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PURPOSE OF REVIEW: To review recent clinical uses of low-field magnetic resonance imaging (MRI) to guide incorporation into neurological practice. RECENT FINDINGS: Use of low-field MRI has been demonstrated in applications including tumours, vascular pathologies, multiple sclerosis, brain injury, and paediatrics. Safety, workflow, and image quality have also been evaluated. SUMMARY: Low-field MRI has the potential to increase access to critical brain imaging for patients who otherwise may not obtain imaging in a timely manner. This includes areas such as the intensive care unit and emergency room, where patients could be imaged at the point of care rather than be transported to the MRI scanner. Such systems are often more affordable than conventional systems, allowing them to be more easily deployed in resource constrained settings. A variety of systems are available on the market or in a research setting and are currently being used to determine clinical uses for these devices. The utility of such devices must be fully evaluated in clinical scenarios before adoption into standard practice can be achieved. This review summarizes recent clinical uses of low-field MR as well as safety, workflows, and image quality to aid practitioners in assessing this new technology.
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Imageamento por Ressonância Magnética , Doenças do Sistema Nervoso , Humanos , Imageamento por Ressonância Magnética/métodos , Doenças do Sistema Nervoso/diagnóstico por imagem , Doenças do Sistema Nervoso/diagnóstico , Encéfalo/diagnóstico por imagemRESUMO
Although 7 T MRI research has contributed much to our understanding of multiple sclerosis (MS) pathology, most prior data has come from small, single-center studies with varying methods. In order to truly know if such findings have widespread applicability, multicenter methods and studies are needed. To address this, members of the North American Imaging in MS (NAIMS) Cooperative worked together to create a multicenter collaborative study of 7 T MRI in MS. In this manuscript, we describe the methods we have developed for the purpose of pooling together a large, retrospective dataset of 7 T MRIs acquired in multiple MS studies at five institutions. To date, this group has contributed five-hundred and twenty-eight 7 T MRI scans from 350 individuals with MS to a common data repository, with plans to continue to increase this sample size in the coming years. We have developed unified methods for image processing for data harmonization and lesion identification/segmentation. We report here our initial observations on intersite differences in acquisition, which includes site/device differences in brain coverage and image quality. We also report on the development of our methods and training of image evaluators, which resulted in median Dice Similarity Coefficients for trained raters' annotation of cortical and deep gray matter lesions, paramagnetic rim lesions, and meningeal enhancement between 0.73 and 0.82 compared to final consensus masks. We expect this publication to act as a resource for other investigators aiming to combine multicenter 7 T MRI datasets for the study of MS, in addition to providing a methodological reference for all future analysis projects to stem from the development of this dataset.
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Imageamento por Ressonância Magnética , Esclerose Múltipla , Humanos , Esclerose Múltipla/diagnóstico por imagem , Esclerose Múltipla/patologia , Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/normas , Adulto , Feminino , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Processamento de Imagem Assistida por Computador/métodosRESUMO
BACKGROUND: Multiple Sclerosis (MS) affects people in their most productive years of life. Consequently, MS can substantially affect employment and work-related outcomes. OBJECTIVES: This study characterizes productivity loss and employment status of people with multiple sclerosis (pwMS) and investigates associated factors. METHODS: We used baseline data collected as part of the Canadian Prospective Cohort Study to Understand Progression in Multiple Sclerosis (CanProCo). Using the Valuation of Lost Productivity questionnaire, we measured MS-related paid work productivity loss for those employed, productivity losses incurred by those unemployed (i.e. lost employment time), and unpaid work productivity losses for all. A set of sociodemographic, disease, and performance-related factors were investigated using a two-part regression model for productivity loss and a multinomial logistic model for employment status. RESULTS: From the cohort of 888 pwMS enrolled at baseline (mostly showing mild to moderate disability), 75% were employed, and of those unemployed, 69% attributed their unemployment to health-related issues. Total productivity loss over a 3-month period averaged 64 and 395 hours for those employed and unemployed, respectively. Some factors that affected productivity loss and employment status included use of disease-modifying therapies, fatigue, and performance indicators such as cognitive processing speed. CONCLUSION: Productivity loss experienced by employed and unemployed pwMS is substantial. Targeting the identified modifiable factors is likely to improve work productivity and permanence of MS patients in the workforce.
