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Al-Shaari H, Heales CJ, Fulford J. Within-participants reliability and measurement error of magnetization transfer imaging determinations within the healthy cervical spinal cord. Radiography (Lond) 2024; 30:1085-1092. [PMID: 38772065 DOI: 10.1016/j.radi.2024.04.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 04/15/2024] [Accepted: 04/28/2024] [Indexed: 05/23/2024]
Abstract
PURPOSE To assess the within-participant reliability and measurement error in the determination of MTR in the healthy human cervical spinal cord. METHODS AND MATERIALS A total of twenty healthy controls (10 male, mean ± sd age: 33.9 ± 3.5 years, 10 females, mean ± sd age: 47.5 ± 14.4 years), with no family history of any neurological disorders or a contraindication to MRI scanning were recruited over a period of two months. Each participant was scanned twice with a 3T MRI scanner using standard MTI sequences. Spinal Cord Toolbox (v5.4) was used for image post-processing. Data were first segmented and then registered to a template and then MTR was computed. The within-participant coefficients of variation (CV%), single and average within-participants intraclass correlation coefficients (ICC) and Bland-Altman plots were determined for MT values over the volume between the 2nd and 5th cervical vertebrae for the total WM and for specific WM regions: dorsal column (DC), ventral column (VC) and lateral column (LC). RESULTS MTR showed poor to excellent within-participant reliability for the total WM, DC, VC and LC with single/average ICC values of 0.03/0.06, 0.10/0.18, 0.39/0.75, and 0.001/0.002, respectively, and the CV% reported an acceptable variation with values less than 10%. The Bland-Altman plots showed good within-participant agreement between the scan-rescan values. CONCLUSION This study demonstrates that clinical trials using MTI technique are feasible and shows that quantitative MTI can monitor tissue changes in degenerative WM patients. IMPLICATIONS FOR PRACTICE MTI with its MTR index provide broad assessment of the integrity of white matter tissue and are being studied widely in brain as a diagnostic tool for the assessment of different neurological diseases.
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Affiliation(s)
- H Al-Shaari
- Faculty of Health and Life Sciences, Medical Imaging Department, University of Exeter, Exeter, UK; College of Applied Medical Sciences, Radiological Sciences Department, Najran University, Najran, 61441, Kingdom of Saudi Arabia.
| | - C J Heales
- Faculty of Health and Life Sciences, Medical Imaging Department, University of Exeter, Exeter, UK.
| | - J Fulford
- Faculty of Health and Life Sciences, Medical Imaging Department, University of Exeter, Exeter, UK.
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2
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Lawless RD, McKnight CD, O’Grady KP, Combes AJE, Rogers BP. Detecting macromolecular differences of the CSF in low disability multiple sclerosis using quantitative MT MRI at 3T. Mult Scler J Exp Transl Clin 2023; 9:20552173231211396. [PMID: 38021451 PMCID: PMC10644741 DOI: 10.1177/20552173231211396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Background Imaging investigation of cerebrospinal fluid (CSF) in multiple sclerosis (MS) is understudied. Development of noninvasive methods to detect pathological CSF changes would have a profound effect on MS diagnosis and would offer insight into MS pathophysiology and mechanisms of neurological impairment. Objective We propose magnetization transfer (MT) MRI as a tool to detect macromolecular changes in spinal CSF. Methods MT and quantitative MT (qMT) data were acquired in the cervical region in 27 people with relapsing-remitting multiple sclerosis (pwRRMS) and 38 age and sex-matched healthy controls (HCs). MT ratio (MTR), the B1, B0, and R1 corrected qMT-derived pool size ratio (PSR) were quantified in the spinal cord and CSF of each group. Results Both CSF MTR and CSF qMT-derived PSR were significantly increased in pwRRMS compared to HC (p = 0.027 and p = 0.020, respectively). CSF PSR of pwRRMS was correlated to Expanded Disability Status Scale Scores (p = 0.045, R = 0.352). Conclusion Our findings demonstrate increased CSF macromolecular content in pwRRMS and link CSF macromolecular content with clinical impairment. This highlights the potential role of CSF in processing products of demyelination.
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Affiliation(s)
- Richard D Lawless
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Colin D McKnight
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kristin P O’Grady
- Vanderbilt University 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 Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Anna JE Combes
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Baxter P Rogers
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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Baldassari LE, Wattjes MP, Cortese ICM, Gass A, Metz I, Yousry T, Reich DS, Richert N. The neuroradiology of progressive multifocal leukoencephalopathy: a clinical trial perspective. Brain 2021; 145:426-440. [PMID: 34791056 DOI: 10.1093/brain/awab419] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/29/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system caused by the JC virus, which infects white and grey matter cells and leads to irreversible demyelination and neuroaxonal damage. Brain magnetic resonance imaging (MRI), in addition to the clinical presentation and demonstration of JC virus DNA either in the CSF or by histopathology, is an important tool in the detection of PML. In clinical practice, standard MRI pulse sequences are utilized for screening, diagnosis, and monitoring of PML, but validated imaging-based outcome measures for use in prospective, interventional clinical trials for PML have yet to be established. We review the existing literature regarding the use of MRI and positron emission tomography imaging in PML and discuss the implications of PML histopathology for neuroradiology. MRI not only demonstrates the localization and extent of PML lesions, but also mirrors the tissue destruction, ongoing viral spread, and resulting inflammation. Finally, we explore the potential for imaging measures to serve as an outcome in PML clinical trials and provide recommendations for current and future imaging outcome measure development in this area.
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Affiliation(s)
- Laura E Baldassari
- Division of Neurology 2, Office of Neuroscience, Office of New Drugs, Center for Drug Evaluation and Research, United States Food and Drug Administration, Silver Spring, Maryland, 20993, USA
| | - Mike P Wattjes
- Department of Diagnostic and Interventional Neuroradiology, Hannover Medical School, 30625 Hannover, Germany
| | - Irene C M Cortese
- Neuroimmunology Clinic, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Achim Gass
- Department of Neurology/Neuroimaging, Mannheim Center of Translational Neuroscience, University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Imke Metz
- Institute of Neuropathology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Tarek Yousry
- Neuroradiological Academic Unit, UCL IoN; Lysholm Department of Neuroradiology, UCLH National Hospital for Neurology and Neurosurgery, London, UK
| | - Daniel S Reich
- Translational Neuroradiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, 20892, USA
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Magnetization Transfer Ratio of Peripheral Nerve and Skeletal Muscle : Correlation with Demographic Variables in Healthy Volunteers. Clin Neuroradiol 2021; 32:557-564. [PMID: 34374786 PMCID: PMC9187530 DOI: 10.1007/s00062-021-01067-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/06/2021] [Indexed: 11/27/2022]
Abstract
Purpose To assess the correlation of peripheral nerve and skeletal muscle magnetization transfer ratio (MTR) with demographic variables. Methods In this study 59 healthy adults evenly distributed across 6 decades (mean age 50.5 years ±17.1, 29 women) underwent magnetization transfer imaging and high-resolution T2-weighted imaging of the sciatic nerve at 3 T. Mean sciatic nerve MTR as well as MTR of biceps femoris and vastus lateralis muscles were calculated based on manual segmentation on six representative slices. Correlations of MTR with age, body height, body weight, and body mass index (BMI) were expressed by Pearson coefficients. Best predictors for nerve and muscle MTR were determined using a multiple linear regression model with forward variable selection and fivefold cross-validation. Results Sciatic nerve MTR showed significant negative correlations with age (r = −0.47, p < 0.001), BMI (r = −0.44, p < 0.001), and body weight (r = −0.36, p = 0.006) but not with body height (p = 0.55). The multiple linear regression model determined age and BMI as best predictors for nerve MTR (R2 = 0.40). The MTR values were different between nerve and muscle tissue (p < 0.0001), but similar between muscles. Muscle MTR was associated with BMI (r = −0.46, p < 0.001 and r = −0.40, p = 0.002) and body weight (r = −0.36, p = 0.005 and r = −0.28, p = 0.035). The BMI was selected as best predictor for mean muscle MTR in the multiple linear regression model (R2 = 0.26). Conclusion Peripheral nerve MTR decreases with higher age and BMI. Studies that assess peripheral nerve MTR should consider age and BMI effects. Skeletal muscle MTR is primarily associated with BMI but overall less dependent on demographic variables. Supplementary Information The online version of this article (10.1007/s00062-021-01067-5) contains supplementary material, which is available to authorized users.
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Preisner F, Behnisch R, Foesleitner O, Schwarz D, Wehrstein M, Meredig H, Friedmann-Bette B, Heiland S, Bendszus M, Kronlage M. Reliability and reproducibility of sciatic nerve magnetization transfer imaging and T2 relaxometry. Eur Radiol 2021; 31:9120-9130. [PMID: 34104997 PMCID: PMC8589742 DOI: 10.1007/s00330-021-08072-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/08/2021] [Accepted: 05/11/2021] [Indexed: 12/19/2022]
Abstract
Objectives To assess the interreader and test-retest reliability of magnetization transfer imaging (MTI) and T2 relaxometry in sciatic nerve MR neurography (MRN). Materials and methods In this prospective study, 21 healthy volunteers were examined three times on separate days by a standardized MRN protocol at 3 Tesla, consisting of an MTI sequence, a multi-echo T2 relaxometry sequence, and a high-resolution T2-weighted sequence. Magnetization transfer ratio (MTR), T2 relaxation time, and proton spin density (PSD) of the sciatic nerve were assessed by two independent observers, and both interreader and test-retest reliability for all readout parameters were reported by intraclass correlation coefficients (ICCs) and standard error of measurement (SEM). Results For the sciatic nerve, overall mean ± standard deviation MTR was 26.75 ± 3.5%, T2 was 64.54 ± 8.2 ms, and PSD was 340.93 ± 78.8. ICCs ranged between 0.81 (MTR) and 0.94 (PSD) for interreader reliability and between 0.75 (MTR) and 0.94 (PSD) for test-retest reliability. SEM for interreader reliability was 1.7% for MTR, 2.67 ms for T2, and 21.3 for PSD. SEM for test-retest reliability was 1.7% for MTR, 2.66 ms for T2, and 20.1 for PSD. Conclusions MTI and T2 relaxometry of the sciatic nerve are reliable and reproducible. The values of measurement imprecision reported here may serve as a guide for correct interpretation of quantitative MRN biomarkers in future studies. Key Points • Magnetization transfer imaging (MTI) and T2 relaxometry of the sciatic nerve are reliable and reproducible. • The imprecision that is unavoidably associated with different scans or different readers can be estimated by the here presented SEM values for the biomarkers T2, PSD, and MTR. • These values may serve as a guide for correct interpretation of quantitative MRN biomarkers in future studies and possible clinical applications. Supplementary Information The online version contains supplementary material available at 10.1007/s00330-021-08072-9.
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Affiliation(s)
- Fabian Preisner
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Rouven Behnisch
- Institute of Medical Biometry and Informatics, University of Heidelberg, Im Neuenheimer Feld 130.3, 69120, Heidelberg, Germany
| | - Olivia Foesleitner
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Daniel Schwarz
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Michaela Wehrstein
- Department of Sports Medicine (Internal Medicine VII), Medical Clinic, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Hagen Meredig
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Birgit Friedmann-Bette
- Department of Sports Medicine (Internal Medicine VII), Medical Clinic, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Sabine Heiland
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany
| | - Moritz Kronlage
- Department of Neuroradiology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany.
