Premium
Absolute metabolite concentrations calibrated using the total water signal in brain 1 H MRS
Author(s) -
Brief E. E.,
Moll R.,
Li D. K. B.,
MacKay A. L.
Publication year - 2009
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1349
Subject(s) - white matter , chemistry , metabolite , nuclear magnetic resonance , t2 relaxation , voxel , magnetic resonance imaging , analytical chemistry (journal) , physics , chromatography , medicine , biochemistry , radiology
Magnetic resonance spectroscopy (MRS) has been coupled with a multi‐echo imaging sequence to determine the relaxation corrected signal areas of the metabolites and the tissue water. Stimulated echo acquisition mode (STEAM) spectra (TE/TM/TR 30/13.7/5000 ms) acquired from gray and white matter voxels in 43 healthy volunteers were fit using LCModel. Corresponding water signals, measured using a multi‐echo T 2 imaging sequence, were fit with a Non‐Negative Least Squares algorithm. Using this approach the water area could be T 1 and T 2 corrected for all three water compartments: cerebrospinal fluid (CSF), intra‐ and extra‐cellular water, and myelin water. The image‐based water measurement is an improvement over spectroscopy methods because it can be more sensitive to water changes in diseased tissue. Metabolite areas were also corrected for relaxation losses. In occipital gray matter, the concentrations of Cho, Cr, and N ‐acetyl aspartate (NAA) were 1.27 (0.06), 8.9 (0.3), and 9.3 (0.3) mmol/L tissue, respectively and in parietal white matter they were 1.90 (0.05), 7.9 (0.2), and 9.8 (0.2) mmol/L tissue. The Cho and Cr concentrations were different in occipital gray compared to parietal white matter ( p < 0.0001 and <0.005, respectively). Copyright © 2008 John Wiley & Sons, Ltd.