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Esclerose Múltipla , Humanos , Esclerose Múltipla/psicologia , Estudos Prospectivos , Canadá , Emprego , DesempregoRESUMO
BACKGROUND: Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system characterized by two major and interconnected hallmarks: inflammation and progressive neurodegeneration. OBJECTIVE: The aim of this work was to compare neurodegenerative processes, in the form of global and regional brain volume loss rates, in healthy controls (HCs) and in patients with relapsing MS (RMS) treated with ocrelizumab, which suppresses acute inflammation. METHODS: Whole brain, white matter, cortical gray matter, thalamic, and cerebellar volume loss rates were assessed in 44 HCs that were part of a substudy in the OPERA II randomized controlled trial (NCT01412333) and 59 patients with RMS enrolled in the same substudy as well as age- and sex-matched patients in OPERA I (NCT01247324) and II. Volume loss rates were computed using random coefficients models over a period of 2 years. RESULTS: Ocrelizumab-treated patients showed global and regional brain volume loss rates that were approaching that of HCs. CONCLUSION: These findings are consistent with an important role of inflammation on overall tissue loss and the role of ocrelizumab in reducing this phenomenon.
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Envelhecimento Saudável , Esclerose Múltipla Crônica Progressiva , Esclerose Múltipla Recidivante-Remitente , Esclerose Múltipla , Humanos , Esclerose Múltipla/induzido quimicamente , Fatores Imunológicos/efeitos adversos , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Imageamento por Ressonância Magnética , Recidiva , InflamaçãoRESUMO
PURPOSE OF REVIEW: Myelin water imaging (MWI) is generally regarded as the most rigorous approach for noninvasive, in-vivo measurement of myelin content, which has been histopathologically validated. As such, it has been increasingly applied to neurological diseases with white matter involvement, especially those affecting myelin. This review provides an overview of the most recent research applying MWI in neurological syndromes. RECENT FINDINGS: Myelin water imaging has been applied in neurological syndromes including multiple sclerosis, Alzheimer's disease, Huntington's disease, traumatic brain injury, Parkinson's disease, cerebral small vessel disease, leukodystrophies and HIV. These syndromes generally showed alterations observable with MWI, with decreased myelin content tending to correlate with lower cognitive scores and worse clinical presentation. MWI has also been correlated with genetic variation in the APOE and PLP1 genes, demonstrating genetic factors related to myelin health. SUMMARY: MWI can detect and quantify changes not observable with conventional imaging, thereby providing insight into the pathophysiology and disease mechanisms of a diverse range of neurological syndromes.
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Doenças Desmielinizantes , Substância Branca , Encéfalo , Doenças Desmielinizantes/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética/métodos , Bainha de Mielina , Síndrome , ÁguaRESUMO
OBJECTIVES: To analyze work productivity loss and costs, including absenteeism (time missed from work), presenteeism (reduced productivity while working), and unpaid work loss, among a sample of employed people with multiple sclerosis (pwMS) in Canada, as well as its association with clinical, sociodemographic, and work-related factors. METHODS: We used cross-sectional data collected as part of the Canadian Prospective Cohort Study to Understand Progression in MS (CanProCo) and information from the Valuation of Lost Productivity questionnaire. RESULTS: Among 512 pwMS who were employed, 97% showed no or mild disability and 55% experienced productivity loss due to MS in the prior 3 months. Total productivity time loss over a 3-month period averaged 60 hours (SD = 107; 23 from presenteeism, 19 from absenteeism, and 18 from unpaid work), leading to a mean cost of lost productivity of CAD$2480 (SD = 4282) per patient, with an hourly paid productivity loss greater than the wage loss. Fatigue retained significant associations with all productivity loss outcomes. CONCLUSION: Unpaid work loss and productivity losses exceeding those of the employee alone (due to teamwork and associated factors) are key additional contributors of the high economic burden of MS. Workplace accommodations and treatments targeted at fatigue could lessen the economic impact of MS.
