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Diffusion imaging of the human brain in vivo using high‐speed STEAM MRI
Author(s) -
Merboldt KlausDietmar,
Hänicke Wolfgang,
Bruhn Harald,
Gyngell Michael L.,
Frahm Jens
Publication year - 1992
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.1910230119
Subject(s) - white matter , diffusion mri , nuclear magnetic resonance , diffusion , imaging phantom , diffusion imaging , physics , chemistry , materials science , nuclear medicine , biomedical engineering , magnetic resonance imaging , optics , medicine , radiology , thermodynamics
This paper describes a new method for diffusion imaging of the human brain in vivo that is based on a combination of diffusion‐encoding gradients with high‐speed STEAM MR imaging. The single‐shot sequence 90°‐TE/2‐90°‐TM‐(α‐TE/2‐STE) n generates n = 32–64 differently phase‐encoded stimulated echoes STE yielding image acquisition times of 576 ms for a 48 ×128 data matrix. Diffusion encoding is performed during the first TE/2‐interval as well as during each readout period. Phantom studies reveal a quantitative agreement of calculated diffusion coefficients with literature values. EKG triggering completely eliminates motion artifacts from diffusion‐weighted single‐shot STEAM images of human brain in vivo. While signal attenuation of the cerebrospinal fluid (CSF) is predominantly due to flow, that observed for gray and white matter results from diffusion. Evaluated diffusion coefficients yield (1.0 ± 0.1) × 10 −5 cm 2 s −1 for gray matter, (0.5 ± 0.1) × 10 −5 cm 2 s −1 for white matter with the diffusion encoding parallel to the main orientation of the myelin sheath of the neurofibrils, and (0.3 ± 0.1) × 10 −5 cm 2 s −1 for white matter and a perpendicular orientation. All studies were performed at 2.0 T using a conventional 10 mT m −1 gradient system. © 1992 Academic Press, Inc.