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Mapping fiber orientation in human muscle by proton MR spectroscopic imaging
Author(s) -
Vermathen Peter,
Boesch Chris,
Kreis Roland
Publication year - 2003
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.10396
Subject(s) - nuclear magnetic resonance , phosphocreatine , creatine , orientation (vector space) , magnetic resonance imaging , metabolite , chemistry , sagittal plane , muscle fibre , fiber , anatomy , physics , skeletal muscle , medicine , geometry , mathematics , biochemistry , organic chemistry , radiology , energy metabolism
Proton magnetic resonance spectroscopic imaging ( 1 H‐MRSI) was used to determine muscle fiber orientations in human calf muscles. The method is based on the fact that some resonances show orientation‐dependent dipolar splitting, caused by incomplete motional averaging. This leads to proton spectra that depend strongly on the angle between muscle fibers and the magnetic field B 0 . The orientation‐dependent dipolar splittings were mapped using a fit with a basis set of predefined coupling patterns reflecting the fiber orientation. The fitted coupling patterns were displayed as images and assigned to different muscles based on segmented MR images. They showed gross differences in fiber orientation between some muscles, including m. soleus and m. tibialis anterior, for all subjects. In addition, smaller but significant differences between subjects were detected, which could be due to localization differences or real interindividual differences. Since dipolar splitting affects metabolite intensities, it is important to take this effect into account when calculating metabolite concentrations from MR spectra in muscle tissue. Spatial maps of the MR signals of trimethyl‐ammonium groups and creatine/ phosphocreatine revealed significant differences in intensity between muscles. Magn Reson Med 49:424–432, 2003. © 2003 Wiley‐Liss, Inc.