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Esclerose Múltipla , Canadá , Estudos Transversais , Fadiga , Humanos , Estudos ProspectivosRESUMO
BACKGROUND: In multiple sclerosis (MS), thalamic integrity is affected directly by demyelination and neuronal loss, and indirectly by gray/white matter lesions outside the thalamus, altering thalamic neuronal projections. OBJECTIVE: To assess the efficacy of ocrelizumab compared with interferon beta-1a (IFNß1a)/placebo on thalamic volume loss and the effect of switching to ocrelizumab on volume change in the Phase III trials in relapsing MS (RMS, OPERA I/II; NCT01247324/NCT01412333) and in primary progressive MS (PPMS, ORATORIO; NCT01194570). METHODS: Thalamic volume change was computed using paired Jacobian integration and analyzed using an adjusted mixed-effects repeated measurement model. RESULTS: Over the double-blind period, ocrelizumab treatment significantly reduced thalamic volume loss with the largest effect size (Cohen's d: RMS: 0.561 at week 96; PPMS: 0.427 at week 120) compared with whole brain, cortical gray matter, and white matter volume loss. At the end of up to 7 years of follow-up, patients initially randomized to ocrelizumab still showed less thalamic volume loss than those switching from IFNß1a (p < 0.001) or placebo (p < 0.001). CONCLUSION: Ocrelizumab effectively reduced thalamic volume loss compared with IFNß1a/placebo. Early treatment effects on thalamic tissue preservation persisted over time. Thalamic volume loss could be a potential sensitive marker of persisting tissue damage.
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Esclerose Múltipla Recidivante-Remitente , Esclerose Múltipla , Anticorpos Monoclonais Humanizados/farmacologia , Anticorpos Monoclonais Humanizados/uso terapêutico , Ensaios Clínicos Fase III como Assunto , Método Duplo-Cego , Humanos , Fatores Imunológicos/farmacologia , Fatores Imunológicos/uso terapêutico , Interferon beta-1a/uso terapêutico , Imageamento por Ressonância Magnética , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
BACKGROUND: Advanced magnetic resonance imaging (MRI) methods can provide more specific information about various microstructural tissue changes in multiple sclerosis (MS) brain. Quantitative measurement of T1 and T2 relaxation, and diffusion basis spectrum imaging (DBSI) yield metrics related to the pathology of neuroinflammation and neurodegeneration that occurs across the spectrum of MS. OBJECTIVE: To use relaxation and DBSI MRI metrics to describe measures of neuroinflammation, myelin and axons in different MS subtypes. METHODS: 103 participants (20 clinically isolated syndrome (CIS), 33 relapsing-remitting MS (RRMS), 30 secondary progressive MS and 20 primary progressive MS) underwent quantitative T1, T2, DBSI and conventional 3T MRI. Whole brain, normal-appearing white matter, lesion and corpus callosum MRI metrics were compared across MS subtypes. RESULTS: A gradation of MRI metric values was seen from CIS to RRMS to progressive MS. RRMS demonstrated large oedema-related differences, while progressive MS had the most extensive abnormalities in myelin and axonal measures. CONCLUSION: Relaxation and DBSI-derived MRI measures show differences between MS subtypes related to the severity and composition of underlying tissue damage. RRMS showed oedema, demyelination and axonal loss compared with CIS. Progressive MS had even more evidence of increased oedema, demyelination and axonal loss compared with CIS and RRMS.