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Yiannakas MC, Schneider T, Yoneyama M, Aforlabi-Logoh I, Prados F, Ciccarelli O, Wheeler-Kingshott CAM. Magnetisation transfer ratio combined with magnetic resonance neurography is feasible in the proximal lumbar plexus using healthy volunteers at 3T. Sci Rep 2020; 10:14568. [PMID: 32884016 PMCID: PMC7471697 DOI: 10.1038/s41598-020-71570-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 08/14/2020] [Indexed: 12/30/2022] Open
Abstract
Magnetic resonance neurography (MRN) has been used extensively to study pathological conditions affecting the peripheral nervous system (PNS). However, tissue damage is assessed qualitatively with little information regarding the underlying pathophysiological processes involved. Magnetisation transfer ratio (MTR) is a quantitative magnetic resonance imaging method which is sensitive to tissue macromolecular content and may therefore have an important role in the study of pathologies affecting the PNS. This study explored the feasibility of obtaining reliable MTR measurements in the proximal lumbar plexus of healthy volunteers using MRN to identify and segment each lumbar segment (L2-L5) and regions (preganglionic, ganglionic and postganglionic). Reproducibility of the MTR measurements and of the segmentation method were assessed from repeated measurements (scan-rescan), and from the reanalysis of images (intra- and inter-rater assessment), by calculating the coefficient of variation (COV). In all segments combined (L2-L5), mean (± SD) MTR was 30.5 (± 2.4). Scan-rescan, intra- and inter-rater COV values were 3.2%, 4.4% and 5.3%, respectively. One-way analysis of variance revealed a statistically significant difference in MTR between the preganglionic and postganglionic regions in all lumbar segments. This pilot study in healthy volunteers demonstrates the feasibility of obtaining reliable MTR measurements in the proximal lumbar plexus, opening up the possibility of studying a broad spectrum of neurological conditions in vivo.
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Affiliation(s)
- Marios C Yiannakas
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, Queen Square House, Queen Square, London, WC1N 3BG, UK.
| | | | | | - Innocent Aforlabi-Logoh
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, Queen Square House, Queen Square, London, WC1N 3BG, UK
| | - Ferran Prados
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, Queen Square House, Queen Square, London, WC1N 3BG, UK
- Centre for Medical Image Computing, Medical Physics and Biomedical Engineering Department, University College London, London, UK
- e-Health Centre, Universitat Oberta de Catalunya, Barcelona, Spain
| | - Olga Ciccarelli
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, Queen Square House, Queen Square, London, WC1N 3BG, UK
| | - Claudia A M Wheeler-Kingshott
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, Queen Square House, Queen Square, London, WC1N 3BG, UK
- Brain MRI 3T Research Centre, IRCCS Mondino Foundation, Pavia, Italy
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
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7
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Cronin MJ, Xu J, Bagnato F, Gochberg DF, Gore JC, Dortch RD. Rapid whole-brain quantitative magnetization transfer imaging using 3D selective inversion recovery sequences. Magn Reson Imaging 2020; 68:66-74. [PMID: 32004710 PMCID: PMC8609909 DOI: 10.1016/j.mri.2020.01.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 01/04/2020] [Accepted: 01/26/2020] [Indexed: 10/25/2022]
Abstract
Selective inversion recovery (SIR) is a quantitative magnetization transfer (qMT) method that provides estimates of parameters related to myelin content in white matter, namely the macromolecular pool-size-ratio (PSR) and the spin-lattice relaxation rate of the free pool (R1f), without the need for independent estimates of ∆B0, B1+, and T1. Although the feasibility of performing SIR in the human brain has been demonstrated, the scan times reported previously were too long for whole-brain applications. In this work, we combined optimized, short-TR acquisitions, SENSE/partial-Fourier accelerations, and efficient 3D readouts (turbo spin-echo, SIR-TSE; echo-planar imaging, SIR-EPI; and turbo field echo, SIR-TFE) to obtain whole-brain data in 18, 10, and 7 min for SIR-TSE, SIR-EPI, SIR-TFE, respectively. Based on numerical simulations, all schemes provided accurate parameter estimates in large, homogenous regions; however, the shorter SIR-TFE scans underestimated focal changes in smaller lesions due to blurring. Experimental studies in healthy subjects (n = 8) yielded parameters that were consistent with literature values and repeatable across scans (coefficient of variation: PSR = 2.2-6.4%, R1f = 0.6-1.4%) for all readouts. Overall, SIR-TFE parameters exhibited the lowest variability, while SIR-EPI parameters were adversely affected by susceptibility-related image distortions. In patients with relapsing remitting multiple sclerosis (n = 2), focal changes in SIR parameters were observed in lesions using all three readouts; however, contrast was reduced in smaller lesions for SIR-TFE, which was consistent with the numerical simulations. Together, these findings demonstrate that efficient, accurate, and repeatable whole-brain SIR can be performed using 3D TFE, EPI, or TSE readouts; however, the appropriate readout should be tailored to the application.
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Affiliation(s)
- Matthew J Cronin
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America
| | - Junzhong Xu
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America; Vanderbilt University, Department of Physics and Astronomy, Nashville, TN, United States of America
| | - Francesca Bagnato
- Vanderbilt University Medical Center, Department of Neurology, Neuro-Immunology Division/Neuro-Imaging Unit, Nashville, TN, United States of America
| | - Daniel F Gochberg
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America; Vanderbilt University, Department of Physics and Astronomy, Nashville, TN, United States of America
| | - John C Gore
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America; Vanderbilt University, Department of Physics and Astronomy, Nashville, TN, United States of America; Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, United States of America
| | - Richard D Dortch
- Vanderbilt University Medical Center, Department Radiology and Radiological Sciences, Nashville, TN, United States of America; Vanderbilt University Medical Center, Institute of Imaging Science, Nashville, TN, United States of America; Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, United States of America.
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Bagnato F, Franco G, Ye F, Fan R, Commiskey P, Smith SA, Xu J, Dortch R. Selective inversion recovery quantitative magnetization transfer imaging: Toward a 3 T clinical application in multiple sclerosis. Mult Scler 2020; 26:457-467. [PMID: 30907234 PMCID: PMC7528886 DOI: 10.1177/1352458519833018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Assessing the degree of myelin injury in patients with multiple sclerosis (MS) is challenging due to the lack of magnetic resonance imaging (MRI) methods specific to myelin quantity. By measuring distinct tissue parameters from a two-pool model of the magnetization transfer (MT) effect, quantitative magnetization transfer (qMT) may yield these indices. However, due to long scan times, qMT has not been translated clinically. OBJECTIVES We aim to assess the clinical feasibility of a recently optimized selective inversion recovery (SIR) qMT and to test the hypothesis that SIR-qMT-derived metrics are informative of radiological and clinical disease-related changes in MS. METHODS A total of 18 MS patients and 9 age- and sex-matched healthy controls (HCs) underwent a 3.0 Tesla (3 T) brain MRI, including clinical scans and an optimized SIR-qMT protocol. Four subjects were re-scanned at a 2-week interval to determine inter-scan variability. RESULTS SIR-qMT measures differed between lesional and non-lesional tissue (p < 0.0001) and between normal-appearing white matter (NAWM) of patients with more advanced disability and normal white matter (WM) of HCs (p < 0.05). SIR-qMT measures were associated with lesion volumes, disease duration, and disability scores (p ⩽ 0.002). CONCLUSION SIR-qMT at 3 T is clinically feasible and predicts both radiological and clinical disease severity in MS.
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Affiliation(s)
- Francesca Bagnato
- Department of Neurology, Neuro-Immunology Division/Neuro-Imaging Unit, Vanderbilt University Medical Center (VUMC), Nashville, TN
| | - Giulia Franco
- Department of Neurology, Neuro-Immunology Division/Neuro-Imaging Unit, Vanderbilt University Medical Center (VUMC), Nashville, TN
- IRCCS Foundation Ca’ Granda Ospedale Maggiore Policlinico, Dino Ferrari Center, Neuroscience Section, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
| | - Fei Ye
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN; USA
| | - Run Fan
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN; USA
| | | | - Seth A. Smith
- Vanderbilt University Institute of Imaging Science; Nashville, TN
| | - Junzhong Xu
- Vanderbilt University Institute of Imaging Science; Nashville, TN
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN
| | - Richard Dortch
- Vanderbilt University Institute of Imaging Science; Nashville, TN
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN
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9
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Hormuth DA, Sorace AG, Virostko J, Abramson RG, Bhujwalla ZM, Enriquez-Navas P, Gillies R, Hazle JD, Mason RP, Quarles CC, Weis JA, Whisenant JG, Xu J, Yankeelov TE. Translating preclinical MRI methods to clinical oncology. J Magn Reson Imaging 2019; 50:1377-1392. [PMID: 30925001 PMCID: PMC6766430 DOI: 10.1002/jmri.26731] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 03/14/2019] [Accepted: 03/14/2019] [Indexed: 02/05/2023] Open
Abstract
The complexity of modern in vivo magnetic resonance imaging (MRI) methods in oncology has dramatically changed in the last 10 years. The field has long since moved passed its (unparalleled) ability to form images with exquisite soft-tissue contrast and morphology, allowing for the enhanced identification of primary tumors and metastatic disease. Currently, it is not uncommon to acquire images related to blood flow, cellularity, and macromolecular content in the clinical setting. The acquisition of images related to metabolism, hypoxia, pH, and tissue stiffness are also becoming common. All of these techniques have had some component of their invention, development, refinement, validation, and initial applications in the preclinical setting using in vivo animal models of cancer. In this review, we discuss the genesis of quantitative MRI methods that have been successfully translated from preclinical research and developed into clinical applications. These include methods that interrogate perfusion, diffusion, pH, hypoxia, macromolecular content, and tissue mechanical properties for improving detection, staging, and response monitoring of cancer. For each of these techniques, we summarize the 1) underlying biological mechanism(s); 2) preclinical applications; 3) available repeatability and reproducibility data; 4) clinical applications; and 5) limitations of the technique. We conclude with a discussion of lessons learned from translating MRI methods from the preclinical to clinical setting, and a presentation of four fundamental problems in cancer imaging that, if solved, would result in a profound improvement in the lives of oncology patients. Level of Evidence: 5 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1377-1392.
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Affiliation(s)
- David A. Hormuth
- Institute for Computational Engineering and Sciences,Livestrong Cancer Institutes, The University of Texas at Austin
| | - Anna G. Sorace
- Department of Biomedical Engineering, The University of Texas at Austin,Department of Diagnostic Medicine, The University of Texas at Austin,Department of Oncology, The University of Texas at Austin,Livestrong Cancer Institutes, The University of Texas at Austin
| | - John Virostko
- Department of Diagnostic Medicine, The University of Texas at Austin,Department of Oncology, The University of Texas at Austin,Livestrong Cancer Institutes, The University of Texas at Austin
| | - Richard G. Abramson
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center
| | | | - Pedro Enriquez-Navas
- Departments of Cancer Imaging and Metabolism, Cancer Physiology, The Moffitt Cancer Center
| | - Robert Gillies
- Departments of Cancer Imaging and Metabolism, Cancer Physiology, The Moffitt Cancer Center
| | - John D. Hazle
- Imaging Physics, The University of Texas M.D. Anderson Cancer Center
| | - Ralph P. Mason
- Department of Radiology, The University of Texas Southwestern Medical Center
| | - C. Chad Quarles
- Department of NeuroImaging Research, The Barrow Neurological Institute
| | - Jared A. Weis
- Department of Biomedical Engineering Wake Forest School of Medicine
| | | | - Junzhong Xu
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center,Institute of Imaging Science, Vanderbilt University Medical Center
| | - Thomas E. Yankeelov
- Institute for Computational Engineering and Sciences,Department of Biomedical Engineering, The University of Texas at Austin,Department of Diagnostic Medicine, The University of Texas at Austin,Department of Oncology, The University of Texas at Austin,Livestrong Cancer Institutes, The University of Texas at Austin
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10
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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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11
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Kinchesh P, Allen PD, Gilchrist S, Kersemans V, Lanfredini S, Thapa A, O'Neill E, Smart SC. Reduced respiratory motion artefact in constant TR multi-slice MRI of the mouse. Magn Reson Imaging 2019; 60:1-6. [PMID: 30928386 PMCID: PMC6555631 DOI: 10.1016/j.mri.2019.03.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/20/2019] [Accepted: 03/23/2019] [Indexed: 01/29/2023]
Abstract
PURPOSE Multi-slice scanning in the abdomen and thorax of small animals is compromised by the effects of respiration unless imaging and respiration are synchronised. To avoid the signal modulations that result from respiration motion and a variable TR, blocks of fully relaxed slices are typically acquired during inter-breath periods, at the cost of scan efficiency. This paper reports a conceptually simple yet effective prospective gating acquisition mode for multi-slice scanning in free breathing small animals at any fixed TR of choice with reduced sensitivity to respiratory motion. METHODS Multi-slice scan modes have been implemented in which each slice has its own specific projection or phase encode loop index counter. When a breath is registered RF pulses continue to be applied but data are not acquired, and the corresponding counters remain fixed so that the data are acquired one TR later, providing it coincides with an inter-breath period. The approach is refined to reacquire the slice data that are acquired immediately before each breath is detected. Only the data with reduced motion artefact are used in image reconstruction. The efficacy of the method is demonstrated in the RARE scan mode which is well known to be particularly useful for tumour visualization. RESULTS Validation in mice with RARE demonstrates improved stability with respect to ungated scanning where signal averaging is often used to reduce artefacts. SNR enhancement maps demonstrate the improved efficiency of the proposed method that is equivalent to at least a 2.5 fold reduction in scan time with respect to ungated signal averaging. A steady-state magnetisation transfer contrast prepared gradient echo implementation is observed to highlight tumour structure. Supplementary simulations demonstrate that only small variations in respiration rate are required to enable efficient sampling with the proposed method. CONCLUSIONS The proposed prospective gating acquisition scheme enables efficient multi-slice scanning in small animals at the optimum TR with reduced sensitivity to respiratory motion. The method is compatible with a wide range of complementary methods including non-Cartesian scan modes, partially parallel imaging, and compressed sensing. In particular, the proposed scheme reduces the need for continual close monitoring to effect operator intervention in response to respiratory rate changes, which is both difficult to maintain and precludes high throughput.
