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Chen G, Fu S, Chen P, Zhong S, Chen F, Qian L, Luo Z, Pan Y, Tang G, Jia Y, Huang L, Wang Y. Reduced myelin density in unmedicated major depressive disorder: An inhomogeneous magnetization transfer MRI study. J Affect Disord 2022; 300:114-120. [PMID: 34965392 DOI: 10.1016/j.jad.2021.12.111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 12/21/2021] [Accepted: 12/24/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To detect the whole-brain reduced myelin density in unmedicated patients with major depressive disorder (MDD) using the inhomogeneous magnetization transfer (ihMT) imaging technology. Compared to other technologies, the ihMT provides high specificity and sensitivity to detect myelin. METHOD In this prospective study, fifty unmedicated patients (mean age 25.36 years, 40% men) with MDD and 57 age- and sex-matched healthy controls (HCs) (mean age 25.02 years, 53% men) were recruited between January 2019 and December 2019. All participants underwent ihMT imaging, and pseudo-quantitative ihMT (qihMT) and ihMT ratio (ihMTR) were obtained. The mean values of qihMT and ihMTR extracted from the 50 WM masks (extracted from the International Consortium for Brain Mapping, ICBM-152) in each participant were compared between participants in the MDD and HCs groups. The symptoms of patients were evaluated using the 24-item Hamilton Depression Rating scale (HDRS). RESULTS Compared with the HC group, the MDD group showed significantly decreased qihMT and ihMTR values in the left inferior fronto-occipital fasciculus (IFOF) (t = -4.057, p < 0.001; t = -3.662, p < 0.001) and the left uncinate fasciculus (UF) (t = -4.776, p < 0.001; t = -3.800, p < 0.001) after Bonferroni correction. The correlation analysis displayed a significant negative correlation between qihMT values of the left IFOF and HDRS total scores in patients with MDD (r = -0.390, p = 0.012). LIMITATIONS This was a cross-sectional study with a relative small sample. CONCLUSIONS These findings suggest the reduced myelin density in the IFOF and UF in patients with MDD, which might be associated with the pathophysiology of MDD.
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Affiliation(s)
- Guanmao Chen
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Siying Fu
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Pan Chen
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Shuming Zhong
- Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou 510630, China
| | - Feng Chen
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Long Qian
- MR Research, GE Healthcare, Beijing, China
| | - Zhenye Luo
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Youling Pan
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Guixian Tang
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Yanbin Jia
- Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou 510630, China
| | - Li Huang
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China
| | - Ying Wang
- Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Institute of Molecular and Functional Imaging, Jinan University, Guangzhou 510630, China.
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2
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Geeraert BL, Lebel RM, Lebel C. A multiparametric analysis of white matter maturation during late childhood and adolescence. Hum Brain Mapp 2019; 40:4345-4356. [PMID: 31282058 DOI: 10.1002/hbm.24706] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/28/2019] [Accepted: 06/21/2019] [Indexed: 12/21/2022] Open
Abstract
White matter development has been well described using diffusion tensor imaging (DTI), but the microstructural processes driving development remain unclear due to methodological limitations. Here, using neurite orientation dispersion and density imaging (NODDI), inhomogeneous magnetization transfer (ihMT), and multicomponent driven equilibrium single-pulse observation of T1/T2 (mcDESPOT), we describe white matter development at the microstructural level in a longitudinal cohort of healthy 6-15 year olds. We evaluated age and gender-related trends in fractional anisotropy (FA), mean diffusivity (MD), neurite density index (NDI), orientation dispersion index (ODI), quantitative ihMT (qihMT), myelin volume fraction (VFm ), and g-ratio. We found age-related increases of VFm in most regions, showing ongoing myelination in vivo during late childhood and adolescence for the first time. No relationship was observed between qihMT and age, suggesting myelin volume increases are driven by increased water content. Age-related increases were observed for NDI, suggesting axonal packing is also occurring during this time. g-ratio decreased with age in the uncinate fasciculus, implying changes in communication efficiency are ongoing in this region. FA increased and MD decreased with age in most regions. Gender effects were present in the left cingulum for FA, and an age-by-gender interaction was found for MD in the left uncinate fasciculus. These findings suggest that FA and MD remain useful markers of gender-related processes, and gender differences are likely driven by factors other than myelin. We conclude that white matter development during late childhood and adolescence is driven by a combination of axonal packing and myelin volume increases.