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Esclerose Múltipla Crônica Progressiva , Esclerose Múltipla Recidivante-Remitente , Esclerose Múltipla , Substância Branca , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Imagem de Difusão por Ressonância Magnética/métodos , Humanos , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico por imagem , Esclerose Múltipla/patologia , Esclerose Múltipla Crônica Progressiva/diagnóstico por imagem , Esclerose Múltipla Crônica Progressiva/patologia , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Esclerose Múltipla Recidivante-Remitente/patologia , Doenças Neuroinflamatórias , Substância Branca/diagnóstico por imagem , Substância Branca/patologiaRESUMO
BACKGROUND: Myelin water imaging (MWI) was recently optimized to provide quantitative in vivo measurement of spinal cord myelin, which is critically involved in multiple sclerosis (MS) disability. OBJECTIVE: To assess cervical cord myelin measurements in relapsing-remitting multiple sclerosis (RRMS) and progressive multiple sclerosis (ProgMS) participants and evaluate the correlation between myelin measures and clinical disability. METHODS: We used MWI data from 35 RRMS, 30 ProgMS, and 28 healthy control (HC) participants collected at cord level C2/C3 on a 3 T magnetic resonance imaging (MRI) scanner. Myelin heterogeneity index (MHI), a measurement of myelin variability, was calculated for whole cervical cord, global white matter, dorsal column, lateral and ventral funiculi. Correlations were assessed between MHI and Expanded Disability Status Scale (EDSS), 9-Hole Peg Test (9HPT), timed 25-foot walk, and disease duration. RESULTS: In various regions of the cervical cord, ProgMS MHI was higher compared to HC (between 9.5% and 31%, p ⩽ 0.04) and RRMS (between 13% and 26%, p ⩽ 0.02), and ProgMS MHI was associated with EDSS (r = 0.42-0.52) and 9HPT (r = 0.45-0.52). CONCLUSION: Myelin abnormalities within clinically eloquent areas are related to clinical disability. MWI metrics have a potential role for monitoring subclinical disease progression and adjudicating treatment efficacy for new therapies targeting ProgMS.
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Medula Cervical , Esclerose Múltipla Crônica Progressiva , Esclerose Múltipla Recidivante-Remitente , Esclerose Múltipla , Medula Cervical/diagnóstico por imagem , Avaliação da Deficiência , Humanos , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico por imagem , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Bainha de Mielina , Medula EspinalRESUMO
BACKGROUND: Neurological disability progression occurs across the spectrum of people living with multiple sclerosis (MS). Although there are a handful of disease-modifying treatments approved for use in progressive phenotypes of MS, there are no treatments that substantially modify the course of clinical progression in MS. Characterizing the determinants of clinical progression can inform the development of novel therapeutic agents and treatment approaches that target progression in MS, which is one of the greatest unmet needs in clinical practice. Canada, having one of the world's highest rates of MS and a publicly-funded health care system, represents an optimal country to achieve in-depth analysis of progression. Accordingly, the overarching aim of the Canadian Prospective Cohort Study to Understand Progression in MS (CanProCo) is to evaluate a wide spectrum of factors associated with the clinical onset and rate of disease progression in MS, and to describe how these factors relate to one another to influence progression. METHODS: CanProCo is a prospective, observational cohort study with investigators specializing in epidemiology, neuroimaging, neuroimmunology, health services research and health economics. CanProCo's study design was approved by an international review panel, comprised of content experts and key stakeholders. One thousand individuals with radiologically-isolated syndrome, relapsing-remitting MS, and primary-progressive MS within 10-15 years of disease onset will be recruited from 5 academic MS centres in Canada. Participants will undergo detailed clinical evaluation annually over 5 years (including advanced, app-based clinical data collection). In a subset of participants within 5-10 years of disease onset (n = 500), blood, cerebrospinal fluid, and research MRIs will be collected allowing an integrated, in-depth evaluation of factors contributing to progression in MS from multiple perspectives. Factors of interest range from biological measures (e.g. single-cell RNA-sequencing), MRI-based microstructural assessment, participant characteristics (self-reported, performance-based, clinician-assessed, health-system based), and micro and macro-environmental factors. DISCUSSION: Halting the progression of MS remains a fundamental need to improve the lives of people living with MS. Achieving this requires leveraging transdisciplinary approaches to better characterize why clinical progression occurs. CanProCo is a pioneering multi-dimensional cohort study aiming to characterize these determinants to inform the development and implementation of efficacious and effective interventions.