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Affiliation(s)
- Paul Kinchesh
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom.
| | - Philip D Allen
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
| | - Stuart Gilchrist
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
| | - Veerle Kersemans
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
| | - Simone Lanfredini
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
| | - Asmita Thapa
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
| | - Eric O'Neill
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
| | - Sean C Smart
- Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, United Kingdom
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Baldassari LE, Feng J, Clayton BLL, Oh SH, Sakaie K, Tesar PJ, Wang Y, Cohen JA. Developing therapeutic strategies to promote myelin repair in multiple sclerosis. Expert Rev Neurother 2019; 19:997-1013. [PMID: 31215271 DOI: 10.1080/14737175.2019.1632192] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Introduction: Approved disease-modifying therapies for multiple sclerosis (MS) lessen inflammatory disease activity that causes relapses and MRI lesions. However, chronic inflammation and demyelination lead to axonal degeneration and neuronal loss, for which there currently is no effective treatment. There has been increasing interest in developing repair-promoting strategies, but there are important unanswered questions regarding the mechanisms and appropriate methods to evaluate these treatments. Areas covered: The rationale for remyelinating agents in MS is discussed, with an overview of both myelin physiology and endogenous repair mechanisms. This is followed by a discussion of the identification and development of potential remyelinating drugs. Potential biomarkers of remyelination are reviewed, including considerations regarding measuring remyelination in clinical trials. Information and data were obtained from a search of recent literature through PubMed. Peer-reviewed original articles and review articles were included. Expert opinion: There are several obstacles to the translation of potential remyelinating agents to clinical trials, particularly uncertainty regarding the most appropriate study population and method to monitor remyelination. Refinements in clinical trial design and outcome measurement, potentially via advanced imaging techniques, are needed to optimize detection of repair in patients with MS.
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Affiliation(s)
- Laura E Baldassari
- Mellen Center for MS Treatment and Research, Cleveland Clinic , Cleveland , OH , USA
| | - Jenny Feng
- Mellen Center for MS Treatment and Research, Cleveland Clinic , Cleveland , OH , USA
| | - Benjamin L L Clayton
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine , Cleveland , OH , USA
| | - Se-Hong Oh
- Department of Biomedical Engineering, Hankuk University of Foreign Studies , Yongin , Republic of Korea
| | - Ken Sakaie
- Imaging Institute, Cleveland Clinic , Cleveland , OH , USA
| | - Paul J Tesar
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine , Cleveland , OH , USA
| | - Yanming Wang
- Department of Radiology, Case Western Reserve University School of Medicine , Cleveland , OH , USA
| | - Jeffrey A Cohen
- Mellen Center for MS Treatment and Research, Cleveland Clinic , Cleveland , OH , USA
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Combès B, Monteau L, Bannier E, Callot V, Labauge P, Ayrignac X, Carra Dallière C, Pelletier J, Maarouf A, de Seze J, Collongues N, Barillot C, Edan G, Ferré JC, Kerbrat A. Measurement of magnetization transfer ratio (MTR) from cervical spinal cord: Multicenter reproducibility and variability. J Magn Reson Imaging 2018; 49:1777-1785. [PMID: 30350328 DOI: 10.1002/jmri.26537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 09/19/2018] [Accepted: 09/20/2018] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Assessing the multicenter variability of magnetization transfer ratio (MTR) measurements in the spinal cord of healthy controls is the first step toward investigating its clinical use as a biomarker. PURPOSE To analyze the between-session, between-participant, and between-scanner variability of MTR measurements in automatically extracted regions of interest in the cervical cord of healthy controls. STUDY TYPE Control study. POPULATION Forty-four participants, distributed across five MRI scanners (all from the same manufacturer). Ten participants were scanned twice in the same scanner, and 10 others were scanned twice in two different scanners. FIELD STRENGTH/SEQUENCE 3D-gradient echo images, centered on C5, without and with magnetization transfer prepulse at 3T. ASSESSMENT We calculated the mean MTR for different vertebral levels in the whole cord (WC), as well as in the white matter and gray matter, and determined the between-session, between-participant, and between-scanner variabilities. STATISTICAL TESTS Coefficients of variation and intraclass correlations (ICCs) for the different variabilities and their associated confidence intervals. RESULTS The MTR measurements for Levels C4-C6 (near the slab center) exhibited a mean value in WC of 34.6 pu and a pooled standard deviation of 0.9 pu. The between-session coefficient of variation was estimated as 2.3% (ICC = 0.63), the between-participant coefficient as 1.6% (ICC = 0.32), and the between-scanner coefficient as 0.7% (ICC = 0.05). The resulting aggregate coefficient of variation was 2.9%, which was sufficiently low to detect an MTR reduction of 1 pu between groups of about 45 participants (Type-I error rate: 0.05; Type-II error rate: 0.10). DATA CONCLUSION The good between-scanner reproducibility and low overall variability in cervical spinal cord MTR measurements in a control population might pave the way for multicenter analyses in various neurological diseases with moderate cohort sizes. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1777-1785.
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Affiliation(s)
- Benoit Combès
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France
| | - Laureline Monteau
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France.,CHU Rennes, Radiology Department, F-35033, Rennes, France
| | - Elise Bannier
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France.,CHU Rennes, Radiology Department, F-35033, Rennes, France
| | - Virginie Callot
- AP-HM, Pôle d'imagerie médicale, Hôpital de la Timone, CEMEREM, Marseille, France.,Aix-Marseille Université, CNRS, UMR 7339, CRMBM, Marseille, France
| | | | | | | | - Jean Pelletier
- AP-HM, Pôle d'imagerie médicale, Hôpital de la Timone, CEMEREM, Marseille, France.,AP-HM, CHU Timone, Pole de Neurosciences Cliniques, Department of Neurology, Marseille, France
| | - Adil Maarouf
- AP-HM, Pôle d'imagerie médicale, Hôpital de la Timone, CEMEREM, Marseille, France.,AP-HM, CHU Timone, Pole de Neurosciences Cliniques, Department of Neurology, Marseille, France
| | - Jerome de Seze
- Strasbourg University Hospital, France; CIC Strasbourg INSERM 1434, Strasbourg, France
| | - Nicolas Collongues
- Strasbourg University Hospital, France; CIC Strasbourg INSERM 1434, Strasbourg, France
| | - Christian Barillot
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France
| | - Gilles Edan
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France.,Neurology Department, Rennes University Hospital, France
| | - Jean Christophe Ferré
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France.,CHU Rennes, Radiology Department, F-35033, Rennes, France
| | - Anne Kerbrat
- Univ Rennes, Inria, CNRS, Inserm, IRISA UMR 6074, Visages, U1128, France.,Neurology Department, Rennes University Hospital, France
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14
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15
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Bagnato F, Hametner S, Franco G, Pawate S, Sriram S, Lassmann H, Gore J, Smith SE, Dortch R. Selective Inversion Recovery Quantitative Magnetization Transfer Brain MRI at 7T: Clinical and Postmortem Validation in Multiple Sclerosis. J Neuroimaging 2018; 28:380-388. [PMID: 29676026 DOI: 10.1111/jon.12511] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/28/2018] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND AND PURPOSE An imaging biomarker of myelin integrity is an unmet need in multiple sclerosis (MS). Selective inversion recovery (SIR) quantitative magnetization transfer imaging (qMT) provides assays of myelin content in the human brain. We previously translated the SIR method to 7T and incorporated a rapid turbo field echo (TFE) readout for whole-brain imaging within clinically acceptable scan times. We herein provide histological validation and test in vivo feasibility and applicability of the SIR-TFE protocol in MS. METHODS Clinical (T1 - and T2 -weighted) and SIR-TFE MRI scans were performed at 7T in a postmortem MS brain and MRI data were acquired in 10 MS patients and 14 heathy volunteers in vivo. The following parameters were estimated from SIR data: the macromolecular-to-free water pool-size-ratio (PSR), the spin-lattice relaxation rate of water (R1f ), and the MT exchange rate (kmf ). Differences in SIR parameters across tissue types, eg, white matter lesions (WM-Ls) and normal appearing WM (NAWM) in patients, and normal white matter (NWM) in heathy volunteers were evaluated. Associations between SIR parameters and disability scores were assessed. RESULTS For postmortem scans, correspondence was observed between WM-Ls and NAWM from histology and PSR/R1f values. In vivo differences were detected for PSR, R1f , and kmf between WM-Ls and NWM (P ≤ .041). Associations were seen between WM-Ls/ NAWM PSR and disability scores (r ≤ -.671, P ≤ .048). CONCLUSIONS SIR-qMT at 7T provides sensitive, quantitative measures of myelin integrity for clinical and research applications.
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Affiliation(s)
- Francesca Bagnato
- Department of Neurology, Neuro-Immunology Division/Neuro-Imaging Unit, Vanderbilt University Medical Center, Nashville, TN
| | - Simon Hametner
- Institute of Brain Pathology, Medical University, Vienna
| | - Giulia Franco
- Department of Neurology, Neuro-Immunology Division/Neuro-Imaging Unit, Vanderbilt University Medical Center, Nashville, TN.,Department of Neurology, University Hospital Policlinico of Milan, Italy
| | - Siddharama Pawate
- Department of Neurology, Neuro-Immunology Division, Vanderbilt University Medical Center, Nashville, TN
| | - Subramaniam Sriram
- Department of Neurology, Neuro-Immunology Division, Vanderbilt University Medical Center, Nashville, TN
| | - Hans Lassmann
- Institute of Brain Pathology, Medical University, Vienna
| | - John Gore
- Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN
| | - Seth E Smith
- Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN
| | - Richard Dortch
- Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN.,Department of Biomedical Engineering, Vanderbilt University, Nashville, TN
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Dortch RD, Bagnato F, Gochberg DF, Gore JC, Smith SA. Optimization of selective inversion recovery magnetization transfer imaging for macromolecular content mapping in the human brain. Magn Reson Med 2018; 80:1824-1835. [PMID: 29573356 DOI: 10.1002/mrm.27174] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 02/01/2018] [Accepted: 02/17/2018] [Indexed: 11/11/2022]
Abstract
PURPOSE To optimize a selective inversion recovery (SIR) sequence for macromolecular content mapping in the human brain at 3.0T. THEORY AND METHODS SIR is a quantitative method for measuring magnetization transfer (qMT) that uses a low-power, on-resonance inversion pulse. This results in a biexponential recovery of free water signal that can be sampled at various inversion/predelay times (tI/ tD ) to estimate a subset of qMT parameters, including the macromolecular-to-free pool-size-ratio (PSR), the R1 of free water (R1f ), and the rate of MT exchange (kmf ). The adoption of SIR has been limited by long acquisition times (≈4 min/slice). Here, we use Cramér-Rao lower bound theory and data reduction strategies to select optimal tI /tD combinations to reduce imaging times. The schemes were experimentally validated in phantoms, and tested in healthy volunteers (N = 4) and a multiple sclerosis patient. RESULTS Two optimal sampling schemes were determined: (i) a 5-point scheme (kmf estimated) and (ii) a 4-point scheme (kmf assumed). In phantoms, the 5/4-point schemes yielded parameter estimates with similar SNRs as our previous 16-point scheme, but with 4.1/6.1-fold shorter scan times. Pair-wise comparisons between schemes did not detect significant differences for any scheme/parameter. In humans, parameter values were consistent with published values, and similar levels of precision were obtained from all schemes. Furthermore, fixing kmf reduced the sensitivity of PSR to partial-volume averaging, yielding more consistent estimates throughout the brain. CONCLUSIONS qMT parameters can be robustly estimated in ≤1 min/slice (without independent measures of ΔB0 , B1+, and T1 ) when optimized tI -tD combinations are selected.