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Affiliation(s)
- Bryce L Geeraert
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Alberta, Canada.,Alberta Children's Hospital Research Institute and the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Robert Marc Lebel
- Alberta Children's Hospital Research Institute and the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Radiology, University of Calgary, Calgary, Alberta, Canada.,GE Healthcare, Calgary, Canada
| | - Catherine Lebel
- Alberta Children's Hospital Research Institute and the Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.,Department of Radiology, University of Calgary, Calgary, Alberta, Canada
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3
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Zhang L, Chen T, Tian H, Xue H, Ren H, Li L, Fan Q, Wen B, Ren Z. Reproducibility of inhomogeneous magnetization transfer (ihMT): A test-retest, multi-site study. Magn Reson Imaging 2019; 57:243-249. [DOI: 10.1016/j.mri.2018.11.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/29/2018] [Accepted: 11/17/2018] [Indexed: 10/27/2022]
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4
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Schyboll F, Jaekel U, Petruccione F, Neeb H. Fibre-orientation dependent R 1(=1/T 1) relaxation in the brain: The role of susceptibility induced spin-lattice relaxation in the myelin water compartment. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 300:135-141. [PMID: 30743171 DOI: 10.1016/j.jmr.2019.01.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/03/2019] [Accepted: 01/23/2019] [Indexed: 06/09/2023]
Abstract
We have recently observed a dependence of the longitudinal relaxation rate, R1, on the orientation of nerve fibres with respect to the main magnetic field. A similar dependence of R2∗ is long established and can be well explained by spin-dephasing in an inhomogeneous magnetic field induced by the susceptibility shift between myelin and water protons. The current study investigates if the same effect can also explain the R1 dependence, neglecting a possible directional dependence of magnetisation transfer between solid myelin and myelin water. A molecular model of the myelin lipid bilayer was employed to simulate the susceptibility induced fields on a microscopic scale for the different nerve fibre orientations. The resulting simulated magnetic fields were used to calculate an orientation dependent relaxation offset, ΔR1, based on both first-order perturbation theory and a simulation of the spin transition probabilities. Even though both methods yielded consistent orientation dependent relaxation offsets with a distribution that resembles the experimental data, the determined ΔR1 values are too low to explain the reported R1 angular dependency. Therefore, unlike R2∗, susceptibility induced spin flips can be excluded as a dominant source for the observed R1 angular dependence.
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Affiliation(s)
- Felix Schyboll
- University of Applied Sciences Koblenz, RheinAhrCampus Remagen, Germany
| | - Uwe Jaekel
- University of Applied Sciences Koblenz, RheinAhrCampus Remagen, Germany
| | | | - Heiko Neeb
- University of Applied Sciences Koblenz, RheinAhrCampus Remagen, Germany; Institute for Medical Engineering and Information Processing - MTI Mittelrhein, University of Koblenz, Germany.
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5
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Geeraert BL, Lebel RM, Mah AC, Deoni SC, Alsop DC, Varma G, Lebel C. A comparison of inhomogeneous magnetization transfer, myelin volume fraction, and diffusion tensor imaging measures in healthy children. Neuroimage 2018; 182:343-350. [DOI: 10.1016/j.neuroimage.2017.09.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/24/2017] [Accepted: 09/08/2017] [Indexed: 12/16/2022] Open
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Does MD. Inferring brain tissue composition and microstructure via MR relaxometry. Neuroimage 2018; 182:136-148. [PMID: 29305163 DOI: 10.1016/j.neuroimage.2017.12.087] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 12/25/2017] [Accepted: 12/27/2017] [Indexed: 11/28/2022] Open
Abstract
MRI relaxometry is sensitive to a variety of tissue characteristics in a complex manner, which makes it both attractive and challenging for characterizing tissue. This article reviews the most common water proton relaxometry measures, T1, T2, and T2*, and reports on their development and current potential to probe the composition and microstructure of brain tissue. The development of these relaxometry measures is challenged by the need for suitably accurate tissue models, as well as robust acquisition and analysis methodologies. MRI relaxometry has been established as a tool for characterizing neural tissue, particular with respect to myelination, and the potential for further development exists.
