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Progressive supranuclear palsy and idiopathic Parkinson’s disease are associated with local reduction of in vivo brain viscoelasticity. Eur Radiol 2018; 28:3347-3354. [DOI: 10.1007/s00330-017-5269-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/27/2017] [Accepted: 12/20/2017] [Indexed: 10/18/2022]
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Hetzer S, Birr P, Fehlner A, Hirsch S, Dittmann F, Barnhill E, Braun J, Sack I. Perfusion alters stiffness of deep gray matter. J Cereb Blood Flow Metab 2018; 38:116-125. [PMID: 28151092 PMCID: PMC5757437 DOI: 10.1177/0271678x17691530] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Viscoelastic properties of the brain reflect tissue architecture at multiple length scales. However, little is known about the relation between vital tissue functions, such as perfusion, and the macroscopic mechanical properties of cerebral tissue. In this study, arterial spin labelling is paired with magnetic resonance elastography to investigate the relationship between tissue stiffness and cerebral blood flow (CBF) in the in vivo human brain. The viscoelastic modulus, | G*|, and CBF were studied in deep gray matter (DGM) of 14 healthy male volunteers in the following sub-regions: putamen, nucleus accumbens, hippocampus, thalamus, globus pallidus, and amygdala. CBF was further normalized by vessel area data to obtain the flux rate q which is proportional to the perfusion pressure gradient. The striatum (represented by putamen and nucleus accumbens) was distinct from the other DGM regions by displaying markedly higher stiffness and perfusion values. q was a predictive marker for DGM stiffness as analyzed by linear regression | G*| = q·(4.2 ± 0.6)kPa·s + (0.80 ± 0.06)kPa ( R2 = 0.92, P = 0.006). These results suggest a high sensitivity of MRE in DGM to perfusion pressure. The distinct mechano-vascular properties of striatum tissue, as compared to the rest of DGM, may reflect elevated perfusion pressure, which could explain the well-known susceptibility of the putamen to hemorrhages.
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Affiliation(s)
- Stefan Hetzer
- 1 Berlin Center for Advanced Neuroimaging, Charité - Universitätsmedizin Berlin, Berlin, Germany.,2 Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Patric Birr
- 3 Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Andreas Fehlner
- 3 Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Sebastian Hirsch
- 4 Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Florian Dittmann
- 3 Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Eric Barnhill
- 3 Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jürgen Braun
- 4 Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ingolf Sack
- 3 Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Gerischer LM, Fehlner A, Köbe T, Prehn K, Antonenko D, Grittner U, Braun J, Sack I, Flöel A. Combining viscoelasticity, diffusivity and volume of the hippocampus for the diagnosis of Alzheimer's disease based on magnetic resonance imaging. NEUROIMAGE-CLINICAL 2017. [PMID: 29527504 PMCID: PMC5842309 DOI: 10.1016/j.nicl.2017.12.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Dementia due to Alzheimer's Disease (AD) is a neurodegenerative disease for which treatment strategies at an early stage are of great clinical importance. So far, there is still a lack of non-invasive diagnostic tools to sensitively detect AD in early stages and to predict individual disease progression. Magnetic resonance elastography (MRE) of the brain may be a promising novel tool. In this proof-of-concept study, we investigated whether multifrequency-MRE (MMRE) can detect differences in hippocampal stiffness between patients with clinical diagnosis of dementia due to AD and healthy controls (HC). Further, we analyzed if the combination of three MRI-derived parameters, i.e., hippocampal stiffness, hippocampal volume and mean diffusivity (MD), improves diagnostic accuracy. Diagnostic criteria for probable dementia due to AD were in line with the NINCDS-ADRDA criteria and were verified through history-taking (patient and informant), neuropsychological testing, routine blood results and routine MRI to exclude other medical causes of a cognitive decline. 21 AD patients and 21 HC (median age 75 years) underwent MMRE and structural MRI, from which hippocampal volume and MD were calculated. From the MMRE-images maps of the magnitude |G*| and phase angle φ of the complex shear modulus were reconstructed using multifrequency inversion. Median values of |G*| and φ were extracted within three regions of interest (hippocampus, thalamus and whole brain white matter). To test the predictive value of the main outcome parameters, we performed receiver operating characteristic (ROC) curve analyses. Hippocampal stiffness (|G*|) and viscosity (φ) were significantly lower in the patient group (both p < 0.001). ROC curve analyses showed an area under the curve (AUC) for | G*| of 0.81 [95%CI 0.68–0.94]; with sensitivity 86%, specificity 67% for cutoff at |G*| = 980 Pa) and for φ an AUC of 0.79 [95%CI 0.66–0.93]. In comparison, the AUC of MD and hippocampal volume were 0.83 [95%CI 0.71–0.95] and 0.86 [95%CI 0.74–0.97], respectively. A combined ROC curve of |G*|, MD and hippocampal volume yielded a significantly improved AUC of 0.90 [95%CI 0.81–0.99]. In conclusion, we demonstrated reduced hippocampal stiffness and reduced hippocampal viscosity, as determined by MMRE, in patients with clinical diagnosis of dementia of the AD type. Diagnostic sensitivity was further improved by the combination with two other MRI-based hippocampal parameters. These findings motivate further investigation whether MMRE can detect decreased brain stiffness already in pre-dementia stages, and whether these changes predict cognitive decline. Non-invasive methods for early detection of AD are lacking. MRE of the brain is a promising new non-invasive diagnostic tool. We demonstrate reduced hippocampal stiffness (|G*|) in AD patients. |G*| distinguishes healthy and demented with 86% sensitivity and 67% specificity. Combining hippocampal stiffness, MD and volume improved diagnostic accuracy.
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Affiliation(s)
- Lea M Gerischer
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Neurology, Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany; Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Clinical Research Center, Berlin, Germany
| | - Andreas Fehlner
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Radiology, Berlin, Germany
| | - Theresa Köbe
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Neurology, Berlin, Germany; Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Clinical Research Center, Berlin, Germany
| | - Kristin Prehn
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Neurology, Berlin, Germany; Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Clinical Research Center, Berlin, Germany
| | - Daria Antonenko
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Neurology, Berlin, Germany; Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Clinical Research Center, Berlin, Germany; University Medicine Greifswald, Department of Neurology, Greifswald, Germany
| | - Ulrike Grittner
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department for Biostatistics and Clinical Epidemiology, Berlin, Germany
| | - Jürgen Braun
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Medical Informatics, Berlin, Germany
| | - Ingolf Sack
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Radiology, Berlin, Germany
| | - Agnes Flöel
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Neurology, Berlin, Germany; Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, NeuroCure Clinical Research Center, Berlin, Germany; University Medicine Greifswald, Department of Neurology, Greifswald, Germany.