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Affiliation(s)
- Richard D Dortch
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Francesca Bagnato
- Department of Neurology/Neuroimmunology Division/Neuroimaging Unit, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Daniel F Gochberg
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee
| | - John C Gore
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Seth A Smith
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.,Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.,Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee
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17
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Variable density magnetization transfer (vdMT) imaging for 7 T MR imaging. Neuroimage 2018; 168:242-249. [DOI: 10.1016/j.neuroimage.2016.09.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 07/06/2016] [Accepted: 09/03/2016] [Indexed: 11/21/2022] Open
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18
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Lévy S, Guertin MC, Khatibi A, Mezer A, Martinu K, Chen JI, Stikov N, Rainville P, Cohen-Adad J. Test-retest reliability of myelin imaging in the human spinal cord: Measurement errors versus region- and aging-induced variations. PLoS One 2018; 13:e0189944. [PMID: 29293550 PMCID: PMC5749716 DOI: 10.1371/journal.pone.0189944] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 12/05/2017] [Indexed: 01/06/2023] Open
Abstract
PURPOSE To implement a statistical framework for assessing the precision of several quantitative MRI metrics sensitive to myelin in the human spinal cord: T1, Magnetization Transfer Ratio (MTR), saturation imposed by an off-resonance pulse (MTsat) and Macromolecular Tissue Volume (MTV). METHODS Thirty-three healthy subjects within two age groups (young, elderly) were scanned at 3T. Among them, 16 underwent the protocol twice to assess repeatability. Statistical reliability indexes such as the Minimal Detectable Change (MDC) were compared across metrics quantified within different cervical levels and white matter (WM) sub-regions. The differences between pathways and age groups were quantified and interpreted in context of the test-retest repeatability of the measurements. RESULTS The MDC was respectively 105.7ms, 2.77%, 0.37% and 4.08% for T1, MTR, MTsat and MTV when quantified over all WM, while the standard-deviation across subjects was 70.5ms, 1.34%, 0.20% and 2.44%. Even though particular WM regions did exhibit significant differences, these differences were on the same order as test-retest errors. No significant difference was found between age groups for all metrics. CONCLUSION While T1-based metrics (T1 and MTV) exhibited better reliability than MT-based measurements (MTR and MTsat), the observed differences between subjects or WM regions were comparable to (and often smaller than) the MDC. This makes it difficult to determine if observed changes are due to variations in myelin content, or simply due to measurement error. Measurement error remains a challenge in spinal cord myelin imaging, but this study provides statistical guidelines to standardize the field and make it possible to conduct large-scale multi-center studies.
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Affiliation(s)
- Simon Lévy
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montréal, QC, Canada
| | - Marie-Claude Guertin
- Montreal Health Innovations Coordinating Center (MHICC), Montreal Heart Institute, Montreal, QC, Canada
| | - Ali Khatibi
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montréal, QC, Canada
- Psychology Department, Bilkent University, Ankara, Turkey
- Interdisciplinary program in Neuroscience, Bilkent University, Ankara, Turkey
- National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara, Turkey
| | - Aviv Mezer
- The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kristina Martinu
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montréal, QC, Canada
| | - Jen-I Chen
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montréal, QC, Canada
- Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montreal, QC, Canada
| | - Nikola Stikov
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
- Montreal Heart Institute, Montreal, QC, Canada
| | - Pierre Rainville
- Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montréal, QC, Canada
- Department of Stomatology, Faculty of Dentistry, Université de Montréal, Montreal, QC, Canada
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
- Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montreal, QC, Canada
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Sled JG. Modelling and interpretation of magnetization transfer imaging in the brain. Neuroimage 2017; 182:128-135. [PMID: 29208570 DOI: 10.1016/j.neuroimage.2017.11.065] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 11/19/2017] [Accepted: 11/29/2017] [Indexed: 01/09/2023] Open
Abstract
Magnetization transfer contrast has yielded insight into brain tissue microstructure changes across the lifespan and in a range of disorders. This progress has been aided by the development of quantitative magnetization transfer imaging techniques able to extract intrinsic properties of the tissue that are independent of the specifics of the data acquisition. While the tissue properties extracted by these techniques do not map directly onto specific cellular structures or pathological processes, a growing body of work from animal models and histopathological correlations aids the in vivo interpretation of magnetization transfer properties of tissue. This review examines the biophysical models that have been developed to describe magnetization transfer contrast in tissue as well as the experimental evidence for the biological interpretation of magnetization transfer data in health and disease.
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Affiliation(s)
- John G Sled
- Hospital for Sick Children, Mouse Imaging Centre, Toronto, Ontario, Canada; Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
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Recent Advances in Leukoaraiosis: White Matter Structural Integrity and Functional Outcomes after Acute Ischemic Stroke. Curr Cardiol Rep 2017; 18:123. [PMID: 27796861 DOI: 10.1007/s11886-016-0803-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Leukoaraiosis, a radiographic marker of cerebral small vessel disease detected on T2-weighted brain magnetic resonance imaging (MRI) as white matter hyperintensity (WMH), is a key contributor to the risk and severity of acute cerebral ischemia. Prior investigations have emphasized the pathophysiology of WMH development and progression; however, more recently, an association between WMH burden and functional outcomes after stroke has emerged. There is growing evidence that WMH represents macroscopic injury to the white matter and that the extent of WMH burden on MRI influences functional recovery in multiple domains following acute ischemic stroke (AIS). In this review, we discuss the current understanding of WMH pathogenesis and its impact on AIS and functional recovery.
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21
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Smith AK, By S, Lyttle BD, Dortch RD, Box BA, Mckeithan LJ, Thukral S, Bagnato F, Pawate S, Smith SA. Evaluating single-point quantitative magnetization transfer in the cervical spinal cord: Application to multiple sclerosis. Neuroimage Clin 2017; 16:58-65. [PMID: 28761809 PMCID: PMC5521031 DOI: 10.1016/j.nicl.2017.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 07/03/2017] [Accepted: 07/12/2017] [Indexed: 11/19/2022]
Abstract
Spinal cord (SC) damage is linked to clinical deficits in patients with multiple sclerosis (MS), however, conventional MRI methods are not specific to the underlying macromolecular tissue changes that may precede overt lesion detection. Single-point quantitative magnetization transfer (qMT) is a method that can provide high-resolution indices sensitive to underlying macromolecular composition in a clinically feasible scan time by reducing the number of MT-weighted acquisitions and utilizing a two-pool model constrained by empirically determined constants. As the single-point qMT method relies on a priori constraints, it has not been employed extensively in patients, where these constraints may vary, and thus, the biases inherent in this model have not been evaluated in a patient cohort. We, therefore, addressed the potential biases in the single point qMT model by acquiring qMT measurements in the cervical SC in patient and control cohorts and evaluated the differences between the control and patient-derived qMT constraints (kmf, T2fR1f, and T2m) for the single point model. We determined that the macromolecular to free pool size ratio (PSR) differences between the control and patient-derived constraints are not significant (p > 0.149 in all cases). Additionally, the derived PSR for each cohort was compared, and we reported that the white matter PSR in healthy volunteers is significantly different from lesions (p < 0.005) and normal appearing white matter (p < 0.02) in all cases. The single point qMT method is thus a valuable method to quantitatively estimate white matter pathology in MS in a clinically feasible scan time.
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Affiliation(s)
- Alex K. Smith
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
- Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Samantha By
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
| | - Bailey D. Lyttle
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
| | - Richard D. Dortch
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Bailey A. Box
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
| | - Lydia J. Mckeithan
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
| | - Saakshi Thukral
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
- Merrol Hyde Magnet School, Hendersonville, TN, USA
| | - Francesca Bagnato
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Neurology, Vanderbilt University, Nashville, TN, USA
| | - Siddharama Pawate
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
- Merrol Hyde Magnet School, Hendersonville, TN, USA
| | - Seth A. Smith
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
- Vanderbilt University Institute of Imaging Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA
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22
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Ma YJ, Chang EY, Carl M, Du J. Quantitative magnetization transfer ultrashort echo time imaging using a time-efficient 3D multispoke Cones sequence. Magn Reson Med 2017; 79:692-700. [PMID: 28470838 DOI: 10.1002/mrm.26716] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 02/19/2017] [Accepted: 03/23/2017] [Indexed: 12/21/2022]
Abstract
PURPOSE To accelerate the quantitative ultrashort echo time imaging using a time-efficient 3D multispoke Cones sequence with magnetization transfer (3D UTE-Cones-MT) and signal modeling. THEORY AND METHODS A 3D UTE-Cones-MT acquisition scheme with multispoke per MT preparation and a modified rectangular pulse (RP) approximation was developed for two-pool MT modeling of macromolecular and water components including their relative fractions, relaxation times and exchange rates. Numerical simulation and cadaveric specimens, including human Achilles tendon and bovine cortical bone, were investigated using a clinical 3T scanner. RESULTS Numerical simulation showed that the modified RP model provided accurate estimation of MT parameters when multispokes were acquired per MT preparation. For the experiment with the Achilles tendon and cortical bone samples, the macromolecular fractions were 20.4 ± 2.0% and 59.4 ± 5.3%, respectively. CONCLUSION The 3D multispoke UTE-Cones-MT sequence can be used for fast volumetric assessment of macromolecular and water components in short T2 tissues. Magn Reson Med 79:692-700, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Ya-Jun Ma
- Department of Radiology, University of California, San Diego, California, USA
| | - Eric Y Chang
- Department of Radiology, University of California, San Diego, California, USA.,Radiology Service, VA San Diego Healthcare System, San Diego, California, USA
| | | | - Jiang Du
- Department of Radiology, University of California, San Diego, California, USA
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23
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Gracien RM, Jurcoane A, Wagner M, Reitz SC, Mayer C, Volz S, Hof SM, Fleischer V, Droby A, Steinmetz H, Zipp F, Hattingen E, Deichmann R, Klein JC. The Relationship between Gray Matter Quantitative MRI and Disability in Secondary Progressive Multiple Sclerosis. PLoS One 2016; 11:e0161036. [PMID: 27513853 PMCID: PMC4981438 DOI: 10.1371/journal.pone.0161036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 07/28/2016] [Indexed: 11/18/2022] Open
Abstract
PURPOSE In secondary progressive Multiple Sclerosis (SPMS), global neurodegeneration as a driver of disability gains importance in comparison to focal inflammatory processes. However, clinical MRI does not visualize changes of tissue composition outside MS lesions. This quantitative MRI (qMRI) study investigated cortical and deep gray matter (GM) proton density (PD) values and T1 relaxation times to explore their potential to assess neuronal damage and its relationship to clinical disability in SPMS. MATERIALS AND METHODS 11 SPMS patients underwent quantitative T1 and PD mapping. Parameter values across the cerebral cortex and deep GM structures were compared with 11 healthy controls, and correlation with disability was investigated for regions exhibiting significant group differences. RESULTS PD was increased in the whole GM, cerebral cortex, thalamus, putamen and pallidum. PD correlated with disability in the whole GM, cerebral cortex, putamen and pallidum. T1 relaxation time was prolonged and correlated with disability in the whole GM and cerebral cortex. CONCLUSION Our study suggests that the qMRI parameters GM PD (which likely indicates replacement of neural tissue with water) and cortical T1 (which reflects cortical damage including and beyond increased water content) are promising qMRI candidates for the assessment of disease status, and are related to disability in SPMS.