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Esclerose Múltipla Crônica Progressiva , Esclerose Múltipla , Canadá , Estudos de Coortes , Humanos , Esclerose Múltipla/diagnóstico por imagem , Esclerose Múltipla/epidemiologia , Esclerose Múltipla/terapia , Estudos ProspectivosRESUMO
PURPOSE: Based on a deep learning neural network (NN) algorithm, a super fast and easy to implement data analysis method was proposed for myelin water imaging (MWI) to calculate the myelin water fraction (MWF). METHODS: A NN was constructed and trained on MWI data acquired by a 32-echo 3D gradient and spin echo (GRASE) sequence. Ground truth labels were created by regularized non-negative least squares (NNLS) with stimulated echo corrections. Voxel-wise GRASE data from 5 brains (4 healthy, 1 multiple sclerosis (MS)) were used for NN training. The trained NN was tested on 2 healthy brains, 1 MS brain with segmented lesions, 1 healthy spinal cord, and 1 healthy brain acquired from a different scanner. RESULTS: Production of whole brain MWF maps in approximately 33 âs can be achieved by a trained NN without graphics card acceleration. For all testing regions, no visual differences between NN and NNLS MWF maps were observed, and no obvious regional biases were found. Quantitatively, all voxels exhibited excellent agreement between NN and NNLS (all R2>0.98, p â< â0.001, mean absolute error <0.01). CONCLUSION: The time for accurate MWF calculation can be dramatically reduced to less than 1 âmin by the proposed NN, addressing one of the barriers facing future clinical feasibility of MWI.
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Água Corporal/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Aprendizado Profundo , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla/diagnóstico por imagem , Bainha de Mielina , Neuroimagem/métodos , Adulto , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
PURPOSE: To compare the silent rotating ultrafast imaging sequence (RUFIS) to a traditional Cartesian spoiled gradient-echo (SPGR) acquisition scheme for variable flip angle (VFA) T1 mapping. METHODS: A two-point VFA measurement was performed using RUFIS and Cartesian SPGR in a quantitative phantom and healthy volunteers. To correct for B1 errors, a novel silent magnetization prepared B1 map acquisition (SIMBA) was developed, which combined with RUFIS VFA allows for a completely silent T1 mapping protocol. RESULTS: The silent protocol was found to have comparable repeatability but higher reproducibility in vivo compared to the standard SPGR protocol, and showed no increase in acoustic noise levels above background noise levels compared to a 33 dBA increase for the SPGR acquisition. CONCLUSIONS: VFA T1 mapping using RUFIS is a feasible alternative to SPGR, achieving silent T1 mapping with comparable acquisition time.
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Encéfalo , Imageamento por Ressonância Magnética , Algoritmos , Voluntários Saudáveis , Humanos , Imagens de Fantasmas , Reprodutibilidade dos TestesRESUMO
PURPOSE: Myelin water imaging (MWI) provides a valuable biomarker for myelin, but clinical application has been restricted by long acquisition times. Accelerating the standard multi-echo T2 acquisition with gradient echoes (GRASE) or by 2D multi-slice data collection results in image blurring, contrast changes, and other issues. Compressed sensing (CS) can vastly accelerate conventional MRI. In this work, we assessed the use of CS for in vivo human MWI, using a 3D multi spin-echo sequence. METHODS: We implemented multi-echo T2 relaxation imaging with compressed sensing (METRICS) and METRICS with partial Fourier acceleration (METRICS-PF). Scan-rescan data were acquired from 12 healthy controls for assessment of repeatability. MWI data were acquired for METRICS in 9 m:58 s and for METRICS-PF in 7 m:25 s, both with 1.5 × 2 × 3 mm3 voxels, 56 echoes, 7 ms ΔTE, and 240 × 240 × 170 mm3 FOV. METRICS was compared with a novel multi-echo spin-echo gold-standard (MSE-GS) MWI acquisition, acquired for a single additional subject in 2 h:2 m:40 s. RESULTS: METRICS/METRICS-PF myelin water fraction had mean: repeatability coefficient 1.5/1.1, coefficient of variation 6.2/4.5%, and intra-class correlation coefficient 0.79/0.84. Repeatability metrics comparing METRICS with METRICS-PF were similar, and both sequences agreed with reference values from literature. METRICS images and quantitative maps showed excellent qualitative agreement with those of MSE-GS. CONCLUSION: METRICS and METRICS-PF provided highly repeatable MWI data without the inherent disadvantages of GRASE or 2D multi-slice acquisition. CS acceleration allows MWI data to be acquired rapidly with larger FOV, higher estimated SNR, more isotropic voxels and more echoes than with previous techniques. The approach introduced here generalizes to any multi-component T2 mapping application.