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Affiliation(s)
- Mark D Does
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Electrical Engineering, Vanderbilt University, Nashville, TN, USA.
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7
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Bouhrara M, Spencer RG. Rapid simultaneous high-resolution mapping of myelin water fraction and relaxation times in human brain using BMC-mcDESPOT. Neuroimage 2016; 147:800-811. [PMID: 27729276 DOI: 10.1016/j.neuroimage.2016.09.064] [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: 04/17/2016] [Revised: 08/21/2016] [Accepted: 09/26/2016] [Indexed: 10/20/2022] Open
Abstract
A number of central nervous system (CNS) diseases exhibit changes in myelin content and magnetic resonance longitudinal, T1, and transverse, T2, relaxation times, which therefore represent important biomarkers of CNS pathology. Among the methods applied for measurement of myelin water fraction (MWF) and relaxation times, the multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) approach is of particular interest. mcDESPOT permits whole brain mapping of multicomponent T1 and T2, with data acquisition accomplished within a clinically realistic acquisition time. Unfortunately, previous studies have indicated the limited performance of mcDESPOT in the setting of the modest signal-to-noise range of high-resolution mapping, required for the depiction of small structures and to reduce partial volume effects. Recently, we showed that a new Bayesian Monte Carlo (BMC) analysis substantially improved determination of MWF from mcDESPOT imaging data. However, our previous study was limited in that it did not discuss determination of relaxation times. Here, we extend the BMC analysis to the simultaneous determination of whole-brain MWF and relaxation times using the two-component mcDESPOT signal model. Simulation analyses and in-vivo human brain studies indicate the overall greater performance of this approach compared to the stochastic region contraction (SRC) algorithm, conventionally used to derive parameter estimates from mcDESPOT data. SRC estimates of the transverse relaxation time of the long T2 fraction, T2,l, and the longitudinal relaxation time of the short T1 fraction, T1,s, clustered towards the lower and upper parameter search space limits, respectively, indicating failure of the fitting procedure. We demonstrate that this effect is absent in the BMC analysis. Our results also showed improved parameter estimation for BMC as compared to SRC for high-resolution mapping. Overall we find that the combination of BMC analysis and mcDESPOT, BMC-mcDESPOT, shows excellent performance for accurate high-resolution whole-brain mapping of MWF and bi-component transverse and longitudinal relaxation times within a clinically realistic acquisition time.
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Affiliation(s)
- Mustapha Bouhrara
- Magnetic Resonance Imaging and Spectroscopy Section, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Intramural Research Program, BRC 04B-116, 251 Bayview Boulevard, Baltimore, MD 21224, USA.
| | - Richard G Spencer
- Magnetic Resonance Imaging and Spectroscopy Section, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Intramural Research Program, BRC 04B-116, 251 Bayview Boulevard, Baltimore, MD 21224, USA.
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8
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Arshad M, Stanley JA, Raz N. Adult age differences in subcortical myelin content are consistent with protracted myelination and unrelated to diffusion tensor imaging indices. Neuroimage 2016; 143:26-39. [PMID: 27561713 DOI: 10.1016/j.neuroimage.2016.08.047] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 08/15/2016] [Accepted: 08/21/2016] [Indexed: 01/23/2023] Open
Abstract
Post mortem studies suggest protracted myelination of subcortical white matter into the middle age followed by gradual decline in the late adulthood. To date, however, establishing the proposed inverted-U pattern of age-myelin association proved difficult, as the most common method of investigating white matter, diffusion tensor imaging (DTI), usually reveals only linear associations between DTI indices and age among healthy adults. Here we use a novel method of estimating Myelin Water Fraction (MWF) based on modeling the short spin-spin (T2) relaxation component from multi-echo T2 relaxation imaging data and assess subcortical myelin content within six white matter tracts in a sample of healthy adults (N=61, age 18-84 years). Myelin content evidenced a quadratic relationship with age, in accord with the pattern observed postmortem studies. In contrast, DTI-derived indices that are frequently cited as proxies for myelination, fractional anisotropy (FA) and radial diffusivity (RD), exhibited linear or null relationships with age. Furthermore, the magnitude of age differences in MWF varied across the white matter tracts. Myelin content estimated by MWF was unrelated to FA and correlated with RD only in the splenium. These findings are consistent with the notion that myelination continues throughout the young adulthood into the middle age. The results demonstrate that single-tensor DTI cannot serve as a source of specific proxies for myelination of white matter tracts.