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Murphy MC, Manduca A, Trzasko JD, Glaser KJ, Huston J, Ehman RL. Artificial neural networks for stiffness estimation in magnetic resonance elastography. Magn Reson Med 2017; 80:351-360. [PMID: 29193306 DOI: 10.1002/mrm.27019] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 10/20/2017] [Accepted: 10/30/2017] [Indexed: 01/22/2023]
Abstract
PURPOSE To investigate the feasibility of using artificial neural networks to estimate stiffness from MR elastography (MRE) data. METHODS Artificial neural networks were fit using model-based training patterns to estimate stiffness from images of displacement using a patch size of ∼1 cm in each dimension. These neural network inversions (NNIs) were then evaluated in a set of simulation experiments designed to investigate the effects of wave interference and noise on NNI accuracy. NNI was also tested in vivo, comparing NNI results against currently used methods. RESULTS In 4 simulation experiments, NNI performed as well or better than direct inversion (DI) for predicting the known stiffness of the data. Summary NNI results were also shown to be significantly correlated with DI results in the liver (R2 = 0.974) and in the brain (R2 = 0.915), and also correlated with established biological effects including fibrosis stage in the liver and age in the brain. Finally, repeatability error was lower in the brain using NNI compared to DI, and voxel-wise modeling using NNI stiffness maps detected larger effects than using DI maps with similar levels of smoothing. CONCLUSION Artificial neural networks represent a new approach to inversion of MRE data. Summary results from NNI and DI are highly correlated and both are capable of detecting biologically relevant signals. Preliminary evidence suggests that NNI stiffness estimates may be more resistant to noise than an algebraic DI approach. Taken together, these results merit future investigation into NNIs to improve the estimation of stiffness in small regions. Magn Reson Med 80:351-360, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
| | - Armando Manduca
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Kevin J Glaser
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - John Huston
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
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Yue JL, Tardieu M, Julea F, Boucneau T, Sinkus R, Pellot-Barakat C, Maître X. Acquisition and reconstruction conditions in silico for accurate and precise magnetic resonance elastography. ACTA ACUST UNITED AC 2017; 62:8655-8670. [DOI: 10.1088/1361-6560/aa9164] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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56
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Murphy MC, Huston J, Ehman RL. MR elastography of the brain and its application in neurological diseases. Neuroimage 2017; 187:176-183. [PMID: 28993232 DOI: 10.1016/j.neuroimage.2017.10.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 12/13/2022] Open
Abstract
Magnetic resonance elastography (MRE) is an imaging technique for noninvasively and quantitatively assessing tissue stiffness, akin to palpation. MRE is further able assess the mechanical properties of tissues that cannot be reached by hand including the brain. The technique is a three-step process beginning with the introduction of shear waves into the tissue of interest by applying an external vibration. Next, the resulting motion is imaged using a phase-contrast MR pulse sequence with motion encoding gradients that are synchronized to the vibration. Finally, the measured displacement images are mathematically inverted to compute a map of the estimated stiffness. In the brain, the technique has demonstrated strong test-retest repeatability with typical errors of 1% for measuring global stiffness, 2% for measuring stiffness in the lobes of the brain, and 3-7% for measuring stiffness in subcortical gray matter. In healthy volunteers, multiple studies have confirmed that stiffness decreases with age, while more recent studies have demonstrated a strong relationship between viscoelasticity and behavioral performance. Furthermore, several studies have demonstrated the sensitivity of brain stiffness to neurodegeneration, as stiffness has been shown to decrease in multiple sclerosis and in several forms of dementia. Moreover, the spatial pattern of stiffness changes varies among these different classes of dementia. Finally, MRE is a promising tool for the preoperative assessment of intracranial tumors, as it can measure both tumor consistency and adherence to surrounding tissues. These factors are important predictors of surgical difficulty. In brief, MRE demonstrates potential value in a number of neurological diseases. However, significant opportunity remains to further refine the technique and better understand the underlying physiology.
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Affiliation(s)
- Matthew C Murphy
- Department of Radiology, Mayo Clinic, Rochester, MN, United States.
| | - John Huston
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
| | - Richard L Ehman
- Department of Radiology, Mayo Clinic, Rochester, MN, United States
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57
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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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58
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Johnson CL, Telzer EH. Magnetic resonance elastography for examining developmental changes in the mechanical properties of the brain. Dev Cogn Neurosci 2017; 33:176-181. [PMID: 29239832 PMCID: PMC5832528 DOI: 10.1016/j.dcn.2017.08.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 08/19/2017] [Accepted: 08/28/2017] [Indexed: 12/13/2022] Open
Abstract
Magnetic resonance elastography (MRE) is a quantitative imaging technique for noninvasively characterizing tissue mechanical properties, and has recently emerged as a valuable tool for neuroimaging. The measured mechanical properties reflect the microstructural composition and organization of neural tissue, and have shown significant effects in many neurological conditions and normal, healthy aging, and evidence has emerged supporting novel relationships between mechanical structure and cognitive function. The sensitivity of MRE to brain structure, function, and health make it an ideal technique for studying the developing brain; however, brain MRE studies on children and adolescents have only just begun. In this article, we review brain MRE and its findings, discuss its potential role in developmental neuroimaging, and provide suggestions for researchers interested in adopting this technique.
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Affiliation(s)
- Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, 150 Academy St., Newark, DE 19716, United States.
| | - Eva H Telzer
- Department of Psychology and Neuroscience, University of North Carolina, 235 E Cameron Ave, Chapel Hill, NC 27599, United States.
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59
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Hollis L, Barnhill E, Perrins M, Kennedy P, Conlisk N, Brown C, Hoskins PR, Pankaj P, Roberts N. Finite element analysis to investigate variability of MR elastography in the human thigh. Magn Reson Imaging 2017; 43:27-36. [PMID: 28669751 DOI: 10.1016/j.mri.2017.06.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 05/14/2017] [Accepted: 06/16/2017] [Indexed: 11/19/2022]
Abstract
PURPOSE To develop finite element analysis (FEA) of magnetic resonance elastography (MRE) in the human thigh and investigate inter-individual variability of measurement of muscle mechanical properties. METHODS Segmentation was performed on MRI datasets of the human thigh from 5 individuals and FEA models consisting of 12 muscles and surrounding tissue created. The same material properties were applied to each tissue type and a previously developed transient FEA method of simulating MRE using Abaqus was performed at 4 frequencies. Synthetic noise was applied to the simulated data at various levels before inversion was performed using the Elastography Software Pipeline. Maps of material properties were created and visually assessed to determine key features. The coefficient of variation (CoV) was used to assess the variability of measurements in each individual muscle and in the groups of muscles across the subjects. Mean measurements for the set of muscles were ranked in size order and compared with the expected ranking. RESULTS At noise levels of 2% the CoV in measurements of |G*| ranged from 5.3 to 21.9% and from 7.1 to 36.1% for measurements of ϕ in the individual muscles. A positive correlation (R2 value 0.80) was attained when the expected and measured |G*| ranking were compared, whilst a negative correlation (R2 value 0.43) was found for ϕ. CONCLUSIONS Created elastograms demonstrated good definition of muscle structure and were robust to noise. Variability of measurements across the 5 subjects was dramatically lower for |G*| than it was for ϕ. This large variability in ϕ measurements was attributed to artefacts.
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Affiliation(s)
- L Hollis
- University of Edinburgh, Clinical Research Imaging Centre, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom.
| | - E Barnhill
- Charité Universitatsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - M Perrins
- University of Edinburgh, Clinical Research Imaging Centre, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom
| | - P Kennedy
- Icahn School of Medicine, Mount Sinai, 1 Gustave L. Levy Place, New York, United States
| | - N Conlisk
- University of Edinburgh, Centre for Cardiovascular Sciences, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom
| | - C Brown
- Research and Development, The Mentholatum Company, East Kilbride G74 5PE, United Kingdom
| | - P R Hoskins
- University of Edinburgh, Centre for Cardiovascular Sciences, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom
| | - P Pankaj
- School of Engineering, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh EH9 3JL, United Kingdom
| | - N Roberts
- University of Edinburgh, Clinical Research Imaging Centre, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom.