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Processamento de Imagem Assistida por Computador , Bainha de Mielina , Benchmarking , Humanos , Imageamento por Ressonância Magnética , ÁguaRESUMO
Quantitative magnetic resonance imaging (MRI) techniques have been developed as imaging biomarkers, aiming to improve the specificity of MRI to underlying pathology compared to conventional weighted MRI. For assessing the integrity of white matter (WM), myelin, in particular, several techniques have been proposed and investigated individually. However, comparisons between these methods are lacking. In this study, we compared four established myelin-sensitive MRI techniques in 56 patients with relapsing-remitting multiple sclerosis (MS) and 38 healthy controls. We used T2-relaxation with combined GRadient And Spin Echoes (GRASE) to measure myelin water fraction (MWF-G), multi-component driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) to measure MWF-D, magnetization-transfer imaging to measure magnetization-transfer ratio (MTR), and T1 relaxation to measure quantitative T1 (qT1 ). Using voxelwise Spearman correlations, we tested the correspondence of methods throughout the brain. All four methods showed associations that varied across tissue types; the highest correlations were found between MWF-D and qT1 (median ρ across tissue classes 0.8) and MWF-G and MWF-D (median ρ = 0.59). In eight WM tracts, all measures showed differences (p < 0.05) between MS normal-appearing WM and healthy control WM, with qT1 showing the highest number of different regions (8), followed by MWF-D and MTR (6), and MWF-G (n = 4). Comparing the methods in terms of their statistical sensitivity to MS lesions in WM, MWF-D demonstrated the best accuracy (p < 0.05, after multiple comparison correction). To aid future power analysis, we provide the average and standard deviation volumes of the four techniques, estimated from the healthy control sample.
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Encéfalo/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Bainha de Mielina/fisiologia , Neuroimagem/métodos , Adulto , Encéfalo/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla Recidivante-Remitente/fisiopatologia , Adulto JovemRESUMO
BACKGROUND: Tissue damage in both multiple sclerosis (MS) lesions and normal-appearing white matter (NAWM) are important contributors to disability and progression. Specific aspects of MS pathology can be measured using advanced imaging. Alemtuzumab is a humanised monoclonal antibody targeting CD52 developed for MS treatment. OBJECTIVE: To investigate changes over 2 years of advanced magnetic resonance (MR) metrics in lesions and NAWM of MS patients treated with alemtuzumab. METHODS: A total of 42 relapsing-remitting alemtuzumab-treated MS subjects were scanned for 2 years at 3 T. T1 relaxation, T2 relaxation, diffusion tensor, MR spectroscopy and volumetric sequences were performed. Mean T1 and myelin water fraction (MWF) were determined for stable lesions, new lesions and NAWM. Fractional anisotropy was calculated for the corpus callosum (CC) and N-acetylaspartate (NAA) concentration was determined from a large NAWM voxel. Brain parenchymal fraction (BPF), cortical thickness and CC area were also calculated. RESULTS: No change in any MR measurement was found in lesions or NAWM over 24 months. BPF, cortical thickness and CC area all showed decreases in the first year followed by stability in the second year. CONCLUSION: Advanced MR biomarkers of myelin (MWF) and neuron/axons (NAA) show no change in NAWM over 24 months in alemtuzumab-treated MS participants.
