The in vivo influence of white matter fiber orientation towards B0 on T2 in the human brain

It is well known that, at higher field strength, T2*‐weighted images show an extensive heterogeneity in white matter fiber bundles. The basis of this phenomenon is still under discussion, as many factors, such as iron concentration, myelination and tissue microstructure, could influence relaxation t...

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Bibliographic Details
Published in:NMR in biomedicine 2010-11, Vol.23 (9), p.1071-1076
Main Authors: Bender, B., Klose, U.
Format: Article
Language:English
Subjects:
Brain
DTI
fiber orientation
Fibers
Head
Iron
Magnetic fields
Magnetic resonance imaging
Myelination
N.M.R
relaxation time
Substantia alba
white matter
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Summary:It is well known that, at higher field strength, T2*‐weighted images show an extensive heterogeneity in white matter fiber bundles. The basis of this phenomenon is still under discussion, as many factors, such as iron concentration, myelination and tissue microstructure, could influence relaxation times. Furthermore, fiber direction in relation to the main magnetic field seems to influence T2* relaxation times. In this study, diffusion tensor imaging and T2* measurements were combined in seven subjects with the head in a normal and tilted position. It was shown that fiber orientation has a strong influence on T2* in the human brain, with the average T2* value changing from 49 ms for a perpendicular orientation to B0 to 57 ms for a parallel orientation to B0. Nevertheless, T2* times showed a wide variety of values at any orientation towards B0. Copyright © 2010 John Wiley & Sons, Ltd. The z component of the fiber orientation describes the orientation towards B0. A sin2 relationship between the z component of the fiber orientation and T2* was found. No influence of the x and y components on T2* could be detected.
ISSN:0952-3480
1099-1492
1099-1492
DOI:10.1002/nbm.1534