14800-DvRappard

115 Quantitative MR spectroscopic imaging in metachromatic leukodystrophy 7 Figure 4 : MLD-GMF score at latest follow up as function of WM NAA concentration at baseline. Spearman’s rank correlation = -0.78 (p<0.01). Green, orange and red symbols correspond to patients with good, moderate and poor outcome, respectively. Non-eligible patients are indicated with triangles, and eligible patients with circles. Longitudinal evaluation Baseline and longitudinal WM concentrations of NAA, the concentration ratio Cho/ NAA, MRI scores, and lesion volumes for all patients are shown in Figure 5. In general, absolute metabolite concentrations showed longitudinal fluctuations, for NAA as well as for Cr, Glx and all other metabolites (not shown), comparable to those observed in healthy control subjects. 17 Concentration ratios have higher reproducibility, and since we previously showed that Cho/NAA is sensitive for improvement after HCT, 12 we chose to display this ratio in figure 5B. Although this ratio slightly increased in some patients in the first examination after HCT, this was reversible in all patients with good outcome. In adult patients with moderate outcome, we also observed ongoing decrease of Cho/ NAA, but this ratio did not decrease in two juvenile patients with moderate outcome. Remarkably, in several patients with good or moderate outcome we observed a decrease of Cho/NAA, which did not coincide with a decrease in MRI score or lesion volume (Figure 5C,D). In the treated non-eligible patient who died 11 months post-HCT, metabolites and imaging markers all clearly deteriorated as both Cho/NAA and the MRI score and lesion volume strongly increased after HCT.