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Simultaneous T 2 * and diffusion measurements with 3 He
Author(s) -
Bock Michael
Publication year - 1997
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.1910380607
Subject(s) - nuclear magnetic resonance , diffusion , pulse sequence , spin echo , relaxation (psychology) , pulse (music) , physics , magnetic resonance imaging , chemistry , analytical chemistry (journal) , optics , radiology , medicine , psychology , social psychology , chromatography , detector , thermodynamics
It has recently been demonstrated that magnetic resonance (MR) imaging of human lungs and airways is possible with hyperpolarized gases such as 3 He. Because the influence of the apparent transversal relaxation ( T 2 * decay) and diffusion in 3 He imaging have not been quantified, an imaging pulse sequence was developed to measure these two parameters simultaneously. The imaging pulse sequence generates two series of multiply recalled gradient echo images with both different echo‐spacings and diffusion‐sensitizing gradients. From differences in exponential signal decay between the two series, T 2 * and diffusion coefficients, D , of both hyperpolarized and unpolarized 3 He samples could be measured on a standard clinical imager using a home‐built Helmholtz coil. In a hyperpolarized sample of pure 3 He values of D = (1.8 ± 0.2) ± 10 −4 m 2 /s and T 2 * = 36 ± 13 ms were measured, while D = (0.3 ± 0.1) · 10 −4 m 2 /s and T 2 * = 136 ± 66 ms were found in a Boltzmann‐polarized 3 He/O 2 mixture.