What is the role of MR spectroscopy in the diagnosis of multiple sclerosis (MS)?

Updated: Mar 27, 2019
  • Author: James A Wilson, MD, MSc, FRCPC; Chief Editor: James G Smirniotopoulos, MD  more...
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Answer

Answer

Magnetic resonance (MR) spectroscopy uses the characteristic spectra of specific biochemical markers to quantitate organic compounds in vivo. N -acetylaspartate (NAA) is a relatively specific neuronal marker that is present in sufficient concentrations in the brain to be revealed on MR spectroscopic images. By comparing the spectral signal of NAA with that of creatinine (Cr), MR spectroscopy can be useful in assessing neuronal and axonal loss.

Arnold et al noted that the NAA-Cr ratio in the CNS was decreased in moderate to advanced MS. White matter that appeared normal on T1- and T2-weighted images also demonstrated the reduction. [41] In addition, a normal ratio was noted in the area of a recently active lesion associated with clinical deficits that subsequently resolved. The findings led the authors to propose that MR spectroscopic findings may be able to help identify irreversible axonal damage.

In a study involving 88 patients with MS, De Stefano et al found a strong correlation between disability scores and NAA-Cr ratios. [42] The ratio exhibited a stronger correlation in patients with MS patients who had milder disability scores. Because MR spectroscopy appears to be capable of depicting changes in white matter that are not detected with routine pulse sequences and because the findings are correlated with disability scores, the use of MR spectroscopy may prove valuable in monitoring patients after treatment and in formulating their prognosis.


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