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Affiliation(s)
- René-Maxime Gracien
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
- * E-mail:
| | - Alina Jurcoane
- Department of Neuroradiology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Marlies Wagner
- Department of Neuroradiology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Sarah C. Reitz
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Christoph Mayer
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
| | - Steffen Volz
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Stephanie-Michelle Hof
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Vinzenz Fleischer
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | - Amgad Droby
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | | | - Frauke Zipp
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | - Elke Hattingen
- Department of Neuroradiology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Ralf Deichmann
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Johannes C. Klein
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
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24
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Gracien RM, Jurcoane A, Wagner M, Reitz SC, Mayer C, Volz S, Hof SM, Fleischer V, Droby A, Steinmetz H, Groppa S, Hattingen E, Deichmann R, Klein JC. Multimodal quantitative MRI assessment of cortical damage in relapsing-remitting multiple sclerosis. J Magn Reson Imaging 2016; 44:1600-1607. [DOI: 10.1002/jmri.25297] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 04/19/2016] [Indexed: 11/05/2022] Open
Affiliation(s)
- René-Maxime Gracien
- Department of Neurology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Alina Jurcoane
- Department of Neuroradiology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Marlies Wagner
- Department of Neuroradiology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Sarah C. Reitz
- Department of Neurology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Christoph Mayer
- Department of Neurology; Goethe University; Frankfurt/Main Germany
| | - Steffen Volz
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Stephanie-Michelle Hof
- Department of Neurology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Vinzenz Fleischer
- Department of Neurology; Johannes Gutenberg University; Mainz Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN); Johannes Gutenberg-University; Mainz Germany
| | - Amgad Droby
- Department of Neurology; Johannes Gutenberg University; Mainz Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN); Johannes Gutenberg-University; Mainz Germany
| | | | - Sergiu Groppa
- Department of Neurology; Johannes Gutenberg University; Mainz Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN); Johannes Gutenberg-University; Mainz Germany
| | - Elke Hattingen
- Department of Neuroradiology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Ralf Deichmann
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
| | - Johannes C. Klein
- Department of Neurology; Goethe University; Frankfurt/Main Germany
- Brain Imaging Center; Goethe University; Frankfurt/Main Germany
- Nuffield Department of Clinical Neurosciences; University of Oxford; UK
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25
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Smith AK, Dortch RD, Dethrage LM, Lyttle BD, Kang H, Welch EB, Smith SA. Incorporating dixon multi-echo fat water separation for novel quantitative magnetization transfer of the human optic nerve in vivo. Magn Reson Med 2016; 77:707-716. [PMID: 27037720 DOI: 10.1002/mrm.26164] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/08/2016] [Accepted: 01/23/2016] [Indexed: 12/21/2022]
Abstract
PURPOSE The optic nerve (ON) represents the sole pathway between the eyes and brain; consequently, diseases of the ON can have dramatic effects on vision. However, quantitative magnetization transfer (qMT) applications in the ON have been limited to ex vivo studies, in part because of the fatty connective tissue that surrounds the ON, confounding the magnetization transfer (MT) experiment. Therefore, the aim of this study was to implement a multi-echo Dixon fat-water separation approach to remove the fat component from MT images. METHODS MT measurements were taken in a single slice of the ON and frontal lobe using a three-echo Dixon readout, and the water and out-of-phase images were applied to a two-pool model in ON tissue and brain white matter to evaluate the effectiveness of using Dixon fat-water separation to remove fatty tissue from MT images. RESULTS White matter data showed no significant differences between image types; however, there was a significant increase (p < 0.05) in variation in the out-of-phase images in the ON relative to the water images. CONCLUSIONS The results of this study demonstrate that Dixon fat-water separation can be robustly used for accurate MT quantification of anatomies susceptible to partial volume effects resulting from fat. Magn Reson Med 77:707-716, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Alex K Smith
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Richard D Dortch
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Lindsey M Dethrage
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Bailey D Lyttle
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA
| | - Hakmook Kang
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Biostatistics, Vanderbilt University, Nashville, Tennessee, USA.,Center for Quantitative Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - E Brian Welch
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Seth A Smith
- Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.,Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.,Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.,Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee, USA
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26
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Gracien RM, Reitz SC, Hof SM, Fleischer V, Zimmermann H, Droby A, Steinmetz H, Zipp F, Deichmann R, Klein JC. Assessment of cortical damage in early multiple sclerosis with quantitative T2 relaxometry. NMR IN BIOMEDICINE 2016; 29:444-450. [PMID: 26820580 DOI: 10.1002/nbm.3486] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 11/24/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
T2 relaxation time is a quantitative MRI in vivo surrogate of cerebral tissue damage in multiple sclerosis (MS) patients. Cortical T2 prolongation is a known feature in later disease stages, but has not been demonstrated in the cortical normal appearing gray matter (NAGM) in early MS. This study centers on the quantitative evaluation of the tissue parameter T2 in cortical NAGM in a collective of early MS and clinically isolated syndrome (CIS) patients, hypothesizing that T2 prolongation is already present at early disease stages and variable over space, in line with global and focal inflammatory processes in MS. Additionally, magnetization transfer ratio (MTR) mapping was performed for further characterization of the expected cortical T2 alteration. Quantitative T2 and MTR maps were acquired from 12 patients with CIS and early MS, and 12 matched healthy controls. The lesion-free part of the cortical volume was identified, and the mean T2 and MTR values and their standard deviations within the cortical volume were determined. For evaluation of spatial specificity, cortical lobar subregions were tested separately for differences of mean T2 and T2 standard deviation. We detected significantly prolonged T2 in cortical NAGM in patients. T2 prolongation was found across the whole cerebral cortex and in all individual lobar subregions. Significantly higher standard deviations across the respective region of interest were found for the whole cerebral cortex and all subregions, suggesting the occurrence of spatially inhomogeneous cortical damage in all regions studied. A trend was observed for MTR reduction and increased MTR variability across the whole cortex in the MS group, suggesting demyelination. In conclusion, our results suggest that cortical damage in early MS is evidenced by spatially inhomogeneous T2 prolongation which goes beyond demyelination. Iron deposition, which is known to decrease T2, seems less prominent.
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Affiliation(s)
- René-Maxime Gracien
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Sarah C Reitz
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Stephanie-Michelle Hof
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Vinzenz Fleischer
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | - Hilga Zimmermann
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | - Amgad Droby
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | | | - Frauke Zipp
- Department of Neurology, Johannes Gutenberg University, Mainz, Germany
- Neuroimaging Center (NIC) of the Focus Program Translational Neuroscience (FTN), Johannes Gutenberg-University, Mainz, Germany
| | - Ralf Deichmann
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
| | - Johannes C Klein
- Department of Neurology, Goethe University, Frankfurt/Main, Germany
- Brain Imaging Center, Goethe University, Frankfurt/Main, Germany
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27
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Rimkus CDM, Steenwijk MD, Barkhof F. Causes, effects and connectivity changes in MS-related cognitive decline. Dement Neuropsychol 2016; 10:2-11. [PMID: 29213424 PMCID: PMC5674907 DOI: 10.1590/s1980-57642016dn10100002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cognitive decline is a frequent but undervalued aspect of multiple sclerosis (MS). Currently, it remains unclear what the strongest determinants of cognitive dysfunction are, with grey matter damage most directly related to cognitive impairment. Multi-parametric studies seem to indicate that individual factors of MS-pathology are highly interdependent causes of grey matter atrophy and permanent brain damage. They are associated with intermediate functional effects (e.g. in functional MRI) representing a balance between disconnection and (mal) adaptive connectivity changes. Therefore, a more comprehensive MRI approach is warranted, aiming to link structural changes with functional brain organization. To better understand the disconnection syndromes and cognitive decline in MS, this paper reviews the associations between MRI metrics and cognitive performance, by discussing the interactions between multiple facets of MS pathology as determinants of brain damage and how they affect network efficiency.
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Affiliation(s)
- Carolina de Medeiros Rimkus
- Department of Radiology, Laboratory of Medical Investigation (LIM-44), Faculty of Medicine of the University of São Paulo, São Paulo SP, Brazil and Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.,Department of Radiology, Laboratory of Medical Investigation (LIM-44), Faculty of Medicine of the University of São Paulo, São Paulo SP, Brazil and Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Martijn D Steenwijk
- Department of Radiology, Laboratory of Medical Investigation (LIM-44), Faculty of Medicine of the University of São Paulo, São Paulo SP, Brazil and Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.,Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands and Department of Physics and Medical technology, Neuroscience campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Frederik Barkhof
- Department of Radiology, Laboratory of Medical Investigation (LIM-44), Faculty of Medicine of the University of São Paulo, São Paulo SP, Brazil and Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
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28
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Yarnykh VL, Tartaglione EV, Ioannou GN. Fast macromolecular proton fraction mapping of the human liver in vivo for quantitative assessment of hepatic fibrosis. NMR IN BIOMEDICINE 2015; 28:1716-1725. [PMID: 26503401 PMCID: PMC4715674 DOI: 10.1002/nbm.3437] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 06/05/2023]
Abstract
The macromolecular proton fraction (MPF) is a quantitative MRI parameter determining the magnetization transfer (MT) effect in tissues, and is defined as the relative amount of immobile macromolecular protons involved in magnetization exchange with mobile water protons. MPF has the potential to provide a quantitative assessment of fibrous tissue because of the intrinsically high MPF specific for collagen. The goal of this study was to investigate the relationship between histologically determined fibrosis stage and MPF in the liver parenchyma measured using a recently developed fast single-point clinically targeted MPF mapping method. Optimal saturation parameters for single-point liver MPF measurements were determined from the analysis of liver Z spectra in vivo based on the error propagation model. Sixteen patients with chronic hepatitis C viral infection underwent 3-T MRI using an optimized liver MPF mapping protocol. Fourteen patients had prior liver biopsy with histologically staged fibrosis (METAVIR scores F0-F3) and two patients had clinically diagnosed cirrhosis (score F4 was assigned). The protocol included four breath-hold three-dimensional scans with 2 × 3 × 6-mm(3) resolution and 10 transverse sections: dynamic acquisition of MT-weighted and reference images; dynamic acquisition of three images for variable flip angle T1 mapping; dual-echo B0 map; and actual flip angle imaging B1 map. The average liver MPF was determined as the mode of the MPF histograms. MPF was significantly increased in patients with clinically significant fibrosis (scores F2-F4, n = 6) relative to patients with no or mild fibrosis (scores F0-F1, n = 10): 6.49 ± 0.36% versus 5.94 ± 0.26%, p < 0.01 (Mann-Whitney test). MPF and fibrosis scores were strongly positively correlated, with a Spearman's rank correlation coefficient of 0.80 (p < 0.001). This study demonstrates the feasibility of fast MPF mapping of the human liver in vivo and confirms the hypothesis that MPF is increased in hepatic fibrosis and associated with fibrosis stage. MPF may be useful as a non-invasive imaging biomarker of hepatic fibrosis.