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Affiliation(s)
- Muzamil Arshad
- Department of Psychiatry & Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, MI, United States; Institute of Gerontology, Wayne State University, Detroit, MI, United States
| | - Jeffrey A Stanley
- Department of Psychiatry & Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Naftali Raz
- Institute of Gerontology, Wayne State University, Detroit, MI, United States; Department of Psychology, Wayne State University, Detroit, MI, United States.
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9
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Jutras JD, Wachowicz K, De Zanche N. Analytical corrections of banding artifacts in driven equilibrium single pulse observation of T2 (DESPOT2). Magn Reson Med 2015; 76:1790-1804. [PMID: 26714609 DOI: 10.1002/mrm.26074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 11/05/2015] [Accepted: 11/15/2015] [Indexed: 11/10/2022]
Abstract
PURPOSE DESPOT2 is a single-component T2 mapping technique based on bSSFP imaging. It has seen limited application because of banding artifacts and magnetization transfer (MT) effects. In this work, acquisitions are optimized to minimize MT effects, while exact and approximate analytical equations enable automatic correction of banding artifacts within the T2 maps in mere seconds. THEORY AND METHODS The technique was verified on an agar phantom at 3 tesla. The T2 resulting from four different data combination techniques was compared with the T2 from CPMG. Two comparable DESPOT2 scan protocols (short vs. long TR/TRF ) designed to minimize MT effects, were tested both in the phantom and in vivo. A third protocol was tested in the brain of 8 volunteers and analytical correction schemes were compared with DESPOT2-FM. RESULTS The T2 measurements in agar agree with CPMG within ∼7% and in vivo results agree with values reported in the literature. The approximate analytical solutions provide increased robustness to hardware imperfections and higher T2 -to-noise ratio than the exact solutions. CONCLUSION New analytical solutions enable fast and accurate whole-brain T2 mapping from previously measured T1 and B1 maps, and bSSFP images with at least two phase offsets and two flip angles (=4 datasets, 8 min scan). Magn Reson Med 76:1790-1804, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jean-David Jutras
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - Keith Wachowicz
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Nicola De Zanche
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.,Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
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10
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Bouhrara M, Spencer RG. Incorporation of nonzero echo times in the SPGR and bSSFP signal models used in mcDESPOT. Magn Reson Med 2015; 74:1227-35. [PMID: 26407635 PMCID: PMC4619140 DOI: 10.1002/mrm.25984] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 08/03/2015] [Accepted: 08/21/2015] [Indexed: 12/22/2022]
Abstract
PURPOSE To analyze the effect of neglecting nonzero echo times (TEs) in the conventional model of multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT). THEORY AND METHODS Formulations of the two-component spoiled gradient recalled echo (SPGR) and balanced steady state free precession (bSSFP) models that incorporate nonzero TE effects are presented in the context of mcDESPOT and compared with the conventionally used SPGR and bSSFP models which ignore nonzero TEs. Relative errors in derived parameter estimates from conventional mcDESPOT, omitting TE effects, are assessed using simulations over a wide range of experimental and sample parameters. RESULTS The neglect of nonzero TE leads to an overestimate of the SPGR signal and an underestimate of the bSSFP signal. These effects can introduce large errors in parameter estimates derived from conventional mcDESPOT under realistic imaging conditions. CONCLUSION SPGR and bSSFP signal models accounting for nonzero TE effects should be incorporated into quantitative mcDESPOT analyses.
