Longitudinal changes in advanced diffusion MRI of normal-appearing white matter and chronic lesions in ocrelizumab treated relapsing MS

2018 ◽  
Author(s):  
Anika Wurl ◽  
Irene M. Vavasour
Keyword(s):  
White Matter ◽  
Diffusion Mri ◽  
Longitudinal Changes ◽  
Normal Appearing White Matter

scholarly journals Disentangling white-matter damage from physiological fibre orientation dispersion in multiple sclerosis

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Kasper Winther Andersen ◽  
Samo Lasič ◽  
Henrik Lundell ◽  
Markus Nilsson ◽  
Daniel Topgaard ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Fractional Anisotropy ◽  
Diffusion Mri ◽  
Fibre Orientation ◽  
Cerebral White Matter ◽  
Healthy Controls ◽  
Lesion Load ◽  
Normal Appearing White Matter ◽  
Relapsing Remitting

Abstract Multiple sclerosis leads to diffuse damage of the central nervous system, affecting also the normal-appearing white matter. Demyelination and axonal degeneration reduce regional fractional anisotropy in normal-appearing white matter, which can be routinely mapped with diffusion tensor imaging. However, the standard fractional anisotropy metric is also sensitive to physiological variations in orientation dispersion of white matter fibres. This complicates the detection of disease-related damage in large parts of cerebral white matter where microstructure physiologically displays a high degree of fibre dispersion. To resolve this ambiguity, we employed a novel tensor-valued encoding method for diffusion MRI, which yields a microscopic fractional anisotropy metric that is unaffected by regional variations in orientation dispersion. In 26 patients with relapsing-remitting multiple sclerosis, 14 patients with primary-progressive multiple sclerosis and 27 age-matched healthy controls, we compared standard fractional anisotropy mapping with the novel microscopic fractional anisotropy mapping method, focusing on normal-appearing white matter. Mean microscopic fractional anisotropy and standard fractional anisotropy of normal-appearing white matter were significantly reduced in both patient groups relative to healthy controls, but microscopic fractional anisotropy yielded a better reflection of disease-related white-matter alterations. The reduction in mean microscopic fractional anisotropy showed a significant positive linear relationship with physical disability, as reflected by the expanded disability status scale. Mean reduction of microscopic fractional anisotropy in normal-appearing white matter also scaled positively with individual cognitive dysfunction, as measured with the symbol digit modality test. Mean microscopic fractional anisotropy reduction in normal-appearing white matter also showed a positive relationship with total white-matter lesion load as well as lesion load in specific tract systems. None of these relationships between normal-appearing white-matter microstructure and clinical, cognitive or structural measures emerged when using mean fractional anisotropy. Together, the results provide converging evidence that microscopic fractional anisotropy mapping substantially advances the assessment of cerebral white matter in multiple sclerosis by disentangling microstructure damage from variations in physiological fibre orientation dispersion at the stage of data acquisition. Since tensor-valued encoding can be implemented in routine diffusion MRI, microscopic fractional anisotropy mapping bears considerable potential for the future assessment of disease progression in normal-appearing white matter in both relapsing-remitting and progressive forms of multiple sclerosis as well as other white-matter-related brain diseases.

Global loss of myelin water over 5 years in multiple sclerosis normal-appearing white matter

2017 ◽  
Vol 24 (12) ◽  
pp. 1557-1568 ◽  
Author(s):  
Irene M Vavasour ◽  
Sophie C Huijskens ◽  
David KB Li ◽  
Anthony L Traboulsee ◽  
Burkhard Mädler ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Geometric Mean ◽  
Peak Height ◽  
Cross Sectional ◽  
Longitudinal Changes ◽  
Water Fraction ◽  
Normal Appearing White Matter ◽  
Long Term Follow Up ◽  
Long Time

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.

scholarly journals Improving Spatial Normalization of Brain Diffusion MRI to Measure Longitudinal Changes of Tissue Microstructure in the Cortex and White Matter

2020 ◽  
Vol 52 (3) ◽  
pp. 766-775 ◽  
Author(s):  
Florencia Jacobacci ◽  
Jorge Jovicich ◽  
Gonzalo Lerner ◽  
Edson Amaro ◽  
Jorge L. Armony ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Mri ◽  
Spatial Normalization ◽  
Tissue Microstructure ◽  
Longitudinal Changes

Clustering of short association white matter fibers calculated from diffusion MRI

2014 ◽  
Author(s):  
C. Roman ◽  
D. Le Bihan ◽  
C. Poupon ◽  
P. Guevara ◽  
A. Lebois ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Mri

scholarly journals Functional and diffusion MRI reveal the neurophysiological basis of neonates’ noxious-stimulus evoked brain activity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Luke Baxter ◽  
Fiona Moultrie ◽  
Sean Fitzgibbon ◽  
Marianne Aspbury ◽  
Roshni Mansfield ◽  
...  
Keyword(s):  
White Matter ◽  
Prediction Model ◽  
Resting State ◽  
Early Life ◽  
Diffusion Mri ◽  
Brain Activity ◽  
Noxious Stimulus ◽  
Noxious Stimulation ◽  
Human Connectome Project ◽  
And Diffusion

AbstractUnderstanding the neurophysiology underlying neonatal responses to noxious stimulation is central to improving early life pain management. In this neonatal multimodal MRI study, we use resting-state and diffusion MRI to investigate inter-individual variability in noxious-stimulus evoked brain activity. We observe that cerebral haemodynamic responses to experimental noxious stimulation can be predicted from separately acquired resting-state brain activity (n = 18). Applying this prediction model to independent Developing Human Connectome Project data (n = 215), we identify negative associations between predicted noxious-stimulus evoked responses and white matter mean diffusivity. These associations are subsequently confirmed in the original noxious stimulation paradigm dataset, validating the prediction model. Here, we observe that noxious-stimulus evoked brain activity in healthy neonates is coupled to resting-state activity and white matter microstructure, that neural features can be used to predict responses to noxious stimulation, and that the dHCP dataset could be utilised for future exploratory research of early life pain system neurophysiology.

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