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Affiliation(s)
- Vasily L. Yarnykh
- Department of Radiology, University of Washington, Seattle, WA, USA
- Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russian Federation
| | - Erica V. Tartaglione
- Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
| | - George N. Ioannou
- Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, WA, USA
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29
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Mangeat G, Govindarajan ST, Mainero C, Cohen-Adad J. Multivariate combination of magnetization transfer, T2* and B0 orientation to study the myelo-architecture of the in vivo human cortex. Neuroimage 2015; 119:89-102. [PMID: 26095090 DOI: 10.1016/j.neuroimage.2015.06.033] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 05/04/2015] [Accepted: 06/11/2015] [Indexed: 12/21/2022] Open
Abstract
Recently, T2* imaging at 7Tesla (T) MRI was shown to reveal microstructural features of the cortical myeloarchitecture thanks to an increase in contrast-to-noise ratio. However, several confounds hamper the specificity of T2* measures (iron content, blood vessels, tissues orientation). Another metric, magnetization transfer ratio (MTR), is known to also be sensitive to myelin content and thus would be an excellent complementary measure because its underlying contrast mechanisms are different than that from T2*. The goal of this study was thus to combine MTR and T2* using multivariate statistics in order to gain insights into cortical myelin content. Seven healthy subjects were scanned at 7T and 3T to obtain T2* and MTR data, respectively. A multivariate myelin estimation model (MMEM) was developed, and consists in (i) normalizing T2* and MTR values and (ii) extracting their shared information using independent component analysis (ICA). B0 orientation dependence and cortical thickness were also computed and included in the model. Results showed high correlation between MTR and T2* in the whole cortex (r=0.76, p<10(-16)), suggesting that both metrics are partly driven by a common source of contrast, here assumed to be the myelin. Average MTR and T2* were respectively 31.0+/-0.3% and 32.1+/-1.4 ms. Results of the MMEM spatial distribution showed similar trends to that from histological work stained for myelin (r=0.77, p<0.01). Significant right-left differences were detected in the primary motor cortex (p<0.05), the posterior cingulate cortex (p<0.05) and the visual cortex (p<0.05). This study demonstrates that MTR and T2* are highly correlated in the cortex. The combination of MTR, T2*, CT and B0 orientation may be a useful means to study cortical myeloarchitecture with more specificity than using any of the individual methods. The MMEM framework is extendable to other contrasts such as T1 and diffusion MRI.
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Affiliation(s)
- G Mangeat
- Neuroimaging Research Laboratory (NeuroPoly), Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Athinoula A. Martinos Center for Biomedical Imaging, MGH, Charlestown, MA, USA
| | - S T Govindarajan
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, Charlestown, MA, USA
| | - C Mainero
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, Charlestown, MA, USA; Harvard Medical School, Boston, MA, USA
| | - J Cohen-Adad
- Neuroimaging Research Laboratory (NeuroPoly), Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montreal, QC, Canada.
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30
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Dortch RD, Dethrage LM, Gore JC, Smith SA, Li J. Proximal nerve magnetization transfer MRI relates to disability in Charcot-Marie-Tooth diseases. Neurology 2014; 83:1545-53. [PMID: 25253751 DOI: 10.1212/wnl.0000000000000919] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE The objectives of this study were (1) to develop a novel magnetization transfer ratio (MTR) MRI assay of the proximal sciatic nerve (SN), which is inaccessible via current tools for assessing peripheral nerves, and (2) to evaluate the resulting MTR values as a potential biomarker of myelin content changes in patients with Charcot-Marie-Tooth (CMT) diseases. METHODS MTR was measured in the SN of patients with CMT type 1A (CMT1A, n = 10), CMT type 2A (CMT2A, n = 3), hereditary neuropathy with liability to pressure palsies (n = 3), and healthy controls (n = 21). Additional patients without a genetically confirmed subtype (n = 4), but whose family histories and electrophysiologic tests were consistent with CMT, were also included. The relationship between MTR and clinical neuropathy scores was assessed, and the interscan and inter-rater reliability of MTR was estimated. RESULTS Mean volumetric MTR values were significantly decreased in the SN of patients with CMT1A (33.8 ± 3.3 percent units) and CMT2A (31.5 ± 1.9 percent units) relative to controls (37.2 ± 2.3 percent units). A significant relationship between MTR and disability scores was also detected (p = 0.01 for genetically confirmed patients only, p = 0.04 for all patients). From interscan and inter-rater reliability analyses, proximal nerve MTR values were repeatable at the slicewise and mean volumetric levels. CONCLUSIONS MTR measurements may be a viable biomarker of proximal nerve pathology in patients with CMT.
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Affiliation(s)
- Richard D Dortch
- From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN.
| | - Lindsey M Dethrage
- From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN
| | - John C Gore
- From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN
| | - Seth A Smith
- From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN
| | - Jun Li
- From the Department of Radiology and Radiological Sciences (R.D.D., J.C.G., S.A.S.), Vanderbilt University Institute of Imaging Science (R.D.D., L.M.D., J.C.G., S.A.S.), and the Departments of Biomedical Engineering (R.D.D., J.C.G., S.A.S.), Physics and Astronomy (J.C.G., S.A.S.), Molecular Physiology and Biophysics (J.C.G.), and Neurology (J.L.), Vanderbilt University, Nashville, TN
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Smith AK, Dortch RD, Dethrage LM, Smith SA. Rapid, high-resolution quantitative magnetization transfer MRI of the human spinal cord. Neuroimage 2014; 95:106-16. [PMID: 24632465 DOI: 10.1016/j.neuroimage.2014.03.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/05/2014] [Accepted: 03/07/2014] [Indexed: 11/27/2022] Open
Abstract
Quantitative magnetization transfer (qMT) imaging can provide indices describing the interactions between free water protons and immobile macromolecular protons. These indices include the macromolecular proton fraction (MPF), which has been shown to correlate with myelin content in white matter. Because of the long scan times required for high-resolution spinal cord imaging, qMT studies of the human spinal cord have not found wide-spread application. Herein, we investigated whether these limitations could be overcome by utilizing only a single MT-weighted acquisition and a reference measurement, as was recently proposed in the brain. High-resolution, in vivo qMT data were obtained at 3.0T in the spinal cords of healthy volunteers and patients with relapsing remitting multiple sclerosis (MS). Low- and high-resolution acquisitions (low/high resolution=1×1×5mm(3)/0.65×0.65×5mm(3)) with clinically acceptable scan times (12min/7min) were evaluated. We also evaluated the reliability over time and the sensitivity of the model to the assumptions made in the single-point method, both in disease and healthy tissues. Our findings suggest that the single point qMT technique can provide maps of the MPF in the spinal cord in vivo with excellent grey/white matter contrast, can be reliably obtained within reasonable scan times, and are sensitive to MS pathology. Consistent with previous qMT studies in the brain, the observed MPF values were higher in healthy white matter (0.16±0.01) than in grey matter (0.13±0.01) and in MS lesions (0.09±0.01). The single point qMT technique applied at high resolution provides an improved method for obtaining qMT in the human spinal cord and may offer a reliable outcome measure for evaluating spinal cord disease.
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Affiliation(s)
- Alex K Smith
- Department of Biomedical Engineering, Vanderbilt University, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA
| | - Richard D Dortch
- Department of Biomedical Engineering, Vanderbilt University, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, USA
| | - Lindsey M Dethrage
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA
| | - Seth A Smith
- Department of Biomedical Engineering, Vanderbilt University, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA; Department of Radiology and Radiological Sciences, Vanderbilt University, USA; Department of Physics and Astronomy, Vanderbilt University, USA.
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Varma G, Duhamel G, de Bazelaire C, Alsop DC. Magnetization transfer from inhomogeneously broadened lines: A potential marker for myelin. Magn Reson Med 2014; 73:614-22. [PMID: 24604578 DOI: 10.1002/mrm.25174] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 12/30/2013] [Accepted: 01/17/2014] [Indexed: 02/03/2023]
Abstract
PURPOSE To characterize a new approach to magnetization transfer (MT) imaging with improved specificity for myelinated tissues relative to conventional MT. METHODS Magnetization transfer preparation sequences were implemented with all radiofrequency power centered on a single frequency and also with power evenly divided between positive and negative frequencies. Dual frequency saturation was achieved both with short, alternating frequency pulses and with sinusoidal modulation of continuous irradiation. Images following preparation were acquired with a single shot fast spin echo sequence. Single and dual frequency preparation should achieve similar saturation of molecules except for those with inhomogenously broadened lines. Inhomogenous MT (IHMT) images were generated by subtraction of dual from single frequency prepared images. IHMT imaging was performed with different power and frequency in the brains of normal volunteers. RESULTS The IHMT method demonstrated a greater white/gray matter ratio than conventional MT and virtual elimination of signal in scalp and other unmyelinated tissues. IHMT exceeded 5% of the fully relaxed magnetization in white matter. A broad frequency spectrum and signs of axonal angular dependence at high frequency were observed that are consistent with dipolar broadening. CONCLUSION IHMT shows promise for myelin-specific imaging. Further study of physical mechanisms and diagnostic sensitivity are merited.
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Affiliation(s)
- Gopal Varma
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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Li W, Zhang Z, Nicolai J, Yang GY, Omary RA, Larson AC. Quantitative magnetization transfer MRI of desmoplasia in pancreatic ductal adenocarcinoma xenografts. NMR IN BIOMEDICINE 2013; 26:1688-95. [PMID: 23940016 PMCID: PMC3838498 DOI: 10.1002/nbm.3004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 06/26/2013] [Accepted: 06/27/2013] [Indexed: 05/15/2023]
Abstract
Quantitative assessment of desmoplasia in pancreatic ductal adenocarcinoma (PDAC) may be critical for staging or prediction of response to therapy. We performed quantitative magnetization transfer (qMT) MRI measurements in 18 mouse xenograft tumors generated from three PDAC cell lines. The qMT parameter bound proton fraction (BPF) was found to be significantly higher in tumors grown using the BxPC-3 cell line (5.31 ± 0.87, mean ± standard deviation) compared with the BPF measured for tumors grown from Panc-1 (3.65 ± 0.60) and Capan-1 (1.50 ± 0.58) cell lines (P < 0.05 for each comparison). Histologic measurements demonstrated a similar trend; BxPC-3 tumors had significantly higher fibrosis levels (percentage of fibrotic tissue area, 6.21 ± 2.10) compared with Panc-1 (2.88 ± 1.13) and Capan-1 (1.69 ± 1.01) tumors. BPF was well correlated with quantitative fibrosis levels (r = 0.77, P < 0.01). Our results indicate that qMT measurements offer the potential to noninvasively quantify fibrosis levels in PDAC mouse xenograft models and thus serve as a valuable in vivo biomarker of desmoplasia in PDAC.
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Affiliation(s)
- Weiguo Li
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Zhuoli Zhang
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois, USA
| | - Jodi Nicolai
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Guang-Yu Yang
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois, USA
- Department of Pathology, Northwestern University, Chicago, IL, 60611, USA
| | - Reed A. Omary
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA
| | - Andrew C. Larson
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
- Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, USA
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Samson RS, Ciccarelli O, Kachramanoglou C, Brightman L, Lutti A, Thomas DL, Weiskopf N, Wheeler-Kingshott CAM. Tissue- and column-specific measurements from multi-parameter mapping of the human cervical spinal cord at 3 T. NMR IN BIOMEDICINE 2013; 26:1823-30. [PMID: 24105923 PMCID: PMC4034603 DOI: 10.1002/nbm.3022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 06/25/2013] [Accepted: 08/09/2013] [Indexed: 05/05/2023]
Abstract
The aim of this study was to quantify a range of MR parameters [apparent proton density, longitudinal relaxation time T1, magnetisation transfer (MT) ratio, MT saturation (which represents the additional percentage MT saturation of the longitudinal magnetisation caused by a single MT pulse) and apparent transverse relaxation rate R2*] in the white matter columns and grey matter of the healthy cervical spinal cord. The cervical cords of 13 healthy volunteers were scanned at 3 T using a protocol optimised for multi-parameter mapping. Intra-subject co-registration was performed using linear registration, and tissue- and column-specific parameter values were calculated. Cervical cord parameter values measured from levels C1-C5 in 13 subjects are: apparent proton density, 4822 ± 718 a.u.; MT ratio, 40.4 ± 1.53 p.u.; MT saturation, 1.40 ± 0.12 p.u.; T1 = 1848 ± 143 ms; R2* = 22.6 ± 1.53 s(-1). Inter-subject coefficients of variation were low in both the cervical cord and tissue- and column-specific measurements, illustrating the potential of this method for the investigation of changes in these parameters caused by pathology. In summary, an optimised cervical cord multi-parameter mapping protocol was developed, enabling tissue- and column-specific measurements to be made. This technique has the potential to provide insight into the pathological processes occurring in the cervical cord affected by neurological disorders.
