Myelin Water Fraction and Intra/Extracellular Water Geometric Mean T<sub>2</sub>Normative Atlases for the Cervical Spinal Cord from 3T MRI

Liu, Hanwen; Ljungberg, Emil; Dvorak, Adam; Lee, Lisa Eunyoung; Yik, Jackie T; MacMillan, Erin L.; Barlow, Laura; Li, David K.B.; Traboulsee, Anthony; Kolind, Shannon; Kramer, John L. K.; Laule, Cornelia

doi:10.1111/jon.12659

Cited by 15 publications

(17 citation statements)

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“…Our findings suggest that, when comparing MWF of individual subjects to a myelin water atlas (58,59), these atlases have to be updated with DTI data. In particular, fiber tracts at angles between 10 • and 40 • , where MWI is most sensitive to changes in tissue orientation, may exhibit paradoxical results if their orientation differs from the average orientation of the tract in the atlas.…”

Section: Discussionmentioning

confidence: 99%

Myelin water imaging depends on white matter fiber orientation in the human brain

Birkl

Doucette

Fan

et al. 2020

Preprint

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The multiexponential T 2 decay of the magnetic resonance imaging (MRI) signal from cerebral white matter can be separated into short components sensitive to myelin water and long components related to intra-and extracellular water. In this study we investigated to what degree the myelin water fraction (MWF) depends on the angle between white matter fibers and the main magnetic filed. Maps of MWF were acquired using multi echo CPMG and GRASE sequences. The CPMG sequence was acquired with a TR of 1073 ms, 1500 ms and 2000 ms. The fiber orientation was mapped with diffusion tensor imaging. By angle-wise pooling the voxels across the brain's white matter, an orientation dependent MWF curve was generated. We found that MWF varied between 25% and 35% across different fiber orientations. The orientation dependency of the MWF is characterized by a dipole-dipole interaction model. Furthermore, the selection of the TR influences the orientation dependent and global white matter MWF. White matter fiber orientation induces a strong systematic bias on the estimation of MWF. This finding has important implications for future research and the interpretation of MWI results in previously published studies.myelin water imaging | fiber orientation | white matter | magic angle | brain | quantitative MRI MethodsEight healthy volunteers (3 female, 5 male) with a mean age of 26 years (age range = 21 -33 years) and without any history of neurological disorder participated in this study, which was approved by the University of British Columbia Clinical Research Ethics Board. All volunteers gave written informed consent. MR imaging was performed on a 3 T MR system (Ingenia Elition, Philips Medical Systems, Best, The Netherlands) using a 32-channel SENSE head coil. MRI acquisition.A 3D T1 weighted sequence with echo time (TE) = 4.9 ms, TR = 9.8 ms, flip angle = 8°, a resolution of 0.8 x 0.8 x 0.8 mm 3 , a compressed SENSE (CS) factor of 3.6 and acquisition time of 5:50 min was acquired for anatomical overview. CS is a combination of compressed sensing (35,36) and SENSE (37). For the calculation of fiber orientation a DTI sequence with TE = 60 ms, TR = 4111 ms, b-value = 700 s/mm 2 , 60 diffusion directions, a resolution of 2.3 x 2.3 x 2.4 mm 3 , multi band factor 2 (38), SENSE factor 2.1 and

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Section: Discussionmentioning

confidence: 99%

Myelin water imaging depends on white matter fiber orientation in the human brain

Birkl

Doucette

Fan

et al. 2020

Preprint

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“…[34][35][36][37][38][39][40][41][42][43][44][45][46][47] Rapid myelination has been demonstrated in early childhood and adolescence using multicomponent driven equilibrium single pulse observation of T 1 and T 2 (mcDESPOT), an alternate approach to MWI using a steadystate acquisition. [48][49][50][51][52][53] Adult multi-echo T 2 -based MWF atlases in both brain and cervical spinal cord have recently been published, 54,55 but, to our knowledge, no such atlases exist for children.…”

Section: Introductionmentioning

confidence: 99%

Brain Myelin Water Fraction and Diffusion Tensor Imaging Atlases for 9‐10 Year‐Old Children

