[Magnetic resonance spectroscopy in multiple sclerosis]

Magnetic resonance spectroscopy allows in vivo neurochemical exploration of multiple sclerosis (MS) lesions and normal appearing white matter on MRI. It gives insights into pathophysiology: inflammation (increase of choline), recent demyelination (increase in lipids and choline), axonal dysfunction (decrease of NAA), gliosis (increase of myoinositol). The spectroscopic profile of lesions is not specific to MS. Therefore MRI remains the first investigation to perform when MS is suspected. However, spectroscopy is a sensitive, reproducible, non invasive tool which may provide an index of activity. In the future, spectroscopy may contribute in homogenizing patient selection for clinical trials and might be used, in association with MRI, to evaluate therapeutic efficiency. Spectroscopy might also influence therapeutic choices by identifying the prevailing lesional mechanism: inflammation, demyelination, axonal destruction, or gliosis.