Magnetic field and tissue dependencies of human brain longitudinal 1H2O relaxation in vivo

William D. Rooney, Glyn Johnson, Xin Li, Eric R. Cohen, Seong-Gi Kim, Kamil Ugurbil, Charles S. Springer Jr

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Abstract

Brain water proton (1H2O) longitudinal relaxation time constants (T1) were obtained from three healthy individuals at magnetic field strengths (B0) of 0.2 Tesla (T), 1.0T, 1.5T, 4.0T, and 7.0T. A 5-mm midventricular axial slice was sampled using a modified Look-Locker technique with 1.5 mm in-plane resolution, and 32 time points post-adiabatic inversion. The results confirmed that for most brain tissues, T1 values increased by more than a factor of 3 between 0.2T and 7T, and over this range were well fitted by T1 (s)=0.583(B0)0.382, T1(s)=0.857(B0)0.376, and T1(s)=1.35(B0)0.340 for white matter (WM), internal GM, and blood 1H2O, respectively. The ventricular cerebrospinal fluid (CSF) 1H2O T1 value did not change with B0, and its average value (standard deviation (SD)) across subjects and magnetic fields was 4.3 (+/-0.2) s. The tissue 1/T1 values at each field were well correlated with the macromolecular mass fraction, and to a lesser extent tissue iron content. The field-dependent increases in 1H2O T1 values more than offset the well-known decrease in typical MRI contrast reagent (CR) relaxivity, and simulations predict that this leads to lower CR concentration detection thresholds with increased magnetic field.
Original languageUndefined/Unknown
Pages (from-to)308-318
Number of pages11
JournalJournal of Magnetic Resonance Imaging
Volume57
Issue number2
Early online date26 Jan 2007
DOIs
Publication statusPublished - 2007

Keywords

  • Adult Algorithms Body Water
  • metabolism
  • Brain Mapping
  • methods Chi-Square Distribution Humans Image Processing
  • Computer-Assisted Magnetic Resonance Imaging
  • methods Male Middle Aged

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