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60
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Apoorva F, Tian YF, Pierpont TM, Bassen DM, Cerchietti L, Butcher JT, Weiss RS, Singh A. Award Winner in the Young Investigator Category, 2017 Society for Biomaterials Annual Meeting and Exposition, Minneapolis, MN, April 05-08, 2017: Lymph node stiffness-mimicking hydrogels regulate human B-cell lymphoma growth and cell surface receptor expr. J Biomed Mater Res A 2017; 105:1833-1844. [DOI: 10.1002/jbm.a.36031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/16/2016] [Accepted: 01/10/2017] [Indexed: 12/14/2022]
Affiliation(s)
- F.N.U. Apoorva
- Sibley School of Mechanical and Aerospace Engineering; College of Engineering, Cornell University; Ithaca New York
| | - Ye F. Tian
- Sibley School of Mechanical and Aerospace Engineering; College of Engineering, Cornell University; Ithaca New York
| | - Timothy M. Pierpont
- Department of Biomedical Sciences; College of Veterinary Medicine, Cornell University; Ithaca New York
| | - David M. Bassen
- Meinig School of Biomedical Engineering; College of Engineering, Cornell University; Ithaca New York
| | - Leandro Cerchietti
- Division of Hematology and Medical Oncology; Weill Cornell Medical College of Cornell University; New York New York
| | - Jonathan T. Butcher
- Meinig School of Biomedical Engineering; College of Engineering, Cornell University; Ithaca New York
| | - Robert S. Weiss
- Department of Biomedical Sciences; College of Veterinary Medicine, Cornell University; Ithaca New York
| | - Ankur Singh
- Sibley School of Mechanical and Aerospace Engineering; College of Engineering, Cornell University; Ithaca New York
- Meinig School of Biomedical Engineering; College of Engineering, Cornell University; Ithaca New York
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Kennedy P, Macgregor LJ, Barnhill E, Johnson CL, Perrins M, Hunter A, Brown C, van Beek EJR, Roberts N. MR elastography measurement of the effect of passive warmup prior to eccentric exercise on thigh muscle mechanical properties. J Magn Reson Imaging 2017; 46:1115-1127. [PMID: 28218814 PMCID: PMC5600114 DOI: 10.1002/jmri.25642] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 01/06/2017] [Indexed: 01/19/2023] Open
Abstract
Purpose To investigate the effect of warmup by application of the thermal agent Deep Heat (DH) on muscle mechanical properties using magnetic resonance elastography (MRE) at 3T before and after exercise‐induced muscle damage (EIMD). Materials and Methods Twenty male participants performed an individualized protocol designed to induce EIMD in the quadriceps. DH was applied to the thigh in 50% of the participants before exercise. MRE, T2‐weighted MRI, maximal voluntary contraction (MVC), creatine kinase (CK) concentration, and muscle soreness were measured before and after the protocol to assess EIMD effects. Five participants were excluded: four having not experienced EIMD and one due to incidental findings. Results Total workload performed during the EIMD protocol was greater in the DH group than the control group (P < 0.03), despite no significant differences in baseline MVC (P = 0.23). Shear stiffness |G*| increased in the rectus femoris (RF) muscle in both groups (P < 0.03); however, DH was not a significant between‐group factor (P = 0.15). MVC values returned to baseline faster in the DH group (5 days) than the control group (7 days). Participants who displayed hyperintensity on T2‐weighted images had a greater stiffness increase following damage than those without: RF; 0.61 kPa vs. 0.15 kPa, P < 0.006, vastus intermedius; 0.34 kPa vs. 0.03 kPa, P = 0.06. Conclusion EIMD produces increased muscle stiffness as measured by MRE, with the change in |G*| significantly increased when T2 hyperintensity was present. DH did not affect CK concentration or soreness; however, DH participants produced greater workload during the EIMD protocol and exhibited accelerated MVC recovery. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1115–1127.
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Affiliation(s)
- Paul Kennedy
- Clinical Research Imaging Centre (CRIC), Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.,Translational and Molecular Imaging Institute (TMII), Icahn School of Medicine at Mount Sinai, New York, USA
| | - Lewis J Macgregor
- Health and Exercise Research Group, School of Sport, University of Stirling, UK
| | - Eric Barnhill
- Department of Radiological Science, Charité-Universitätsmedizin, Berlin, Germany
| | - Curtis L Johnson
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
| | - Michael Perrins
- Clinical Research Imaging Centre (CRIC), Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Angus Hunter
- Health and Exercise Research Group, School of Sport, University of Stirling, UK
| | - Colin Brown
- The Mentholatum Company Ltd, East Kilbride, Glasgow, UK
| | - Edwin J R van Beek
- Clinical Research Imaging Centre (CRIC), Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Neil Roberts
- Clinical Research Imaging Centre (CRIC), Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
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Fehlner A, Hirsch S, Weygandt M, Christophel T, Barnhill E, Kadobianskyi M, Braun J, Bernarding J, Lützkendorf R, Sack I, Hetzer S. Increasing the spatial resolution and sensitivity of magnetic resonance elastography by correcting for subject motion and susceptibility-induced image distortions. J Magn Reson Imaging 2016; 46:134-141. [DOI: 10.1002/jmri.25516] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 10/05/2016] [Indexed: 12/13/2022] Open
Affiliation(s)
- Andreas Fehlner
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Sebastian Hirsch
- Institute of Medical Informatics; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Martin Weygandt
- Berlin Center for Advanced Neuroimaging; Charité - Universitätsmedizin Berlin; Berlin Germany
- Bernstein Center for Computational Neuroscience; Berlin Germany
| | - Thomas Christophel
- Berlin Center for Advanced Neuroimaging; Charité - Universitätsmedizin Berlin; Berlin Germany
- Bernstein Center for Computational Neuroscience; Berlin Germany
| | - Eric Barnhill
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Mykola Kadobianskyi
- Berlin Center for Advanced Neuroimaging; Charité - Universitätsmedizin Berlin; Berlin Germany
- Bernstein Center for Computational Neuroscience; Berlin Germany
| | - Jürgen Braun
- Institute of Medical Informatics; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Johannes Bernarding
- Institute of Biometry and Medical Informatics; Otto-von-Guericke University; Magdeburg Germany
| | - Ralf Lützkendorf
- Institute of Biometry and Medical Informatics; Otto-von-Guericke University; Magdeburg Germany
| | - Ingolf Sack
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Stefan Hetzer
- Berlin Center for Advanced Neuroimaging; Charité - Universitätsmedizin Berlin; Berlin Germany
- Bernstein Center for Computational Neuroscience; Berlin Germany
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Dittmann F, Tzschätzsch H, Hirsch S, Barnhill E, Braun J, Sack I, Guo J. Tomoelastography of the abdomen: Tissue mechanical properties of the liver, spleen, kidney, and pancreas from single MR elastography scans at different hydration states. Magn Reson Med 2016; 78:976-983. [DOI: 10.1002/mrm.26484] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/17/2016] [Accepted: 09/07/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Florian Dittmann
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Heiko Tzschätzsch
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Sebastian Hirsch
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Eric Barnhill
