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Characterization of T 2 * heterogeneity in human brain white matter
Author(s) -
Li TieQiang,
Yao Bing,
van Gelderen Peter,
Merkle Hellmut,
Dodd Stephen,
Talagala Lalith,
Koretsky Alan P.,
Duyn Jeff
Publication year - 2009
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22156
Subject(s) - white matter , human brain , myelin , nuclear magnetic resonance , pathology , relaxometry , chemistry , magnetic resonance imaging , biology , medicine , central nervous system , spin echo , physics , neuroscience , radiology
Recent in vivo MRI studies at 7.0 T have demonstrated extensive heterogeneity of T 2 * relaxation in white matter of the human brain. In order to study the origin of this heterogeneity, we performed T 2 * measurements at 1.5, 3.0, and 7.0 T in normal volunteers. Formalin‐fixed brain tissue specimens were also studied using T 2 *‐weighted MRI, histologic staining, chemical analysis, and electron microscopy. We found that T 2 * relaxation rate ( R 2 * = 1/ T 2 *) in white matter in living human brain is linearly dependent on the main magnetic field strength, and the T 2 * heterogeneity in white matter observed at 7.0 T can also be detected, albeit more weakly, at 1.5 and 3.0 T. The T 2 * heterogeneity exists also in white matter of the formalin‐fixed brain tissue specimens, with prominent differences between the major fiber bundles such as the cingulum (CG) and the superior corona radiata. The white matter specimen with substantial difference in T 2 * has no significant difference in the total iron content, as determined by chemical analysis. On the other hand, evidence from histologic staining and electron microscopy demonstrates these tissue specimens have apparent difference in myelin content and microstructure. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.