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Affiliation(s)
- RS Samson
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of NeurologyQueen Square, London, UK
- *Correspondence to: R. Samson, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK., E-mail:
| | - O Ciccarelli
- NMR Research Unit, Queen Square MS Centre, Department of Brain Repair and Rehabilitation, UCL Institute of NeurologyQueen Square, London, UK
| | - C Kachramanoglou
- NMR Research Unit, Queen Square MS Centre, Department of Brain Repair and Rehabilitation, UCL Institute of NeurologyQueen Square, London, UK
| | | | - A Lutti
- Wellcome Trust Centre for Neuroimaging, UCL Institute of NeurologyQueen Square, London, UK
| | - DL Thomas
- Neuroradiological Academic Unit, Department of Brain Repair and Rehabilitation, UCL Institute of NeurologyQueen Square, London, UK
| | - N Weiskopf
- Wellcome Trust Centre for Neuroimaging, UCL Institute of NeurologyQueen Square, London, UK
| | - CAM Wheeler-Kingshott
- NMR Research Unit, Queen Square MS Centre, Department of Neuroinflammation, UCL Institute of NeurologyQueen Square, London, UK
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Bigot C, Vanhoutte G, Verhoye M, Van der Linden A. Magnetization transfer contrast imaging reveals amyloid pathology in Alzheimer's disease transgenic mice. Neuroimage 2013; 87:111-9. [PMID: 24188815 DOI: 10.1016/j.neuroimage.2013.10.056] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/19/2013] [Accepted: 10/26/2013] [Indexed: 12/18/2022] Open
Abstract
The presence of amyloid plaques in the brain is one of the pathological hallmarks of Alzheimer's disease, which might already be present in the early stage of the disease. Therefore it is important to track amyloid plaques as early as possible. In this paper, we report magnetization transfer contrast magnetic resonance imaging (MTC MRI) as a novel approach to detect amyloid plaques in vivo. Two mice models, APP/PS1 and BRI, developing amyloid pathology were investigated with MTC MRI, T2 relaxation measurements and immunohistochemistry (IHC). MT-ratios of several brain regions were compared to T2-values and correlated with quantitative IHC, revealing amyloid load and gliosis in different brain regions. APP/PS1 mice develop large compact plaques, resembling late stage Alzheimer's disease, while rather small and diffuse plaques are deposited in BRI mice, reflecting early stage of Alzheimer's disease. We found significantly higher MT-ratio's in the brain of APP/PS1 mice as compared to their controls and similar trends in BRI mice. A region based MT-ratio and IHC analysis and correlations between MT-ratios and quantitative IHC indicate amyloid plaques as the main substrate for altered MT-ratios in transgenic animals. We additionally demonstrated the improved sensitivity of MTC MRI to amyloid pathology as compared to traditional T2 relaxation measurements. Our results suggest that MTC MRI reveals extensive, and potentially even early amyloid pathology. Further unraveling the MT-effect of each pathological feature during each stage of AD might indicate MTC MRI as a useful diagnostic technique.
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Affiliation(s)
- Christian Bigot
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1 Uc, 2610 Wilrijk, Antwerp, Belgium.
| | - Greetje Vanhoutte
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1 Uc, 2610 Wilrijk, Antwerp, Belgium.
| | - Marleen Verhoye
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1 Uc, 2610 Wilrijk, Antwerp, Belgium.
| | - Annemie Van der Linden
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1 Uc, 2610 Wilrijk, Antwerp, Belgium.
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Sidharthan S, Hutten R, Glielmi C, Du H, Malone F, Ragin AB, Edelman RR, Wu Y. Hippocampal Magnetization Transfer Ratio at 3T: Validation of Automated Postprocessing and Comparison of Quantification Metrics. J Neuroimaging 2013; 23:484-90. [DOI: 10.1111/j.1552-6569.2011.00697.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Janve VA, Zu Z, Yao SY, Li K, Zhang FL, Wilson KJ, Ou X, Does MD, Subramaniam S, Gochberg DF. The radial diffusivity and magnetization transfer pool size ratio are sensitive markers for demyelination in a rat model of type III multiple sclerosis (MS) lesions. Neuroimage 2013; 74:298-305. [PMID: 23481461 DOI: 10.1016/j.neuroimage.2013.02.034] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 01/31/2013] [Accepted: 02/19/2013] [Indexed: 10/27/2022] Open
Abstract
Determining biophysical sensitivity and specificity of quantitative magnetic resonance imaging is essential to develop effective imaging metrics of neurodegeneration. Among these metrics, apparent pool size ratio (PSR) from quantitative magnetization transfer (qMT) imaging and radial diffusivity (RD) from diffusion tensor imaging (DTI) are both known to relate to histological measure of myelin density and integrity. However their relative sensitivities towards quantitative myelin detection are unknown. In this study, we correlated high-resolution quantitative magnetic resonance imaging measures of subvoxel tissue structures with corresponding quantitative myelin histology in a lipopolysaccharide (LPS) mediated animal model of MS. Specifically, we acquired quantitative magnetization transfer (qMT) and diffusion tensor imaging (DTI) metrics (on the same tissue sample) in an animal model system of type III oligodendrogliopathy which lacked prominent lymphocytic infiltration, a system that had not been previously examined with quantitative MRI. We find that the qMT measured apparent pool size ratio (PSR) showed the strongest correlation with a histological measure of myelin content. DTI measured RD showed the next strongest correlation, and other DTI and relaxation parameters (such as the longitudinal relaxation rate (R1f) or fractional anisotropy (FA)) showed considerably weaker correlations with myelin content.
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Affiliation(s)
- Vaibhav A Janve
- Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232-2310, USA
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38
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Tofts PS, Collins DJ. Multicentre imaging measurements for oncology and in the brain. Br J Radiol 2012; 84 Spec No 2:S213-26. [PMID: 22433831 DOI: 10.1259/bjr/74316620] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Multicentre imaging studies of brain tumours (and other tumour and brain studies) can enable a large group of patients to be studied, yet they present challenging technical problems. Differences between centres can be characterised, understood and minimised by use of phantoms (test objects) and normal control subjects. Normal white matter forms an excellent standard for some MRI parameters (e.g. diffusion or magnetisation transfer) because the normal biological range is low (<2-3%) and the measurements will reflect this, provided the acquisition sequence is controlled. MR phantoms have benefits and they are necessary for some parameters (e.g. tumour volume). Techniques for temperature monitoring and control are given. In a multicentre study or treatment trial, between-centre variation should be minimised. In a cross-sectional study, all groups should be represented at each centre and the effect of centre added as a covariate in the statistical analysis. In a serial study of disease progression or treatment effect, individual patients should receive all of their scans at the same centre; the power is then limited by the within-subject reproducibility. Sources of variation that are generic to any imaging method and analysis parameters include MR sequence mismatch, B(1) errors, CT effective tube potential, region of interest generation and segmentation procedure. Specific tissue parameters are analysed in detail to identify the major sources of variation and the most appropriate phantoms or normal studies. These include dynamic contrast-enhanced and dynamic susceptibility contrast gadolinium imaging, T(1), diffusion, magnetisation transfer, spectroscopy, tumour volume, arterial spin labelling and CT perfusion.
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Affiliation(s)
- P S Tofts
- Brighton and Sussex Medical School, Brighton, UK.
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39
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Nossin-Manor R, Card D, Morris D, Noormohamed S, Shroff MM, Whyte HE, Taylor MJ, Sled JG. Quantitative MRI in the very preterm brain: assessing tissue organization and myelination using magnetization transfer, diffusion tensor and T₁ imaging. Neuroimage 2012; 64:505-16. [PMID: 22982360 DOI: 10.1016/j.neuroimage.2012.08.086] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 08/17/2012] [Accepted: 08/28/2012] [Indexed: 01/08/2023] Open
Abstract
Magnetization transfer ratio (MTR), diffusion tensor imaging (DTI) parameters and T(1) relaxometry values were used to create parametric maps characterizing the tissue microstructure of the neonatal brain in infants born very premature (24-32 gestational weeks) and scanned at preterm and term equivalent age. Group-wise image registration was used to determine anatomical correspondence between individual scans and the pooled parametric data at the preterm and term ages. These parametric maps showed distinct contrasts whose interrelations varied across brain regions and between the preterm and term period. Discrete patterns of regional variation were observed for the different quantitative parameters, providing evidence that MRI is sensitive to multiple independent aspects of brain maturation. MTR values showed a marked change in the pattern of regional variation at term equivalent age compared to the preterm period such that the ordinal ranking of regions by signal contrast changed. This was unlike all other parameters where the regional ranking was preserved at the two time points. Interpreting the data in terms of myelination and structural organization, we report on the concordance with available histological data and demonstrate the value of quantitative MRI for tracking brain maturation over the neonatal period.
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Affiliation(s)
- Revital Nossin-Manor
- Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
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40
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Dortch RD, Moore J, Li K, Jankiewicz M, Gochberg DF, Hirtle JA, Gore JC, Smith SA. Quantitative magnetization transfer imaging of human brain at 7 T. Neuroimage 2012; 64:640-9. [PMID: 22940589 DOI: 10.1016/j.neuroimage.2012.08.047] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 08/10/2012] [Accepted: 08/18/2012] [Indexed: 11/26/2022] Open
Abstract
Quantitative magnetization transfer (qMT) imaging yields indices describing the interactions between free water protons and immobile macromolecular protons. These indices include the macromolecular to free pool size ratio (PSR), which has been shown to be correlated with myelin content in white matter. Because of the long scan times required for whole-brain imaging (≈20-30 min), qMT studies of the human brain have not found widespread application. Herein, we investigated whether the increased signal-to-noise ratio available at 7.0 T could be used to reduce qMT scan times. More specifically, we developed a selective inversion recovery (SIR) qMT imaging protocol with a i) novel transmit radiofrequency (B(1)(+)) and static field (B(0)) insensitive inversion pulse, ii) turbo field-echo readout, and iii) reduced TR. In vivo qMT data were obtained in the brains of healthy volunteers at 7.0 T using the resulting protocol (scan time≈40 s/slice, resolution=2 × 2 × 3 mm(3)). Reliability was also assessed in repeated acquisitions. The results of this study demonstrate that SIR qMT imaging can be reliably performed within the radiofrequency power restrictions present at 7.0 T, even in the presence of large B(1)(+) and B(0) inhomogeneities. Consistent with qMT studies at lower field strengths, the observed PSR values were higher in white matter (mean±SD=17.6 ± 1.3%) relative to gray matter (10.3 ± 1.6%) at 7.0 T. In addition, regional variations in PSR were observed in white matter. Together, these results suggest that qMT measurements are feasible at 7.0 T and may eventually allow for the high-resolution assessment of changes in composition throughout the normal and diseased human brain in vivo.
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Affiliation(s)
- Richard D Dortch
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, USA.
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41
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Yiannakas MC, Kearney H, Samson RS, Chard DT, Ciccarelli O, Miller DH, Wheeler-Kingshott CAM. Feasibility of grey matter and white matter segmentation of the upper cervical cord in vivo: a pilot study with application to magnetisation transfer measurements. Neuroimage 2012; 63:1054-9. [PMID: 22850571 DOI: 10.1016/j.neuroimage.2012.07.048] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Revised: 07/17/2012] [Accepted: 07/19/2012] [Indexed: 10/28/2022] Open
Abstract
Spinal cord pathology can be functionally very important in neurological disease. Pathological studies have demonstrated the involvement of spinal cord grey matter (GM) and white matter (WM) in several diseases, although the clinical relevance of abnormalities detected histopathologically is difficult to assess without a reliable way to assess cord GM and WM in vivo. In this study, the feasibility of GM and WM segmentation was investigated in the upper cervical spinal cord of 10 healthy subjects, using high-resolution images acquired with a commercially available 3D gradient-echo pulse sequence at 3T. For each healthy subject, tissue-specific (i.e. WM and GM) cross-sectional areas were segmented and total volumes calculated from a 15 mm section acquired at the level of C2-3 intervertebral disc and magnetisation transfer ratio (MTR) values within the extracted volumes were also determined, as an example of GM and WM quantitative measurements in the cervical cord. Mean (± SD) total cord cross-sectional area (TCA) and total cord volume (TCV) of the section studied across 10 healthy subjects were 86.9 (± 7.7) mm(2) and 1302.8 (± 115) mm(3), respectively; mean (±SD) total GM cross-sectional area (TGMA) and total GM volume (TGMV) were 14.6 (± 1.1) mm(2) and 218.3 (± 16.8) mm(3), respectively; mean (± SD) GM volume fraction (GMVF) was 0.17 (± 0.01); mean (± SD) MTR of the total WM volume (WM-MTR) was 51.4 (± 1.5) and mean (± SD) MTR of the total GM volume (GM-MTR) was 49.7 (± 1.6). The mean scan-rescan, intra- and inter-observer % coefficient of variation for measuring the TCA were 0.7%, 0.5% and 0.5% and for measuring the TGMA were 6.5%, 5.4% and 12.7%. The difference between WM-MTR and GM-MTR was found to be statistically significant (p=0.00006). This study has shown that GM and WM segmentation in the cervical cord is possible and the MR imaging protocol and analysis method presented here in healthy controls can be potentially extended to study the cervical cord in disease states, with the option to explore further quantitative measurements alongside MTR.