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Affiliation(s)
- Mustapha Bouhrara
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Richard G. Spencer
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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11
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Zhang J, Kolind SH, Laule C, MacKay AL. How does magnetization transfer influence mcDESPOT results? Magn Reson Med 2014; 74:1327-35. [DOI: 10.1002/mrm.25520] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2014] [Revised: 10/11/2014] [Accepted: 10/16/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Jing Zhang
- UBC MRI Research Centre, Department of Radiology; University of British Columbia; Vancouver Canada
| | - Shannon H. Kolind
- Division of Neurology, Department of Medicine; University of British Columbia; Vancouver Canada
| | - Cornelia Laule
- UBC MRI Research Centre, Department of Radiology; University of British Columbia; Vancouver Canada
- Department of Pathology & Laboratory Medicine; University of British Columbia; Vancouver Canada
| | - Alex L. MacKay
- UBC MRI Research Centre, Department of Radiology; University of British Columbia; Vancouver Canada
- Department of Physics and Astronomy; University of British Columbia; Vancouver Canada
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12
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Zhang J, Kolind SH, Laule C, MacKay AL. Comparison of myelin water fraction from multiecho T2decay curve and steady-state methods. Magn Reson Med 2014; 73:223-32. [DOI: 10.1002/mrm.25125] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 11/29/2013] [Accepted: 12/18/2013] [Indexed: 12/24/2022]
Affiliation(s)
- Jing Zhang
- UBC MRI Research Centre, Department of Radiology; University of British Columbia; Vancouver BC Canada
| | - Shannon H. Kolind
- Division of Neurology, Department of Medicine; University of British Columbia; Vancouver BC Canada
| | - Cornelia Laule
- UBC MRI Research Centre, Department of Radiology; University of British Columbia; Vancouver BC Canada
- Department of Pathology & Laboratory Medicine; University of British Columbia; Vancouver BC Canada
| | - Alex L. MacKay
- UBC MRI Research Centre, Department of Radiology; University of British Columbia; Vancouver BC Canada
- Department of Physics and Astronomy; University of British Columbia; Vancouver BC Canada
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13
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Deoni SCL, Kolind SH. Investigating the stability of mcDESPOT myelin water fraction values derived using a stochastic region contraction approach. Magn Reson Med 2014; 73:161-9. [PMID: 24464472 DOI: 10.1002/mrm.25108] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/26/2013] [Accepted: 12/10/2013] [Indexed: 12/11/2022]
Abstract
PURPOSE Multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) is an alternative to established multiecho T2 -based approaches for quantifying myelin water fraction, affording increased volumetric coverage and spatial resolution. A concern with mcDESPOT, however, is the large number of model parameters that must be estimated, which may lead to nonunique solutions and sensitivity to fitting constraints. Here we explore mcDESPOT performance under different experimental conditions to better understand the method's sensitivity and reliability. METHODS To obtain parameter estimates, mcDESPOT uses a stochastic region contraction (SRC) approach to iteratively contract a predefined solution search-space around a global optimum. The sensitivity of mcDESPOT estimates to SRC boundary conditions, and tissue parameters, was examined using numerical phantoms and acquired in vivo human data. RESULTS The SRC approach is described and shown to return robust myelin water estimates in both numerical phantoms and in vivo data under a range of experimental conditions. However, care must be taken in choosing the initial SRC boundary conditions, ensuring they are broad enough to encompass the "true" solution. CONCLUSION Results suggest that under the range of conditions examined, mcDESPOT can provide stabile and precise values.
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Affiliation(s)
- Sean C L Deoni
- Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, Rhode Island, USA
| | - Shannon H Kolind
- Department of Medicine, University of British Columbia, Vancouver, Canada
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Stöcker T, Keil F, Vahedipour K, Brenner D, Pracht E, Shah NJ. MR parameter quantification with magnetization-prepared double echo steady-state (MP-DESS). Magn Reson Med 2013; 72:103-11. [PMID: 23913587 DOI: 10.1002/mrm.24901] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/12/2013] [Accepted: 07/02/2013] [Indexed: 11/09/2022]
Abstract
PURPOSE The mapping of MR relaxation times and proton density has been the subject of research in medical imaging for many years, as it offers the possibility for longitudinal investigation of disease and the correlation with related biochemical processes. The purpose of this study is to provide a fast mapping protocol, which simultaneously acquires MR relaxation times and relative proton density without compromising accuracy and precision. METHODS This work presents a novel magnetization-prepared double echo steady-state (MP-DESS) sequence, which was designed to be sensitive to parameter variations of interest, and insensitive to variations of confounding variables. It provides high sensitivity against variations of the MR relaxation times, high acquisition efficiency, and it is insensitive to off-resonance. Accurate phase graph modeling of the MP-DESS signal is used to obtain unbiased parameter estimates. RESULTS The approach is validated in phantom and in vivo measurements. A whole-brain acquisition of 1.4-mm isotropic resolution was acquired in 15 min. Comparisons to gold-standard methods suggest a mapping precision of 5% for T1 and M0 , and below 10% for T2. CONCLUSION A new quantitative imaging technique is introduced that allows fast and isotropic simultaneous MR parameter mapping of T1, T2, and M0.
