performed by manually applying repetitive compression with the transducer on the scan position before exercise, immediately after exercise, and at 30 min after exercise; strain ratios between muscle and a reference material (hydrogel) were calculated (muscle strain/material strain). A tissue hardness meter was also used to evaluate muscle hardness. The intraclass correlation coefficients (ICCs) for the three repeated measurements at each measurement time were calculated to evaluate the intra-observer reproducibility of each technique. RESULTS Immediately after exercise, the strain ratio and the value obtained using the tissue hardness meter significantly decreased (from 1.65 to 1.35) and increased (from 51.8 to 54.3), respectively. Both parameters returned to their pre-exercise value 30 min after exercise. The ICCs of the RTE (and the ICCs of the muscle hardness meter) were 0.971 (0.816) before exercise, 0.939 (0.776) immediately after exercise, and 0.959 (0.882) at 30 min after exercise. CONCLUSION Similar to the muscle hardness meter, RTE revealed the exercise-induced changes of muscle hardness semi-quantitatively. The intra-observer reproducibility of RTE was very high at each measurement time. These findings suggest that RTE is a clinically useful technique for assessing hardness of specific exercised muscles.
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Affiliation(s)
- O Yanagisawa
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan.
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22
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Kolipaka A, McGee KP, Manduca A, Anavekar N, Ehman RL, Araoz PA. In vivo assessment of MR elastography-derived effective end-diastolic myocardial stiffness under different loading conditions. J Magn Reson Imaging 2011; 33:1224-8. [PMID: 21509882 PMCID: PMC3080706 DOI: 10.1002/jmri.22531] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To compare magnetic resonance elastography (MRE) effective stiffness to end-diastolic pressure at different loading conditions to demonstrate a relationship between myocardial MRE effective stiffness and end-diastolic left ventricular (LV) pressure. MATERIALS AND METHODS MRE was performed on four pigs to measure the end-diastolic effective stiffness under different loading conditions. End-diastolic pressure was increased by infusing Dextran-40 (20% of blood volume). For each infusion of Dextran-40, end-diastolic pressure was recorded and end-diastolic effective stiffness was measured using MRE. In each pig, least-square linear regression was performed to determine the correlation between end-diastolic effective stiffness and end-diastolic LV pressure. RESULTS A linear correlation was found between end-diastolic LV pressure and end-diastolic effective stiffness with R(2) ranging from 0.73-0.9. A linear correlation with R(2) = 0.26 was found between end-diastolic LV pressure and end-diastolic effective stiffness when pooling data points from all pigs. CONCLUSION End-diastolic effective myocardial stiffness increases linearly with end-diastolic LV pressure.
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Affiliation(s)
| | | | | | - Nandan Anavekar
- Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, United States
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23
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Hannam AG. Current computational modelling trends in craniomandibular biomechanics and their clinical implications. J Oral Rehabil 2010; 38:217-34. [PMID: 20819138 DOI: 10.1111/j.1365-2842.2010.02149.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Computational models of interactions in the craniomandibular apparatus are used with increasing frequency to study biomechanics in normal and abnormal masticatory systems. Methods and assumptions in these models can be difficult to assess by those unfamiliar with current practices in this field; health professionals are often faced with evaluating the appropriateness, validity and significance of models which are perhaps more familiar to the engineering community. This selective review offers a foundation for assessing the strength and implications of a craniomandibular modelling study. It explores different models used in general science and engineering and focuses on current best practices in biomechanics. The problem of validation is considered at some length, because this is not always fully realisable in living subjects. Rigid-body, finite element and combined approaches are discussed, with examples of their application to basic and clinically relevant problems. Some advanced software platforms currently available for modelling craniomandibular systems are mentioned. Recent studies of the face, masticatory muscles, tongue, craniomandibular skeleton, temporomandibular joint, dentition and dental implants are reviewed, and the significance of non-linear and non-isotropic material properties is emphasised. The unique challenges in clinical application are discussed, and the review concludes by posing some questions which one might reasonably expect to find answered in plausible modelling studies of the masticatory apparatus.
