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Keywords:

  • T2 relaxation time;
  • high magnetic field;
  • Carr-Purcell spin echo;
  • cerebral metabolites;
  • adiabatic pulse

Abstract

Carr-Purcell and Hahn spin-echo (SE) measurements were used to estimate the apparent transverse relaxation time constant (Tmath image) of water and metabolites in human brain at 4T and 7T. A significant reduction in the Tmath image values of proton resonances (water, N-acetylaspartate, and creatine/phosphocreatine) was observed with increasing magnetic field strength and was attributed mainly to increased dynamic dephasing due to increased local susceptibility gradients. At high field, signal loss resulting from Tmath image decay can be substantially reduced using a Carr-Purcell-type SE sequence. Magn Reson Med 47:629–633, 2002. © 2002 Wiley-Liss, Inc.