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Affiliation(s)
- Tony Stöcker
- Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich, Juelich, Germany
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15
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Duyn J. MR susceptibility imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 229:198-207. [PMID: 23273840 PMCID: PMC3602381 DOI: 10.1016/j.jmr.2012.11.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 11/14/2012] [Accepted: 11/15/2012] [Indexed: 05/23/2023]
Abstract
This work reviews recent developments in the use of magnetic susceptibility contrast for human MRI, with a focus on the study of brain anatomy. The increase in susceptibility contrast with modern high field scanners has led to novel applications and insights into the sources and mechanism contributing to this contrast in brain tissues. Dedicated experiments have demonstrated that in most of healthy brain, iron and myelin dominate tissue susceptibility variations, although their relative contribution varies substantially. Local variations in these compounds can affect both amplitude and frequency of the MRI signal. In white matter, the myelin sheath introduces an anisotropic susceptibility that has distinct effects on the water compartments inside the axons, between the myelin sheath, and the axonal space, and renders their signals dependent on the angle between the axon and the magnetic field. This offers opportunities to derive tissue properties specific to these cellular compartments.
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Affiliation(s)
- Jeff Duyn
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
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16
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Kwon OI, Woo EJ, Du YP, Hwang D. A tissue-relaxation-dependent neighboring method for robust mapping of the myelin water fraction. Neuroimage 2013; 74:12-21. [PMID: 23384527 DOI: 10.1016/j.neuroimage.2013.01.064] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 01/17/2013] [Accepted: 01/23/2013] [Indexed: 10/27/2022] Open
Abstract
Quantitative assessment of the myelin content in white matter (WM) using MRI has become a useful tool for investigating myelin-related diseases, such as multiple sclerosis (MS). Myelin water fraction (MWF) maps can be estimated pixel-by-pixel by a determination of the T₂ or T₂* spectrum from signal decay measurements at each individual image pixel. However, detection of parameters from the measured decay curve, assuming a combination of smooth multi-exponential curves, results in a nonlinear and seriously ill-posed problem. In this paper, we propose a new method to obtain a stable MWF map robust to the presence of noise while sustaining sufficient resolution, which uses weighted combinations of measured decay signals in a spatially independent neighborhood to combine tissues with similar relaxation parameters. To determine optimal weighting factors, we define a spatially independent neighborhood for each pixel and a distance with respect to decay rates that effectively includes pixels with similar decay characteristics, and which therefore have similar relaxation parameters. We recover the MWF values by using optimally weighted decay curves. We use numerical simulations and in vitro and in vivo experimental brain data scanned with a multi-gradient-echo sequence to demonstrate the feasibility of our proposed algorithm and to highlight its advantages compared to the conventional method.
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Affiliation(s)
- Oh In Kwon
- Department of Mathematics, Konkuk University, Republic of Korea
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Ropele S, Langkammer C, Enzinger C, Fuchs S, Fazekas F. Relaxation time mapping in multiple sclerosis. Expert Rev Neurother 2011; 11:441-50. [PMID: 21375449 DOI: 10.1586/ern.10.129] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Several relaxation mapping techniques have been proposed to quantitatively assess disease-related brain tissue changes in multiple sclerosis. Newer developments also account for the distribution of hydrogen protons in different tissue compartments, and therefore provide markers for myelin and macromolecular content. This article will cover the broad spectrum of the pulse sequences and analysis techniques related to this topic that are currently available. Various technical and practical limitations linked with specific approaches will be discussed. These include acquisition time, accuracy and precision, radiofrequency absorption and limited coverage of the brain. Finally, the application of these techniques in the context of multiple sclerosis will be reviewed.
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Miller KL, Tijssen RHN, Stikov N, Okell TW. Steady-state MRI: methods for neuroimaging. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/iim.10.66] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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