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Jürgen Braun
- Department of Medical Informatics; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Ingolf Sack
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Jing Guo
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
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64
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Multifrequency Magnetic Resonance Elastography for the Assessment of Renal Allograft Function. Invest Radiol 2016; 51:591-5. [DOI: 10.1097/rli.0000000000000271] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Multifrequency magnetic resonance elastography of the brain reveals tissue degeneration in neuromyelitis optica spectrum disorder. Eur Radiol 2016; 27:2206-2215. [DOI: 10.1007/s00330-016-4561-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/01/2016] [Accepted: 08/11/2016] [Indexed: 10/21/2022]
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66
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Johnson CL, Schwarb H, D J McGarry M, Anderson AT, Huesmann GR, Sutton BP, Cohen NJ. Viscoelasticity of subcortical gray matter structures. Hum Brain Mapp 2016; 37:4221-4233. [PMID: 27401228 DOI: 10.1002/hbm.23314] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 06/25/2016] [Accepted: 07/05/2016] [Indexed: 12/11/2022] Open
Abstract
Viscoelastic mechanical properties of the brain assessed with magnetic resonance elastography (MRE) are sensitive measures of microstructural tissue health in neurodegenerative conditions. Recent efforts have targeted measurements localized to specific neuroanatomical regions differentially affected in disease. In this work, we present a method for measuring the viscoelasticity in subcortical gray matter (SGM) structures, including the amygdala, hippocampus, caudate, putamen, pallidum, and thalamus. The method is based on incorporating high spatial resolution MRE imaging (1.6 mm isotropic voxels) with a mechanical inversion scheme designed to improve local measures in pre-defined regions (soft prior regularization [SPR]). We find that in 21 healthy, young volunteers SGM structures differ from each other in viscoelasticity, quantified as the shear stiffness and damping ratio, but also differ from the global viscoelasticity of the cerebrum. Through repeated examinations on a single volunteer, we estimate the uncertainty to be between 3 and 7% for each SGM measure. Furthermore, we demonstrate that the use of specific methodological considerations-higher spatial resolution and SPR-both decrease uncertainty and increase sensitivity of the SGM measures. The proposed method allows for reliable MRE measures of SGM viscoelasticity for future studies of neurodegenerative conditions. Hum Brain Mapp 37:4221-4233, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Curtis L Johnson
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.,Department of Biomedical Engineering, University of Delaware, Newark, Delaware, 19716
| | - Hillary Schwarb
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| | - Matthew D J McGarry
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, 03755
| | - Aaron T Anderson
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.,Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| | - Graham R Huesmann
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.,Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.,Carle Neuroscience Institute, Carle Foundation Hospital, Urbana, Illinois, 61801
| | - Bradley P Sutton
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801
| | - Neal J Cohen
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801.,Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, Illinois, 61820
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67
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Barnhill E, Hollis L, Sack I, Braun J, Hoskins PR, Pankaj P, Brown C, van Beek EJR, Roberts N. Nonlinear multiscale regularisation in MR elastography: Towards fine feature mapping. Med Image Anal 2016; 35:133-145. [PMID: 27376240 DOI: 10.1016/j.media.2016.05.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/31/2016] [Accepted: 05/31/2016] [Indexed: 01/04/2023]
Abstract
Fine-featured elastograms may provide additional information of radiological interest in the context of in vivo elastography. Here a new image processing pipeline called ESP (Elastography Software Pipeline) is developed to create Magnetic Resonance Elastography (MRE) maps of viscoelastic parameters (complex modulus magnitude |G*| and loss angle ϕ) that preserve fine-scale information through nonlinear, multi-scale extensions of typical MRE post-processing techniques. METHODS A new MRE image processing pipeline was developed that incorporates wavelet-domain denoising, image-driven noise estimation, and feature detection. ESP was first validated using simulated data, including viscoelastic Finite Element Method (FEM) simulations, at multiple noise levels. ESP images were compared with MDEV pipeline images, both in the FEM models and in three ten-subject cohorts of brain, thigh, and liver acquisitions. ESP and MDEV mean values were compared to 2D local frequency estimation (LFE) mean values for the same cohorts as a benchmark. Finally, the proportion of spectral energy at fine frequencies was quantified using the Reduced Energy Ratio (RER) for both ESP and MDEV. RESULTS Blind estimates of added noise (σ) were within 5.3% ± 2.6% of prescribed, and the same technique estimated σ in the in vivo cohorts at 1.7 ± 0.8%. A 5 × 5 × 5 truncated Gabor filter bank effectively detects local spatial frequencies at wavelengths λ ≤ 10px. For FEM inversions, mean |G*| of hard target, soft target, and background remained within 8% of prescribed up to σ=20%, and mean ϕ results were within 10%, excepting hard target ϕ, which required redrawing around a ring artefact to achieve similar accuracy. Inspection of FEM |G*| images showed some spatial distortion around hard target boundaries and inspection of ϕ images showed ring artefacts around the same target. For the in vivo cohorts, ESP results showed mean correlation of R=0.83 with MDEV and liver stiffness estimates within 7% of 2D-LFE results. Finally, ESP showed statistically significant increase in fine feature spectral energy as measured with RER for both |G*| (p<1×10-9) and ϕ (p<1×10-3). CONCLUSION Information at finer frequencies can be recovered in ESP elastograms in typical experimental conditions, however scatter- and boundary-related artefacts may cause the fine features to have inaccurate values. In in vivo cohorts, ESP delivers an increase in fine feature spectral energy, and better performance with longer wavelengths, than MDEV while showing similar stability and robustness.
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Affiliation(s)
- Eric Barnhill
- Clinical Research Imaging Centre, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
| | - Lyam Hollis
- BHF Centre for Cardiovascular Science, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
| | - Ingolf Sack
- Charité Universitätsmedizin Berlin, Charitéplatz 1,Berlin,10117 Germany.
| | - Jürgen Braun
- Charité Universitätsmedizin Berlin, Charitéplatz 1,Berlin,10117 Germany.
| | - Peter R Hoskins
- BHF Centre for Cardiovascular Science, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
| | - Pankaj Pankaj
- School of Engineering, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh, EH9 3JL, UK.
| | - Colin Brown
- Research and Development, The Mentholatum Company, East Kilbride G74 5PE, UK.
| | - Edwin J R van Beek
- Clinical Research Imaging Centre, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
| | - Neil Roberts
- Clinical Research Imaging Centre, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, EH16 4TJ, UK.