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Affiliation(s)
- M C Yiannakas
- NMR Research Unit, UCL Institute of Neurology, London, UK.
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42
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Nossin-Manor R, Chung AD, Whyte HEA, Shroff MM, Taylor MJ, Sled JG. Deep Gray Matter Maturation in Very Preterm Neonates: Regional Variations and Pathology-related Age-dependent Changes in Magnetization Transfer Ratio. Radiology 2012; 263:510-7. [DOI: 10.1148/radiol.12110367] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Alexander AL, Hurley SA, Samsonov AA, Adluru N, Hosseinbor AP, Mossahebi P, Tromp DPM, Zakszewski E, Field AS. Characterization of cerebral white matter properties using quantitative magnetic resonance imaging stains. Brain Connect 2012; 1:423-46. [PMID: 22432902 DOI: 10.1089/brain.2011.0071] [Citation(s) in RCA: 330] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The image contrast in magnetic resonance imaging (MRI) is highly sensitive to several mechanisms that are modulated by the properties of the tissue environment. The degree and type of contrast weighting may be viewed as image filters that accentuate specific tissue properties. Maps of quantitative measures of these mechanisms, akin to microstructural/environmental-specific tissue stains, may be generated to characterize the MRI and physiological properties of biological tissues. In this article, three quantitative MRI (qMRI) methods for characterizing white matter (WM) microstructural properties are reviewed. All of these measures measure complementary aspects of how water interacts with the tissue environment. Diffusion MRI, including diffusion tensor imaging, characterizes the diffusion of water in the tissues and is sensitive to the microstructural density, spacing, and orientational organization of tissue membranes, including myelin. Magnetization transfer imaging characterizes the amount and degree of magnetization exchange between free water and macromolecules like proteins found in the myelin bilayers. Relaxometry measures the MRI relaxation constants T1 and T2, which in WM have a component associated with the water trapped in the myelin bilayers. The conduction of signals between distant brain regions occurs primarily through myelinated WM tracts; thus, these methods are potential indicators of pathology and structural connectivity in the brain. This article provides an overview of the qMRI stain mechanisms, acquisition and analysis strategies, and applications for these qMRI stains.
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Affiliation(s)
- Andrew L Alexander
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705, USA.
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Wu Y, Du H, Storey P, Glielmi C, Malone F, Sidharthan S, Ragin A, Tofts PS, Edelman RR. Comprehensive brain analysis with automated high-resolution magnetization transfer measurements. J Magn Reson Imaging 2011; 35:309-17. [PMID: 21990125 DOI: 10.1002/jmri.22835] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 09/14/2011] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To enhance the reliability and spatial resolution of magnetization transfer ratio (MTR) measurements for interrogation of subcortical brain regions with an automated volume of interest (VOI) approach. MATERIALS AND METHODS A 3D magnetization transfer (MT) sequence was acquired using a scan-rescan imaging protocol in nine healthy volunteers. VOI definition masks for the MTR measurements were generated using FreeSurfer and compared to a manual region of interest (ROI) approach. (The longitudinal stability of MTR was monitored using agar gel phantom over a 5-month period.) Intraclass correlation coefficients (ICCs), coefficients of variation (CVs), and instrumental standard deviation (ISD) were determined. RESULTS CVs ranged from 1.29%-2.64% (automated) vs. 1.30%-3.40% (manual). ISDs ranged from 0.62-1.10 pu (automated) vs. 0.68-1.67 pu (manual). The SD of the running difference was 1.70% for the phantom scans. The Bland-Altman method indicated interchangeability of the automated VOI and manual ROI measurements. CONCLUSION The automated VOI approach for MTR measurement yielded higher ICCs, lower CVs, and lower ISDs compared to the manual method, supporting the utility of this strategy. These results demonstrate the feasibility of obtaining reliable MTR measurements in hippocampus and other critical subcortical regions.
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Affiliation(s)
- Ying Wu
- Radiology, NorthShore University HealthSystem, Evanston, Illinois 60201, USA.
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Giulietti G, Bozzali M, Figura V, Spanò B, Perri R, Marra C, Lacidogna G, Giubilei F, Caltagirone C, Cercignani M. Quantitative magnetization transfer provides information complementary to grey matter atrophy in Alzheimer's disease brains. Neuroimage 2011; 59:1114-22. [PMID: 21983184 DOI: 10.1016/j.neuroimage.2011.09.043] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022] Open
Abstract
Preliminary studies, based on a region-of-interest approach, suggest that quantitative magnetization transfer (qMT), an extension of magnetization transfer imaging, provides complementary information to conventional magnetic resonance imaging (MRI) in the characterisation of Alzheimer's disease (AD). The aim of this study was to extend these findings to the whole brain, using a voxel-wise approach. We recruited 19AD patients and 11 healthy subjects (HS). All subjects had an MRI acquisition at 3.0T including a T(1)-weighted volume, 12 MT-weighted volumes for qMT, and data for computing T(1) and B(1) maps. The T(1)-weighted volumes were processed to yield grey matter (GM) volumetric maps, while the other sequences were used to compute qMT parametric maps of the whole brain. qMT maps were warped to standard space and smoothed, and subsequently compared between groups. Of all the qMT parameters considered, only the forward exchange rate, RM(0)(B), showed significant group differences. These images were therefore retained for the multimodal statistical analysis, designed to locate brain regions of RM(0)(B) differences between AD and HS groups, adjusting for local GM atrophy. Widespread areas of reduced RM(0)(B) were found in AD patients, mainly located in the hippocampus, in the temporal lobe, in the posterior cingulate and in the parietal cortex. These results indicate that, among qMT parameters, RM(0)(B) is the most sensitive to AD pathology. This quantity is altered in the hippocampus of patients with AD (as found by previous works) but also in other brain areas, that PET studies have highlighted as involved with both, reduced glucose metabolism and amyloid β deposition. RM(0)(B) might reflect, through the measurement of the efficiency of MT exchange, some information with a specific pathological counterpart. Given previous evidence of a strict relationship between RM(0)(B) and intracellular pH, an intriguing speculation is that our findings might reflect metabolic changes related to mitochondrial dysfunction, which has been proposed as a contributor to neurodegeneration in AD.
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Affiliation(s)
- Giovanni Giulietti
- Neuroimaging Laboratory, Santa Lucia Foundation IRCCS, via Ardeatina 306, 00179 Rome, Italy.
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46
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Dortch RD, Li K, Gochberg DF, Welch EB, Dula AN, Tamhane AA, Gore JC, Smith SA. Quantitative magnetization transfer imaging in human brain at 3 T via selective inversion recovery. Magn Reson Med 2011; 66:1346-52. [PMID: 21608030 DOI: 10.1002/mrm.22928] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 01/07/2011] [Accepted: 02/26/2011] [Indexed: 11/09/2022]
Abstract
Quantitative magnetization transfer imaging yields indices describing the interactions between free water protons and immobile, macromolecular protons-including the macromolecular to free pool size ratio (PSR) and the rate of magnetization transfer between pools k(mf) . This study describes the first implementation of the selective inversion recovery quantitative magnetization transfer method on a clinical 3.0-T scanner in human brain in vivo. Selective inversion recovery data were acquired at 16 different inversion times in nine healthy subjects and two patients with relapsing remitting multiple sclerosis. Data were collected using a fast spin-echo readout and reduced repetition time, resulting in an acquisition time of 4 min for a single slice. In healthy subjects, excellent intersubject and intrasubject reproducibilities (assessed via repeated measures) were demonstrated. Furthermore, PSR values in white (mean ± SD = 11.4 ± 1.2%) and gray matter (7.5 ± 0.7%) were consistent with previously reported values, while k(mf) values were approximately 2-fold slower in both white (11 ± 2 s(-1) ) and gray matter (15 ± 6 s(-1) ). In relapsing remitting multiple sclerosis patients, quantitative magnetization transfer indices were sensitive to pathological changes in lesions and in normal appearing white matter.
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Affiliation(s)
- Richard D Dortch
- Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
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Mangia S, De Martino F, Liimatainen T, Garwood M, Michaeli S. Magnetization transfer using inversion recovery during off-resonance irradiation. Magn Reson Imaging 2011; 29:1346-50. [PMID: 21601405 DOI: 10.1016/j.mri.2011.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 03/31/2011] [Accepted: 04/04/2011] [Indexed: 10/18/2022]
Abstract
Estimation of magnetization transfer (MT) parameters in vivo can be compromised by an inability to drive the magnetization to a steady state using allowable levels of radiofrequency (RF) irradiation, due to safety concerns (tissue heating and specific absorption rate (SAR)). Rather than increasing the RF duration or amplitude, here we propose to circumvent the SAR limitation by sampling the formation of the steady state in separate measurements made with the magnetization initially along the -z and +z axis of the laboratory frame, i.e. with or without an on-resonance inversion pulse prior to the off-resonance irradiation. Results from human brain imaging demonstrate that this choice provides a tremendous benefit in the fitting procedure used to estimate MT parameters. The resulting parametric maps are characterized by notably increased tissue specificity as compared to those obtained with the standard MT acquisition in which magnetization is initially along the +z axis only.
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Affiliation(s)
- Silvia Mangia
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota School of Medicine, Minneapolis, MN 55455, USA.
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48
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Gloor M, Scheffler K, Bieri O. Intrascanner and interscanner variability of magnetization transfer-sensitized balanced steady-state free precession imaging. Magn Reson Med 2010; 65:1112-7. [DOI: 10.1002/mrm.22694] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 07/26/2010] [Accepted: 09/24/2010] [Indexed: 11/11/2022]
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Sinclair CDJ, Samson RS, Thomas DL, Weiskopf N, Lutti A, Thornton JS, Golay X. Quantitative magnetization transfer in in vivo healthy human skeletal muscle at 3 T. Magn Reson Med 2010; 64:1739-48. [PMID: 20665899 PMCID: PMC3077519 DOI: 10.1002/mrm.22562] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 06/02/2010] [Accepted: 06/15/2010] [Indexed: 01/12/2023]
Abstract
The value of quantitative MR methods as potential biomarkers in neuromuscular disease is being increasingly recognized. Previous studies of the magnetization transfer ratio have demonstrated sensitivity to muscle disease. The aim of this work was to investigate quantitative magnetization transfer imaging of skeletal muscle in healthy subjects at 3 T to evaluate its potential use in pathological muscle. The lower limb of 10 subjects was imaged using a 3D fast low-angle shot acquisition with variable magnetization transfer saturation pulse frequencies and amplitudes. The data were analyzed with an established quantitative two-pool model of magnetization transfer. T1 and B1 amplitude of excitation radiofrequency field maps were acquired and used as inputs to the quantitative magnetization transfer model, allowing properties of the free and restricted proton pools in muscle to be evaluated in seven different muscles in a region of interest analysis. The average restricted pool T2 relaxation time was found to be 5.9 ± 0.2μs in the soleus muscle and the restricted proton pool fraction was 8 ± 1%. Quantitative magnetization transfer imaging of muscle offers potential new biomarkers in muscle disease within a clinically feasible scan time. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc.
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Affiliation(s)
- Christopher D J Sinclair
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London, United Kingdom.
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50
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MTR variations in normal adult brain structures using balanced steady-state free precession. Neuroradiology 2010; 53:159-67. [DOI: 10.1007/s00234-010-0714-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 04/30/2010] [Indexed: 11/25/2022]
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