Myelin water imaging depends on white matter fiber orientation in the human brain
Purpose The multi‐exponential T2 decay of the MRI signal from cerebral white matter can be separated into short T2 components related to myelin water and long T2 components related to intracellular and extracellular water. In this study, we investigated to what degree the apparent myelin water fract...
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Published in | Magnetic resonance in medicine Vol. 85; no. 4; pp. 2221 - 2231 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Wiley Subscription Services, Inc
01.04.2021
John Wiley and Sons Inc |
Subjects | |
Online Access | Get full text |
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Summary: | Purpose
The multi‐exponential T2 decay of the MRI signal from cerebral white matter can be separated into short T2 components related to myelin water and long T2 components related to intracellular and extracellular water. In this study, we investigated to what degree the apparent myelin water fraction (MWF) depends on the angle between white matter fibers and the main magnetic field.
Methods
Maps of the apparent MWF were acquired using multi‐echo Carr‐Purcell‐Meiboom‐Gill and gradient‐echo spin‐echo sequences. The Carr‐Purcell‐Meiboom‐Gill sequence was acquired with a TR of 1073 ms, 1500 ms, and 2000 ms. The fiber orientation was mapped with DTI. By angle‐wise pooling the voxels across the brain’s white matter, orientation‐dependent apparent MWF curves were generated.
Results
We found that the apparent MWF varied between 25% and 35% across different fiber orientations. Furthermore, the selection of the TR influences the apparent MWF.
Conclusion
White matter fiber orientation induces a strong systematic bias on the estimation of the apparent MWF. This finding has implications for future research and the interpretation of MWI results in previously published studies. |
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Bibliography: | Funding information Austrian Science Fund (FWF project number J 4038); the National MS Society (RG 1507 05301); the Natural Sciences and Engineering Research Council of Canada (016‐05371); the Canadian Institutes of Health Research (RN382474‐418628); and the Canada Research Chairs (950‐230363 to A.R.) ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0740-3194 1522-2594 |
DOI: | 10.1002/mrm.28543 |