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Alemtuzumab/farmacologia , Progressão da Doença , Fatores Imunológicos/farmacologia , Esclerose Múltipla Recidivante-Remitente , Substância Branca , Adulto , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Esclerose Múltipla Recidivante-Remitente/tratamento farmacológico , Esclerose Múltipla Recidivante-Remitente/patologia , Resultado do Tratamento , Substância Branca/diagnóstico por imagem , Substância Branca/efeitos dos fármacos , Substância Branca/patologiaRESUMO
BACKGROUND: Reduced myelin water fraction (MWF, a marker for myelin), increased geometric mean T2 (ieGMT2, reflecting intra/extracellular water properties), and increased T1 (related to total water content) have been observed in cross-sectional studies of multiple sclerosis (MS) normal-appearing white matter (NAWM). OBJECTIVE: To assess longitudinal changes of magnetic resonance (MR) measures in relapsing-remitting MS (RRMS) brain NAWM. METHODS: A total of 11 subjects with RRMS and 4 controls were scanned on a 3T MRI at baseline and long-term follow-up (LTFU; 3.2-5.8 years) with a 32-echo T2 relaxation and an inversion recovery T1 sequence. For every voxel, MWF, ieGMT2, and T1 were obtained. Mean, peak height, and peak location from NAWM mask-based histograms were determined. RESULTS: In MS subjects, NAWM MWF mean decreased by 8% ( p = 0.0016). No longitudinal changes were measured in T1 or ieGMT2. There was no relationship between change in any MR metric and change in EDSS. Control white matter showed no differences over time in any metric. CONCLUSION: The decreases we observed in MWF suggest that changes in myelin integrity and loss of myelin may be occurring diffusely and over long time periods in the MS brain. The timescale of these changes indicates that chronic, progressive myelin damage is an evolving process occurring over many years.
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Encéfalo/patologia , Esclerose Múltipla Recidivante-Remitente/patologia , Bainha de Mielina/patologia , Substância Branca/patologia , Adulto , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla Recidivante-Remitente/diagnóstico por imagem , Água/análise , Substância Branca/diagnóstico por imagemRESUMO
PURPOSE: Myelin water imaging (MWI) using multi-echo T2 relaxation is a quantitative MRI technique that can be used as an in vivo biomarker for myelin in the central nervous system. MWI using a multi-echo spin echo sequence currently takes more than 20 min to acquire eight axial slices (5 mm thickness) in the cervical spinal cord, making spinal cord MWI impractical for implementation in clinical studies. METHODS: In this study, an accelerated gradient and spin echo sequence (GRASE), previously validated for brain MWI, was adapted for spinal cord MWI. Ten healthy volunteers were scanned with the GRASE sequence (acquisition time 8.5 min) and compared with the multi-echo spin echo sequence (acquisition time 23.5 min). RESULTS: Using region of interest analysis, myelin estimates obtained from the two sequences were found to be in good agreement (mean difference = -0.0092, 95% confidence interval = - 0.0092 ± 0.061; regression slope = 1.01, ρ = 0.9). MWI using GRASE was shown to be highly reproducible with an average coefficient of variation of 6.1%. CONCLUSION: The results from this study show that MWI can be performed in the cervical spinal cord in less than 10 min, allowing for practical implementation in multimodal clinical studies. Magn Reson Med 78:1482-1487, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Proteínas da Mielina/química , Bainha de Mielina/química , Medula Espinal/diagnóstico por imagem , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Processamento de Sinais Assistido por Computador , Água , Adulto JovemRESUMO
The hippocampus has been shown to demonstrate a remarkable degree of plasticity in response to a variety of tasks and experiences. For example, the size of the human hippocampus has been shown to increase in response to aerobic exercise. However, it is currently unknown what underlies these changes. Here we scanned sedentary, young to middle-aged human adults before and after a six-week exercise intervention using nine different neuroimaging measures of brain structure, vasculature, and diffusion. We then tested two different hypotheses regarding the nature of the underlying changes in the tissue. Surprisingly, we found no evidence of a vascular change as has been previously reported. Rather, the pattern of changes is better explained by an increase in myelination. Finally, we show that hippocampal volume increase is temporary, returning to baseline after an additional six weeks without aerobic exercise. This is the first demonstration of a change in hippocampal volume in early to middle adulthood suggesting that hippocampal volume is modulated by aerobic exercise throughout the lifespan rather than only in the presence of age related atrophy. It is also the first demonstration of hippocampal volume change over a period of only six weeks, suggesting that gross morphometric hippocampal plasticity occurs faster than previously thought.