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Tzschätzsch H, Guo J, Dittmann F, Hirsch S, Barnhill E, Jöhrens K, Braun J, Sack I. Tomoelastography by multifrequency wave number recovery from time-harmonic propagating shear waves. Med Image Anal 2016; 30:1-10. [PMID: 26845371 DOI: 10.1016/j.media.2016.01.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 12/23/2015] [Accepted: 01/04/2016] [Indexed: 01/02/2023]
Abstract
Palpation is one of the most sensitive, effective diagnostic practices, motivating the quantitative and spatially resolved determination of soft tissue elasticity parameters by medical ultrasound or MRI. However, this so-called elastography often suffers from limited anatomical resolution due to noise and insufficient elastic deformation, currently precluding its use as a tomographic modality on its own. We here introduce an efficient way of processing wave images acquired by multifrequency magnetic resonance elastography (MMRE), which relies on wave number reconstruction at different harmonic frequencies followed by their amplitude-weighted averaging prior to inversion. This results in compound maps of wave speed, which reveal variations in tissue elasticity in a tomographic fashion, i.e. an unmasked, slice-wise display of anatomical details at pixel-wise resolution. The method is demonstrated using MMRE data from the literature including abdominal and pelvic organs such as the liver, spleen, uterus body and uterus cervix. Even in small regions with low wave amplitudes, such as nucleus pulposus and spinal cord, elastic parameters consistent with literature values were obtained. Overall, the proposed method provides a simple and noise-robust strategy of in-plane wave analysis of MMRE data, with a pixel-wise resolution producing superior detail to MRE direct inversion methods.
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Affiliation(s)
- Heiko Tzschätzsch
- Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Jing Guo
- Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Florian Dittmann
- Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Sebastian Hirsch
- Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Eric Barnhill
- Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Korinna Jöhrens
- Institute of Pathology, Charité - Universitätsmedizin Berlin, Germany
| | - Jürgen Braun
- Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Germany
| | - Ingolf Sack
- Department of Radiology, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
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Simultaneous measurement of hepatic and splenic stiffness using MR elastography: preliminary experience. ACTA ACUST UNITED AC 2015; 40:803-9. [PMID: 25294006 DOI: 10.1007/s00261-014-0255-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE To compare MR elastography (MRE) using a single and a dual driver excitation for the quantification of hepatic and splenic stiffness (HS and SS), and to investigate the performance of HS and SS measured with single or dual driver excitation for the detection of liver cirrhosis in subjects with liver disease. PATIENTS AND METHODS This prospective HIPAA compliant and IRB approved study involved 49 subjects who underwent MRE at 3.0T, comparing three different acquisition methods (single driver on the liver, single driver on the spleen and dual driver acoustic excitation). A Mann-Whitney test was used to assess changes in stiffness values. Bland-Altman analysis was used to compare single and dual driver configurations for each organ. Performance for detection of liver cirrhosis was assessed using ROC analysis. Pearson correlation was used to estimate the dependence of HS and SS on spleen size. RESULTS There were 40 noncirrhotic and 9 cirrhotic patients. There was good agreement between stiffness values measured with a single or a dual driver (Bland-Altman limits of agreement -14.3 % to 18.9 % and -18.1 % to 29.7 %, CV 6.4 % and 9.4 %, for HS and SS. respectively). HS and SS were higher in subjects with liver cirrhosis (p < 0.001), with excellent detection performance (AUROC range 0.87-0.93). SS correlated strongly with spleen size (r = 0.69, p < 0.001), while HS showed weak correlation (r = 0.38, p = 0.006). CONCLUSION Using a dual acoustic driver configuration, hepatic and splenic stiffness can be simultaneously estimated with good concordance with single driver measurement.
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70
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In vivo abdominal magnetic resonance elastography for the assessment of portal hypertension before and after transjugular intrahepatic portosystemic shunt implantation. Invest Radiol 2015; 50:347-51. [PMID: 25599282 DOI: 10.1097/rli.0000000000000136] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE The objective of this study was to investigate the correlation between hepatic venous pressure gradient (HVPG) and in vivo viscoelasticity of the liver and spleen before and after transjugular intrahepatic portosystemic shunt (TIPS) implantation. MATERIALS AND METHODS Ten patients with portal hypertension were examined twice by 3-dimensional multifrequency magnetic resonance elastography as well as prior and subsequent TIPS intervention; HVPG was also measured during TIPS placement. Five harmonic vibrations (25-60 Hz) were transferred to the abdominal region and recorded for the reconstruction of 2 viscoelastic constants, |G*| and φ, corresponding to the magnitude and the phase angle of the complex shear modulus G* of the liver and spleen. RESULTS All patients had cirrhosis, yielding high |G*| values in the liver (8.34 ± 2.18 kPa) and spleen (8.44 ± 1.36 kPa). In both organs, a decrease of |G*| after TIPS placement was observed (liver: 8.34 ± 2.18 kPa vs 7.02 ± 1.46 kPa, P = 0.01; spleen: 8.44 ± 1.36 kPa vs 7.06 ± 1.32 kPa, P = 0.01), whereas φ was insensitive to TIPS. Relative changes in |G*| of the spleen were correlated with the relative change of HVPG (R² = 0.659, P = 0.013). CONCLUSIONS The observed linear correlation between spleen viscoelasticity HVPG raises the prospect of an image-based noninvasive assessment of portal pressure by magnetic resonance elastography in the follow-up of TIPS placements.
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71
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Chakouch MK, Pouletaut P, Charleux F, Bensamoun SF. Viscoelastic shear properties of in vivo thigh muscles measured by MR elastography. J Magn Reson Imaging 2015; 43:1423-33. [DOI: 10.1002/jmri.25105] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/10/2015] [Indexed: 12/25/2022] Open
Affiliation(s)
- Mashhour K. Chakouch
- Biomechanics and Bioengineering Laboratory, UMR CNRS 7338, Sorbonne University, Université de Technologie de Compiègne; Compiègne France
| | - Philippe Pouletaut
- Biomechanics and Bioengineering Laboratory, UMR CNRS 7338, Sorbonne University, Université de Technologie de Compiègne; Compiègne France
| | | | - Sabine F. Bensamoun
- Biomechanics and Bioengineering Laboratory, UMR CNRS 7338, Sorbonne University, Université de Technologie de Compiègne; Compiègne France
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72
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Pepin KM, Ehman RL, McGee KP. Magnetic resonance elastography (MRE) in cancer: Technique, analysis, and applications. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 90-91:32-48. [PMID: 26592944 PMCID: PMC4660259 DOI: 10.1016/j.pnmrs.2015.06.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 06/15/2015] [Accepted: 06/16/2015] [Indexed: 05/07/2023]
Abstract
Tissue mechanical properties are significantly altered with the development of cancer. Magnetic resonance elastography (MRE) is a noninvasive technique capable of quantifying tissue mechanical properties in vivo. This review describes the basic principles of MRE and introduces some of the many promising MRE methods that have been developed for the detection and characterization of cancer, evaluation of response to therapy, and investigation of the underlying mechanical mechanisms associated with malignancy.
