Pathologically defined abnormalities in the cortical gray matter (GM) are w
ell described in multiple sclerosis (MS) but are infrequently seen by conve
ntional magnetic resonance imaging (MRI). We systematically evaluated 52 re
lapsing-remitting MS patients and 20 normal volunteers with high resolution
MRI and short echo proton magnetic resonance spectroscopic imaging (MRSI).
Individual tissue contributions to the spectroscopic voxels were estimated
based on MRI that incorporated both CSF suppression and magnetization tran
sfer, or double inversion images in which both CSF and GM were suppressed.
Strong resonances in the 0.8 to 1.5 p.p.m. spectral region were observed in
13 MS patients. Image segmentation based on the MRI characteristics of tis
sues contributing to the spectroscopic voxels showed that these additional
peaks originated mainly from GM. The presence of these additional peaks sug
gests that the normal appearance GM on MRI, is biochemically abnormal in a
substantial proportion of relapsing-remitting MS patients.