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Abstract #1476

Monitoring De- and Re- Myelination MR Spectroscopy Surrogate Markers in the Mouse Brain at 9.4 T

Zaaraoui W, Merle M, Raffard G, Deloire M, Gonen O, Franconi J, Petry K, Biran M, Inglese M, Dousset V
New York University, RMSB UMR 5536

Proton MR spectroscopy (1H-MRS) is frequently used to augment the sensitivity of MRI with metabolic specificity. The main surrogate markers monitored by 1H-MRS are the N-acetylaspartate (NAA) which is exclusive to neuronal cells, the mixture of free and phosphor-creatine (Cr) reflecting cell energetics, and the composite of free and phospho-choline (Cho) which reflects membrane turnover. Unfortunately, increases or declines in their levels are rarely definitive of the underlying process. For example, a decline in NAA may reflect neuronal dysfunction (which may be recoverable) or loss, which is permanent. Likewise, elevated Cho may indicate membrane destruction or recovery or even an admixture of the two processes. There has been precious little direct validation, i.e., direct quantitative pathological verification, of the underlying molecular processes steering the MR observed behavior of these surrogates. The goal of this study was to validate the nature of the MRS surrogate markers in a known model of de- a