Proton MR spectroscopy in multiple sclerosis: value in establishing diagnosis, monitoring progression, and evaluating therapy.

MR imaging is currently the technique of choice for evaluating brain lesions in patients with multiple sclerosis (MS). In addition to MR imaging, proton MR spectroscopy has shown potential in diagnosing MS and monitoring the progression of treatment. Spatially localized proton spectroscopy has been used to evaluate changes in choline, creatine, N-acetyl aspartate (NAA), lipids, and lactate in MS patients and in animal models of MS. The main spectroscopic findings are a decrease in the NAA:creatine ratio and an increase in the choline:creatine ratio in brain regions that include plaques defined by MR imaging. Proton MR spectroscopy along with MR imaging may be helpful in distinguishing those early lesions that might respond to therapy from late irreversible lesions. Preliminary evidence suggests that although the proton spectra acquired from patients with various brain diseases are similar (high choline, low NAA), there are differences in other resonances (lipids, lactate, glutamate, inositol) that could potentially help in diagnosing MS. Changes in proton metabolites potentially can be used to differentiate between the different stages of the MS lesion (hyperacute and edematous lesions, demyelinated lesions, and subacute to chronic plaques). It is hypothesized that successful treatment of demyelination and neuronal damage will be accompanied by changes in the proton spectrum (high choline:creatine ratio will lower to normal values and low NAA:creatine values will rise to normal values).