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73
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Dittmann F, Hirsch S, Tzschätzsch H, Guo J, Braun J, Sack I. In vivo wideband multifrequency MR elastography of the human brain and liver. Magn Reson Med 2015; 76:1116-26. [DOI: 10.1002/mrm.26006] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 08/25/2015] [Accepted: 09/12/2015] [Indexed: 01/19/2023]
Affiliation(s)
- Florian Dittmann
- Department of Radiology; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - Sebastian Hirsch
- Institute of Medical Informatics; 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
| | - 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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74
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Chakouch MK, Charleux F, Bensamoun SF. Quantifying the Elastic Property of Nine Thigh Muscles Using Magnetic Resonance Elastography. PLoS One 2015; 10:e0138873. [PMID: 26397730 PMCID: PMC4580449 DOI: 10.1371/journal.pone.0138873] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 09/05/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Pathologies of the muscles can manifest different physiological and functional changes. To adapt treatment, it is necessary to characterize the elastic property (shear modulus) of single muscles. Previous studies have used magnetic resonance elastography (MRE), a technique based on MRI technology, to analyze the mechanical behavior of healthy and pathological muscles. The purpose of this study was to develop protocols using MRE to determine the shear modulus of nine thigh muscles at rest. METHODS Twenty-nine healthy volunteers (mean age = 26 ± 3.41 years) with no muscle abnormalities underwent MRE tests (1.5 T MRI). Five MRE protocols were developed to quantify the shear moduli of the nine following thigh muscles at rest: rectus femoris (RF), vastus medialis (VM), vastus intermedius (VI), vastus lateralis (VL), sartorius (Sr), gracilis (Gr), semimembranosus (SM), semitendinosus (ST), and biceps (BC). In addition, the shear modulus of the subcutaneous adipose tissue was analyzed. RESULTS The gracilis, sartorius, and semitendinosus muscles revealed a significantly higher shear modulus (μ_Gr = 6.15 ± 0.45 kPa, μ_ Sr = 5.15 ± 0.19 kPa, and μ_ ST = 5.32 ± 0.10 kPa, respectively) compared to other tissues (from μ_ RF = 3.91 ± 0.16 kPa to μ_VI = 4.23 ± 0.25 kPa). Subcutaneous adipose tissue had the lowest value (μ_adipose tissue = 3.04 ± 0.12 kPa) of all the tissues tested. CONCLUSION The different elasticities measured between the tissues may be due to variations in the muscles' physiological and architectural compositions. Thus, the present protocol could be applied to injured muscles to identify their behavior of elastic property. Previous studies on muscle pathology found that quantification of the shear modulus could be used as a clinical protocol to identify pathological muscles and to follow-up effects of treatments and therapies. These data could also be used for modelling purposes.
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Affiliation(s)
- Mashhour K. Chakouch
- Biomechanics and Bioengineering Laboratory, UMR CNRS 7338, Sorbonne University, Université de Technologie de Compiègne, Compiègne, France
| | | | - Sabine F. Bensamoun
- Biomechanics and Bioengineering Laboratory, UMR CNRS 7338, Sorbonne University, Université de Technologie de Compiègne, Compiègne, France
- * E-mail:
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Purwada A, Jaiswal MK, Ahn H, Nojima T, Kitamura D, Gaharwar AK, Cerchietti L, Singh A. Ex vivo engineered immune organoids for controlled germinal center reactions. Biomaterials 2015; 63:24-34. [PMID: 26072995 DOI: 10.1016/j.biomaterials.2015.06.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 06/01/2015] [Indexed: 01/15/2023]
Abstract
Ex vivo engineered three-dimensional organotypic cultures have enabled the real-time study and control of biological functioning of mammalian tissues. Organs of broad interest where its architectural, cellular, and molecular complexity has prevented progress in ex vivo engineering are the secondary immune organs. Ex vivo immune organs can enable mechanistic understanding of the immune system and more importantly, accelerate the translation of immunotherapies as well as a deeper understanding of the mechanisms that lead to their malignant transformation into a variety of B and T cell malignancies. However, till date, no modular ex vivo immune organ has been developed with an ability to control the rate of immune reaction through tunable design parameter. Here we describe a B cell follicle organoid made of nanocomposite biomaterials, which recapitulates the anatomical microenvironment of a lymphoid tissue that provides the basis to induce an accelerated germinal center (GC) reaction by continuously providing extracellular matrix (ECM) and cell-cell signals to naïve B cells. Compared to existing co-cultures, immune organoids provide a control over primary B cell proliferation with ∼100-fold higher and rapid differentiation to the GC phenotype with robust antibody class switching.
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Affiliation(s)
- Alberto Purwada
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Manish K Jaiswal
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Haelee Ahn
- Division of Hematology and Medical Oncology, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
| | - Takuya Nojima
- Division of Molecular Biology, Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Chiba 278-0022, Japan
| | - Daisuke Kitamura
- Division of Molecular Biology, Research Institute for Biomedical Sciences (RIBS), Tokyo University of Science, Noda, Chiba 278-0022, Japan
| | - Akhilesh K Gaharwar
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; Department of Materials Science & Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Leandro Cerchietti
- Division of Hematology and Medical Oncology, Weill Cornell Medical College of Cornell University, New York, NY 10065, USA
| | - Ankur Singh
- Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14853, USA.
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Tzschätzsch H, Ipek-Ugay S, Trong MN, Guo J, Eggers J, Gentz E, Fischer T, Schultz M, Braun J, Sack I. Multifrequency time-harmonic elastography for the measurement of liver viscoelasticity in large tissue windows. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:724-733. [PMID: 25638319 DOI: 10.1016/j.ultrasmedbio.2014.11.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 09/30/2014] [Accepted: 11/11/2014] [Indexed: 06/04/2023]
Abstract
Elastography of the liver for the non-invasive diagnosis of hepatic fibrosis is an established method. However, investigations of obese patients or patients with ascites are often limited by small and superficial elastographic windows. Therefore, multifrequency time-harmonic elastography (THE) based on time-resolved A-line ultrasound has recently been developed for measuring liver viscoelasticity in wide soft tissue windows and at greater depths. In this study, THE was integrated into a clinical B-mode scanner connected to a dedicated actuator bed driven by superimposed vibrations of 30- to 60-Hz frequencies. The resulting shear waves in the liver were captured along multiple profiles 7 to 14 cm in width and automatically processed for reconstruction of mean efficient shear wave speed and shear wave dispersion slope. This new modality was tested in healthy volunteers and 22 patients with clinically proven cirrhosis. Patients could be separated from controls by higher shear wave speeds (3.11 ± 0.64 m/s, 2.14-4.81 m/s, vs. 1.74 ± 0.10 m/s, 1.60-1.91 m/s) without significant degradation of data by high body mass index or ascites. Furthermore, the wave speed dispersion slope was significantly (p = 0.0025) lower in controls (5.2 ± 1.8 m/s/kHz) than in patients (39.1 ± 32.2 m/s/kHz). In conclusion, THE is useful for the diagnosis of cirrhosis in large tissue windows.
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Affiliation(s)
- Heiko Tzschätzsch
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Selcan Ipek-Ugay
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | | | - Jing Guo
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jonathan Eggers
- Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Enno Gentz
- Clinic for Gastroenterology, Infectiology and Rheumatology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas Fischer
- 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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Liu Y, Yasar TK, Royston TJ. Ultra wideband (0.5-16 kHz) MR elastography for robust shear viscoelasticity model identification. Phys Med Biol 2014; 59:7717-34. [PMID: 25419651 PMCID: PMC4442071 DOI: 10.1088/0031-9155/59/24/7717] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Changes in the viscoelastic parameters of soft biological tissues often correlate with progression of disease, trauma or injury, and response to treatment. Identifying the most appropriate viscoelastic model, then estimating and monitoring the corresponding parameters of that model can improve insight into the underlying tissue structural changes. MR Elastography (MRE) provides a quantitative method of measuring tissue viscoelasticity. In a previous study by the authors (Yasar et al 2013 Magn. Reson. Med. 70 479-89), a silicone-based phantom material was examined over the frequency range of 200 Hz-7.75 kHz using MRE, an unprecedented bandwidth at that time. Six viscoelastic models including four integer order models and two fractional order models, were fit to the wideband viscoelastic data (measured storage and loss moduli as a function of frequency). The 'fractional Voigt' model (spring and springpot in parallel) exhibited the best fit and was even able to fit the entire frequency band well when it was identified based only on a small portion of the band. This paper is an extension of that study with a wider frequency range from 500 Hz to 16 kHz. Furthermore, more fractional order viscoelastic models are added to the comparison pool. It is found that added complexity of the viscoelastic model provides only marginal improvement over the 'fractional Voigt' model. And, again, the fractional order models show significant improvement over integer order viscoelastic models that have as many or more fitting parameters.