Assuntos
Envelhecimento/fisiologia , Circulação Cerebrovascular/fisiologia , Exercício Físico/fisiologia , Hipocampo/fisiologia , Neuroimagem/métodos , Plasticidade Neuronal/fisiologia , Adulto , Envelhecimento/patologia , Velocidade do Fluxo Sanguíneo/fisiologia , Feminino , Hipocampo/anatomia & histologia , Humanos , Masculino , Imagem Multimodal/métodos , Tamanho do Órgão/fisiologia , Condicionamento Físico Humano/métodosRESUMO
PURPOSE: To determine whether differences in hydration state, which could arise from routine clinical procedures such as overnight fasting, affect brain total water content (TWC) and brain volume measured with magnetic resonance imaging (MRI). MATERIALS AND METHODS: Twenty healthy volunteers were scanned with a 3T MR scanner four times: day 1, baseline scan; day 2, hydrated scan after consuming 3L of water over 12 hours; day 3, dehydrated scan after overnight fasting of 9 hours, followed by another scan 1 hour later for reproducibility. The following MRI data were collected: T2 relaxation (for TWC measurement), inversion recovery (for T1 measurement), and 3D T1 -weighted (for brain volumes). Body weight and urine specific gravity were also measured. TWC was calculated by fitting the T2 relaxation data with a nonnegative least-squares algorithm, with corrections for T1 relaxation and image signal inhomogeneity and normalization to ventricular cerebrospinal fluid. Brain volume changes were measured using SIENA. TWC means were calculated within 14 tissue regions. RESULTS: Despite indications of dehydration as demonstrated by increases in urine specific gravity (P = 0.03) and decreases in body weight (P = 0.001) between hydrated and dehydrated scans, there was no measurable change in TWC (within any brain region) or brain volume between hydration states. CONCLUSION: We demonstrate that within a range of physiologic conditions commonly encountered in routine clinical scans (no pretreatment with hydration, well hydrated before MRI, and overnight fasting), brain TWC and brain volumes are not substantially affected in a healthy control cohort. J. Magn. Reson. Imaging 2016;44:296-304.
Assuntos
Água Corporal/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Imagem de Difusão por Ressonância Magnética/métodos , Ingestão de Líquidos/fisiologia , Jejum/fisiologia , Equilíbrio Hidroeletrolítico/fisiologia , Adulto , Encéfalo/anatomia & histologia , Água Potável , Feminino , Humanos , Imageamento Tridimensional/métodos , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão/fisiologia , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Privação de Água/fisiologiaRESUMO
BACKGROUND: Both multiple sclerosis (MS) and neuromyelitis optica (NMO) can present with transverse myelitis; however, NMO symptoms are usually more severe and may present with more extensive axonal loss. Transcranial magnetic stimulation (TMS)-based input-output recruitment curves can quantitatively assess the excitability of corticospinal tract pathways and myelin water imaging can quantify the amount of myelin within this same pathway. OBJECTIVE: To compare differential effects of MS and NMO on TMS recruitment curves and myelin water imaging. METHODS: Ten healthy controls, 10 individuals with MS and 10 individuals with NMO completed clinical assessments, a TMS assessment and magnetic resonance imaging scan to measure recruitment curves and myelin water fraction in the corticospinal tract. RESULTS: Individuals with NMO had lower recruitment curve slopes (mean 13.6±6 µV/%) than MS (23.6±11 µV/%) and controls (21.9±9 µV/%, analysis of variance (ANOVA) P=0.05). Corticospinal tract myelin water fraction was lower in individuals with NMO (mean 0.17±0.02) compared to MS (0.19±0.02) and controls (0.20±0.02, ANOVA P=0.0006). CONCLUSION: Corticospinal pathway damage in individuals with NMO was evident by reduced recruitment curve slope and lower myelin water fraction. These specific measures of corticospinal function and structure may be used to obtain a better understanding and monitor brain injury caused by inflammatory central nervous system disorders.