Correction of HEAL Registry Data Report.

indicative of a rise in membrane turnover upon increased Cho expression. Its expression level is usually increased in subacute and acute MS lesions. An increase in the amount of Cho-containing compounds has been detected in prelesional NAWM, at least 12 months before lesions became visible by conventional MR imaging as a result of early myelin membrane pathology. It is noteworthy that Cho seems to be relatively stable outside of MS lesions. We think that this metabolite should be considered a reference for evaluating NAA values, possibly in combination with Cr determination, and that Cho could become a useful alternative biomarker to Cr in nonlesional WM. In a previous report, our group also found a significant decrease in NAA in NAWM without a concomitant decrease of the NAA/Cr ratio. Conflicting results have been published regarding the Cr concentration in MS lesions. In our opinion, the determination of more than one ratio by spectroscopy, including NAA/Cr and NAA/Cho, could be more beneficial than evaluating a single ratio, would allow for a better understanding of the pathophysiologic mechanisms of MS, and, if there is agreement between the results, would lend consistency to the spectroscopic data.