Nonexponential T2* decay in white matter

Peter Van Gelderen, Jacco A. De Zwart, Jongho Lee, Pascal Sati, Daniel S. Reich, Jeff H. Duyn

Research output: Contribution to journalArticlepeer-review

Abstract

Visualizing myelin in human brain may help the study of diseases such as multiple sclerosis. Previous studies based on T1 and T2 relaxation contrast have suggested the presence of a distinct water pool that may report directly on local myelin content. Recent work indicates that T 2* contrast may offer particular advantages over T1 and T2 contrast, especially at high field. However, the complex mechanism underlying T2* relaxation may render interpretation difficult. To address this issue, T2* relaxation behavior in human brain was studied at 3 and 7 T. Multiple gradient echoes covering most of the decay curve were analyzed for deviations from mono-exponential behavior. The data confirm the previous finding of a distinct rapidly relaxing signal component (T2* ∼ 6 ms), tentatively attributed to myelin water. However, in extension to previous findings, this rapidly relaxing component displayed a substantial resonance frequency shift, reaching 36 Hz in the corpus callosum at 7 T. The component's fractional amplitude and frequency shift appeared to depend on both field strength and fiber orientation, consistent with a mechanism originating from magnetic susceptibility effects. The findings suggest that T2* contrast at high field may be uniquely sensitive to tissue myelin content and that proper interpretation will require modeling of susceptibility-induced resonance frequency shifts.

Original languageEnglish (US)
Pages (from-to)110-117
Number of pages8
JournalMagnetic resonance in medicine
Volume67
Issue number1
DOIs
StatePublished - Jan 2012

Keywords

  • high field imaging
  • myelin water fraction
  • relaxation
  • white matter imaging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Fingerprint Dive into the research topics of 'Nonexponential T<sub>2</sub>* decay in white matter'. Together they form a unique fingerprint.

Cite this