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Affiliation(s)
- Yifei Liu
- Department of Mechanical & Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
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Streitberger KJ, Diederichs G, Guo J, Fehlner A, Hamm B, Braun J, Sack I. In vivo multifrequency magnetic resonance elastography of the human intervertebral disk. Magn Reson Med 2014; 74:1380-7. [PMID: 25359242 DOI: 10.1002/mrm.25505] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 09/30/2014] [Accepted: 10/06/2014] [Indexed: 01/07/2023]
Abstract
PURPOSE To test in vivo magnetic resonance elastography (MRE) of the human intervertebral disk (IVD). METHODS The feasibility of MRE in IVD was demonstrated in ex vivo bovine disks. Sixteen asymptomatic volunteers underwent multifrequency MRE of the lumbar spine (IVD L3/4 and L4/5, n = 32) using a posterior plate transducer connected to a loudspeaker and operated at five frequencies from 50 to 70 Hz. Full wave field data were acquired in 10 transverse slices of 2 × 2 × 2 mm(3) resolution. High-resolution maps of magnitude |G*| and phase angle φ of complex shear modulus G* were generated by multifrequency dual elasto visco (MDEV) inversion. Disk morphology was assessed by the Pfirrmann score (Pf). RESULTS Morphological Pf was 1 in 25, 2 in 3, and 3 in 4 disks. |G*| decreased with Pf by a Pearson's linear correlation coefficient of R = -0.592 (P = 0.0004), while φ remained unchanged. Group mean mechanical parameters for Pf = 1 to 3 were |G*| = 6.51 ± 1.27, 5.29 ± 0.95, 4.03 ± 0.99 kPa, and φ = 1.190 ± 0.181, 1.170 ± 0.156, 1.088 ± 0.084 rad, respectively (p[Pf1-Pf3] < 0.001). The variability of mechanical parameters in one volunteer including diurnal changes was approximately 11%. CONCLUSION Multifrequency MRE with MDEV inversion allows measurement of in vivo mechanical properties of IVDs and may provide additional information in disc degeneration beyond standard morphological changes.
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Affiliation(s)
| | - Gerd Diederichs
- Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jing Guo
- Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Andreas Fehlner
- Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Bernd Hamm
- 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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79
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Streitberger KJ, Reiss-Zimmermann M, Freimann FB, Bayerl S, Guo J, Arlt F, Wuerfel J, Braun J, Hoffmann KT, Sack I. High-resolution mechanical imaging of glioblastoma by multifrequency magnetic resonance elastography. PLoS One 2014; 9:e110588. [PMID: 25338072 PMCID: PMC4206430 DOI: 10.1371/journal.pone.0110588] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 09/17/2014] [Indexed: 12/14/2022] Open
Abstract
Objective To generate high-resolution maps of the viscoelastic properties of human brain parenchyma for presurgical quantitative assessment in glioblastoma (GB). Methods Twenty-two GB patients underwent routine presurgical work-up supplemented by additional multifrequency magnetic resonance elastography. Two three-dimensional viscoelastic parameter maps, magnitude |G*|, and phase angle φ of the complex shear modulus were reconstructed by inversion of full wave field data in 2-mm isotropic resolution at seven harmonic drive frequencies ranging from 30 to 60 Hz. Results Mechanical brain maps confirmed that GB are composed of stiff and soft compartments, resulting in high intratumor heterogeneity. GB could be easily differentiated from healthy reference tissue by their reduced viscous behavior quantified by φ (0.37±0.08 vs. 0.58±0.07). |G*|, which in solids more relates to the material's stiffness, was significantly reduced in GB with a mean value of 1.32±0.26 kPa compared to 1.54±0.27 kPa in healthy tissue (P = 0.001). However, some GB (5 of 22) showed increased stiffness. Conclusion GB are generally less viscous and softer than healthy brain parenchyma. Unrelated to the morphology-based contrast of standard magnetic resonance imaging, elastography provides an entirely new neuroradiological marker and contrast related to the biomechanical properties of tumors.
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Affiliation(s)
| | | | | | - Simon Bayerl
- Department of Neurosurgery, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jing Guo
- Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Felix Arlt
- Department of Neurosurgery, Universitätsmedizin Leipzig, Leipzig, Germany
| | - Jens Wuerfel
- Institute of Neuroradiology, Universitätsmedizin Göttingen, Göttingen, Germany
- NeuroCure, 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
- * E-mail:
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80
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In vivo high-resolution magnetic resonance elastography of the uterine corpus and cervix. Eur Radiol 2014; 24:3025-33. [PMID: 25038856 DOI: 10.1007/s00330-014-3305-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/10/2014] [Accepted: 07/01/2014] [Indexed: 12/14/2022]
Abstract
OBJECTIVES To apply 3D multifrequency MR elastography (3DMMRE) to the uterus and analyse the viscoelasticity of the uterine tissue in healthy volunteers considering individual variations and variations over the menstrual cycle. METHODS Sixteen healthy volunteers participated in the study, one of whom was examined 12 times over two menstrual cycles. Pelvic 3DMMRE was performed on a 1.5-T scanner with seven vibration frequencies (30-60 Hz) using a piezoelectric driver. Two mechanical parameter maps were obtained corresponding to the magnitude (|G (*) |) and the phase angle (φ) of the complex shear modulus. RESULTS On average, the uterine corpus had higher elasticity, but similar viscosity compared with the cervix, reflected by |G (*) |uterine corpus = 2.58 ± 0.52 kPa vs. |G (*) |cervix = 2.00 ± 0.34 kPa (p < 0.0001) and φ uterine corpus = 0.54 ± 0.08, φ cervix = 0.57 ± 0.12 (p = 0.428). With 2.23 ± 0.26 kPa, |G (*) | of the myometrium was lower in the secretory phase (SP) compared with that of the proliferative phase (PP, |G (*) | = 3.01 ± 0.26 kPa). For the endometrium, the value of |G (*) | in SP was 68% lower than during PP (PP, |G (*) | = 3.34 ± 0.42 kPa; SP, |G (*) | = 1.97 ± 0.34 kPa; p = 0.0061). CONCLUSION 3DMMRE produces high-resolution mechanical parameter maps of the uterus and cervix and shows sensitivity to structural and functional changes of the endometrium and myometrium during the menstrual cycle. KEY POINTS MR elastography provided for the first time spatially resolved viscoelasticity maps of uterus. Uterine corpus had a higher elasticity, but similar viscosity compared with cervix. The stiffness of both endometrium and myometrium decreases during the menstrual cycle.
