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Abstract:
Anatomical MRI findings has limited value in predicting patient clinical status or the future course of the disease. Magnetic resonance spectroscopy (MRS) provides the means of accessing biochemical information from the neural tissue thus holding potential for better characterization of the disease and clinical decision-making. In this study, we examined metabolic alterations in the normal appearing white matter (NAWM) of both the brain (periventricular NAWM) and the cervical spinal cord (SC) at C3/C4 in different subgroups of MS. We measured spectra in 15 healthy controls (HC), 28 relapsing-remitting MS (RRMS) and 5 secondary progressive MS (SPMS) patients. The RRMS group is subdivided into three groups based on whether the expanded disability status scale (EDSS) has decreased (RRMSd), increased (RRMSi) or been stable (RRMSs) within the last 12 months prior to the MRS examination.
Concentration differences between HC and the patient groups were observed in SC and B for tNAA/tCho (SC/B:p=[0.003,0.011]) and tCho/Cr (SC/B:p=[0.01,0.006]). Additionally, in brain only, differences were found for tNAA/Cr (p=0.027), mI/Cr (p=0.08), Glu/Cr (p=0.016) and tNAA/mI (p=0.05) ratios. Statistical significant differences (false discovery rate corrected) occur between HC and RRMSi in tNAA/tCho (SC/B: p=[0.003,0.017]) and tCho/Cr (SC/B: p=[0.019,0.007]. HC and RRMSs have a significantly different tNAA/tCho (SC: p=0.003]) and tCho/Cr (SC: p=0.019) ratio. RRMSi and SPMS differ in the brain Glu/Cr ratio (p=0.028) and RRMSi and RRMSs have different brain tCho/Cr ratio (p=0.007). tNAA/tCho of the SC significantly correlates with tNAA/tCho of the brain (p<0.001). Changed concentration values detected by MRS may be an indicator of altered metabolism in NAWM of MS patients reflecting inflammation and neurodegeneration or an aggressive course of RRMS. We observed changes in metabolite ratios such as tCho/Cr or tNAA/tCho in both brain and SC. Metabolites including tNAA, Glu, tCho and mI seem to have discriminative power with regard to distinguishing MS subgroups. tNAA/tCho might be a marker of global metabolic abnormalities in NAWM of MS patients. The sensitivity of brain and SC MRS to distinguish clinical subgroups of RRMS with a difference in previous EDSS scores evolvement holds the potential for the use of MRS in therapy monitoring.
