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Proton <i>T</i><sub>2</sub> relaxation study of water, N‐acetylaspartate, and creatine in human brain using Hahn and Carr‐Purcell spin echoes at 4T and 7T

Shalom Michaeli, Michael Garwood, Xiaohong Zhu, Lance DelaBarre, Peter Andersen, Gregor Adriany, Hellmut Merkle, Kǎmil Uǧurbil, Wei Chen

Magnetic Resonance in Medicine · 2002 · 199 citations · 29 references

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TL;DR

The study employed Carr‑Purcell and Hahn spin‑echo sequences to measure the apparent transverse relaxation time (T2) of water and metabolites in the human brain at 4 T and 7 T, noting that Carr‑Purcell sequences mitigate signal loss at high field. Increasing magnetic field strength from 4 T to 7 T significantly reduced the T2 values of water, N‑acetylaspartate, and creatine/phosphocreatine, mainly due to enhanced dynamic dephasing from larger local susceptibility gradients. Published in Magn Reson Med.

Abstract

Abstract Carr‐Purcell and Hahn spin‐echo (SE) measurements were used to estimate the apparent transverse relaxation time constant ( T ) of water and metabolites in human brain at 4T and 7T. A significant reduction in the T 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 T decay can be substantially reduced using a Carr‐Purcell‐type SE sequence. Magn Reson Med 47:629–633, 2002. © 2002 Wiley‐Liss, Inc.