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Affiliation(s)
- A G Hannam
- Faculty of Dentistry, Department of Oral Health Sciences, The University of British Columbia, Vancouver, BC, Canada.
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24
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Allgayer H, Ignee A, Dietrich CF. Endosonographic elastography of the anal sphincter in patients with fecal incontinence. Scand J Gastroenterol 2010; 45:30-8. [PMID: 20001748 DOI: 10.3109/00365520903383251] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE In fecal incontinence the role of elastography has not yet been evaluated. We performed a trial to further characterize the internal and external anal sphincter in patients with fecal incontinence and compared a visual assessment scale with a computerized program for quantifying elastic properties of the anal sphincter. MATERIAL AND METHODS Fifty consecutive patients with fecal incontinence were studied (n = 31 following lower anterior resection, n = 8 with Crohn's disease, n = 9 following colon surgery, n = 2 others). Elastogram color distribution within the sphincter representing elastic properties was quantified using a visual analog scale and an off-line computerized area calculation program. RESULTS The main finding was that the inner anal sphincter (IAS) differed significantly from the external anal sphincter (EAS) with regard to elastogram color distribution. There were no significant correlations with clinical and functional parameters. There was, however, a non-significant increase in the percentage of blue (hard) areas in the IAS in patients neoadjuvantly irradiated for rectal or cervical cancer compared to non-irradiated patients, which was accompanied by a significant decrease in the resting sphincter pressure (p < 0.009). CONCLUSIONS The IAS, a smooth muscle, and the EAS, a striated muscle, have different elastogram color distributions, probably reflecting their different elastic properties. The absence of significant correlations with the major clinical and functional parameters suggests that in routine clinical practice ultrasound real-time elastography may not yield additional information in patients with fecal incontinence. There may be exceptions, particularly in irradiated patients.
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Affiliation(s)
- H Allgayer
- Department of Gastroenterology and Metabolism, Rehaklinik Ob der Tauber, Reha Zentren Baden-Württemberg, Germany
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Magnetic resonance elastography: a general overview of its current and future applications in brain imaging. Neurosurg Rev 2010; 33:137-45; discussion 145. [PMID: 20195674 DOI: 10.1007/s10143-010-0249-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 01/12/2010] [Accepted: 01/20/2010] [Indexed: 12/14/2022]
Abstract
Magnetic resonance elastography (MRE) has been developed over the last few years as a non-invasive means of evaluating the elasticity of biological tissues. The presence of the skull has always prevented semeiotic palpation of the brain, but MRE now offers the possibility of "palpating by imaging" in order to detect brain consistency under physiological and pathological conditions. The aim of this article is to review the current state-of-the-art of MRE imaging and discuss its possible future diagnostic applications in neuroscience.
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Namani R, Wood MD, Sakiyama-Elbert SE, Bayly PV. Anisotropic mechanical properties of magnetically aligned fibrin gels measured by magnetic resonance elastography. J Biomech 2009; 42:2047-53. [PMID: 19656516 DOI: 10.1016/j.jbiomech.2009.06.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 06/03/2009] [Accepted: 06/03/2009] [Indexed: 10/20/2022]
Abstract
The anisotropic mechanical properties of magnetically aligned fibrin gels were measured by magnetic resonance elastography (MRE) and by a standard mechanical test: unconfined compression. Soft anisotropic biomaterials are notoriously difficult to characterize, especially in vivo. MRE is well-suited for efficient, non-invasive, and non-destructive assessment of shear modulus. Direction-dependent differences in shear modulus were found to be statistically significant for gels polymerized at magnetic fields of 11.7 and 4.7 T compared to control gels. Mechanical anisotropy was greater in the gels polymerized at the higher magnetic field. These observations were consistent with results from unconfined compression tests. Analysis of confocal microscopy images of gels showed measurable alignment of fibrils in gels polymerized at 11.7 T. This study provides direct, quantitative measurements of the anisotropy in mechanical properties that accompanies fibril alignment in fibrin gels.
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Affiliation(s)
- Ravi Namani
- Department of Mechanical, Aerospace & Structural Engineering, Washington University in St. Louis, MO 63130, USA.
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