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81
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Reiss-Zimmermann M, Streitberger KJ, Sack I, Braun J, Arlt F, Fritzsch D, Hoffmann KT. High Resolution Imaging of Viscoelastic Properties of Intracranial Tumours by Multi-Frequency Magnetic Resonance Elastography. Clin Neuroradiol 2014; 25:371-8. [PMID: 24916129 DOI: 10.1007/s00062-014-0311-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 04/29/2014] [Indexed: 12/24/2022]
Abstract
PURPOSE In recent years Magnetic Resonance Elastography (MRE) emerged into a clinically applicable imaging technique. It has been shown that MRE is capable of measuring global changes of the viscoelastic properties of cerebral tissue. The purpose of our study was to evaluate a spatially resolved three-dimensional multi-frequent MRE (3DMMRE) for assessment of the viscoelastic properties of intracranial tumours. METHODS A total of 27 patients (63 ± 13 years) were included. All examinations were performed on a 3.0 T scanner, using a modified phase-contrast echo planar imaging sequence. We used 7 vibration frequencies in the low acoustic range with a temporal resolution of 8 dynamics per wave cycle. Post-processing included multi-frequency dual elasto-visco (MDEV) inversion to generate high-resolution maps of the magnitude |G*| and the phase angle φ of the complex valued shear modulus. RESULTS The tumour entities included in this study were: glioblastoma (n = 11), anaplastic astrocytoma (n = 3), meningioma (n = 7), cerebral metastasis (n = 5) and intracerebral abscess formation (n = 1). Primary brain tumours and cerebral metastases were not distinguishable in terms of |G*| and φ. Glioblastoma presented the largest range of |G*| values and a trend was delineable that glioblastoma were slightly softer than WHO grade III tumours. In terms of φ, meningiomas were clearly distinguishable from all other entities. CONCLUSIONS In this pilot study, while analysing the viscoelastic constants of various intracranial tumour entities with an improved spatial resolution, it was possible to characterize intracranial tumours by their mechanical properties. We were able to clearly delineate meningiomas from intraaxial tumours, while for the latter group an overlap remains in viscoelastic terms.
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Affiliation(s)
- M Reiss-Zimmermann
- Department of Neuroradiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany.
| | - K-J Streitberger
- Department of Radiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - I Sack
- Department of Radiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - J Braun
- Department of Radiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - F Arlt
- Department of Neurosurgery, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany
| | - D Fritzsch
- Department of Neuroradiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany
| | - K-T Hoffmann
- Department of Neuroradiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany
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82
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Reiter R, Freise C, Jöhrens K, Kamphues C, Seehofer D, Stockmann M, Somasundaram R, Asbach P, Braun J, Samani A, Sack I. Wideband MRE and static mechanical indentation of human liver specimen: Sensitivity of viscoelastic constants to the alteration of tissue structure in hepatic fibrosis. J Biomech 2014; 47:1665-74. [DOI: 10.1016/j.jbiomech.2014.02.034] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/04/2014] [Accepted: 02/25/2014] [Indexed: 01/30/2023]
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83
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Tzschätzsch H, Ipek-Ugay S, Guo J, Streitberger KJ, Gentz E, Fischer T, Klaua R, Schultz M, Braun J, Sack I. In vivotime-harmonic multifrequency elastography of the human liver. Phys Med Biol 2014; 59:1641-54. [DOI: 10.1088/0031-9155/59/7/1641] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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84
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Abstract
Magnetic resonance elastography (MRE) has been successfully implemented in the assessment of diffuse liver diseases. Currently, MRE is the most accurate noninvasive technique for detection and staging of liver fibrosis with a potential to replace liver biopsy. Magnetic resonance elastography is able to differentiate isolated fatty liver disease from steatohepatitis with or without fibrosis. Potential clinical applications include the differentiation of benign and malignant focal liver masses and the assessment of treatment response in diffuse liver diseases.
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85
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Klatt D, Yasar TK, Royston TJ, Magin RL. Sample interval modulation for the simultaneous acquisition of displacement vector data in magnetic resonance elastography: theory and application. Phys Med Biol 2013; 58:8663-75. [PMID: 24256743 DOI: 10.1088/0031-9155/58/24/8663] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SampLe Interval Modulation-magnetic resonance elastography (SLIM-MRE) is introduced for simultaneously encoding all three displacement projections of a monofrequency vibration into the MR signal phase. In SLIM-MRE, the individual displacement components are observed using different sample intervals. In doing so, the components are modulated with different apparent frequencies in the MR signal phase expressed as a harmonic function of the start time of the motion encoding gradients and can thus be decomposed by applying a Fourier transform to the sampled multidirectional MR phases. In this work, the theoretical foundations of SLIM-MRE are presented and the new idea is implemented using a high field (11.7 T) vertical bore magnetic resonance imaging system on an inhomogeneous agarose gel phantom sample. The local frequency estimation-derived stiffness values were the same within the error margins for both the new SLIM-MRE method and for conventional MRE, while the number of temporally-resolved MRE experiments needed for each study was reduced from three to one. In this work, we present for the first time, monofrequency displacement data along three sensitization directions that were acquired simultaneously and stored in the same k-space.
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Affiliation(s)
- Dieter Klatt
- Department of Bioengineering, The University of Illinois at Chicago, Chicago, IL, USA
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Guo J, Hirsch S, Fehlner A, Papazoglou S, Scheel M, Braun J, Sack I. Towards an elastographic atlas of brain anatomy. PLoS One 2013; 8:e71807. [PMID: 23977148 PMCID: PMC3743755 DOI: 10.1371/journal.pone.0071807] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 07/03/2013] [Indexed: 11/18/2022] Open
Abstract
Cerebral viscoelastic constants can be measured in a noninvasive, image-based way by magnetic resonance elastography (MRE) for the detection of neurological disorders. However, MRE brain maps of viscoelastic constants are still limited by low spatial resolution. Here we introduce three-dimensional multifrequency MRE of the brain combined with a novel reconstruction algorithm based on a model-free multifrequency inversion for calculating spatially resolved viscoelastic parameter maps of the human brain corresponding to the dynamic range of shear oscillations between 30 and 60 Hz. Maps of two viscoelastic parameters, the magnitude and the phase angle of the complex shear modulus, |G*| and φ, were obtained and normalized to group templates of 23 healthy volunteers in the age range of 22 to 72 years. This atlas of the anatomy of brain mechanics reveals a significant contrast in the stiffness parameter |G*| between different anatomical regions such as white matter (WM; 1.252±0.260 kPa), the corpus callosum genu (CCG; 1.104±0.280 kPa), the thalamus (TH; 1.058±0.208 kPa) and the head of the caudate nucleus (HCN; 0.649±0.101 kPa). φ, which is sensitive to the lossy behavior of the tissue, was in the order of CCG (1.011±0.172), TH (1.037±0.173), CN (0.906±0.257) and WM (0.854±0.169). The proposed method provides the first normalized maps of brain viscoelasticity with anatomical details in subcortical regions and provides useful background data for clinical applications of cerebral MRE.
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Affiliation(s)
- Jing Guo
- Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Sebastian Hirsch
- Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Andreas Fehlner
- Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Sebastian Papazoglou
- Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Michael Scheel
- Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
| | - Juergen Braun
- Institute of Medical Informatics, Charité, Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Ingolf Sack
- Department of Radiology, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Berlin, Germany
- * E-mail:
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