Morris

Holmes

Dvorak

et al. 2020

Journal of Neuroimaging

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BACKGROUND AND PURPOSE Myelin water imaging (MWI) and diffusion tensor imaging (DTI) provide information about myelin and axon‐related brain microstructure, which can be useful for investigating normal brain development and many childhood brain disorders. While pediatric DTI atlases exist, there are no pediatric MWI atlases available for the 9‐10 years old age group. As myelination and structural development occurs throughout childhood and adolescence, studies of pediatric brain pathologies must use age‐specific MWI and DTI healthy control data. We created atlases of myelin water fraction (MWF) and DTI metrics for healthy children aged 9‐10 years for use as normative data in pediatric neuroimaging studies. METHODS 3D‐T1, DTI, and MWI scans were acquired from 20 healthy children (mean age: 9.6 years, range: 9.2‐10.3 years, 4 females). ANTs and FSL registration were used to create quantitative MWF and DTI atlases. Region of interest (ROI) analysis in nine white matter regions was used to compare pediatric MWF with adult MWF values from a recent study and to investigate the correlation between pediatric MWF and DTI metrics. RESULTS Adults had significantly higher MWF than the pediatric cohort in seven of the nine white matter ROIs, but not in the genu of the corpus callosum or the cingulum. In the pediatric data, MWF correlated significantly with mean diffusivity, but not with axial diffusivity, radial diffusivity, or fractional anisotropy. CONCLUSIONS Normative MWF and DTI metrics from a group of 9‐10 year old healthy children provide a resource for comparison to pathologies. The age‐specific atlases are ready for use in pediatric neuroimaging research and can be accessed: https://sourceforge.net/projects/pediatric-mri-myelin-diffusion/.

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“…Post-processing of spinal cord MR data was performed as described by Liu et al (97). Spinal cord segmentation of the GRASE image occurred using the Spinal Cord Toolbox PropSeg tool (98, 99), which generated a mask of the whole cord.…”

Section: Methodsmentioning

confidence: 99%

Eccentric-focused rehabilitation promotes myelin plasticity in individuals with chronic, incomplete spinal cord injury

Faw

Lakhani

Nguyen

et al. 2020

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Background: Myelin plasticity has emerged as a novel mechanism by which the nervous system can change with experience, offering new potential for rehabilitation-induced recovery after neurotrauma. This first-in-human study investigated whether innovative, downhill locomotor rehabilitation promotes myelin plasticity in individuals with chronic, incomplete spinal cord injury (SCI). Methods: Of 20 individuals with SCI that enrolled, 4 passed the imaging screen and had myelin water imaging (MWI) before and after a 12-week (3 times/week) downhill locomotor treadmill training program (SCI+DH). One individual was excluded for imaging artifacts. Uninjured control participants (n=7) had two MWI sessions within the same day. Changes in myelin water fraction (MWF), a histopathologically-validated myelin biomarker, were analyzed in a priori motor learning and non-motor learning brain regions and the cervical spinal cord using statistical approaches appropriate for small sample sizes. Results: Within SCI+DH individuals, significantly more motor learning regions showed increased MWF than non-motor learning regions (p<.05). Compared to Control, MWF in the SCI+DH group increased in white matter underlying postcentral and precuneus cortices, combined motor learning brain regions, and ventral spinal cord (p<.05). To account for small sample size, an estimation-based approach showed the pattern of MWF increase was specific to training and region. Conclusion: Downhill training increased MWF in brain regions specifically associated with motor learning and in the ventral spinal cord. Trial Registration: ClincialTrials.gov (NCT02498548, NCT02821845). Funding: National Institutes of Health [F31NS096921 (TDF), R21HD082808 (DMB)], Craig H. Neilsen Foundation [316282 (DMB)], Foundation for Physical Therapy Research [Promotion of Doctoral Studies Level II Scholarship (TDF)]

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Myelin Water Fraction and Intra/Extracellular Water Geometric Mean T₂Normative Atlases for the Cervical Spinal Cord from 3T MRI

Cited by 15 publications

References 50 publications

Myelin water imaging depends on white matter fiber orientation in the human brain

Myelin water imaging depends on white matter fiber orientation in the human brain

Brain Myelin Water Fraction and Diffusion Tensor Imaging Atlases for 9‐10 Year‐Old Children

Eccentric-focused rehabilitation promotes myelin plasticity in individuals with chronic, incomplete spinal cord injury

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Myelin Water Fraction and Intra/Extracellular Water Geometric Mean T2Normative Atlases for the Cervical Spinal Cord from 3T MRI

Cited by 15 publications

References 50 publications

Myelin water imaging depends on white matter fiber orientation in the human brain

Myelin water imaging depends on white matter fiber orientation in the human brain

Brain Myelin Water Fraction and Diffusion Tensor Imaging Atlases for 9‐10 Year‐Old Children

Eccentric-focused rehabilitation promotes myelin plasticity in individuals with chronic, incomplete spinal cord injury

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Myelin Water Fraction and Intra/Extracellular Water Geometric Mean T₂Normative Atlases for the Cervical Spinal Cord from 3T MRI