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In vivo diffusion tensor imaging of human calf muscle
Author(s) -
Sinha Usha,
Yao Lawrence
Publication year - 2002
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.10035
Subject(s) - diffusion mri , anisotropy , anisotropic diffusion , diagonal , diffusion , signal to noise ratio (imaging) , tensor (intrinsic definition) , nuclear magnetic resonance , physics , mathematics , materials science , biomedical engineering , optics , magnetic resonance imaging , geometry , medicine , radiology , thermodynamics
Abstract Purpose To investigate a tetrahedral diffusion gradient encoding scheme to measure the diffusion tensor in vivo for human calf muscle. Materials and Methods The theoretical TE which maximizes the signal‐to‐noise ratio (SNR) of the diffusion images was derived for both the orthogonal and tetrahedral sampling strategies and the SNR advantage verified experimentally. A diffusion echo‐planar imaging (EPI) sequence was used to image five volunteers. Gradient cycling and geometric averaging was performed to eliminate cross‐terms between the imaging and diffusion gradients. Results Trace diffusion coefficients in human muscle are spatially invariant and have low intersubject variability (<4%). Images of the off‐diagonal terms confirm the anisotropy of muscle, and fiber orientation maps were derived from these off‐diagonal images. A noninvariant index of anisotropy, A ratio (average value: 1.28), was found to be less susceptible to noise than the invariant index. Conclusion This technique is robust and can be readily implemented on clinical scanners with EPI capabilities. J. Magn. Reson. Imaging 2002;15:87–95. © 2002 Wiley‐Liss, Inc.