Axonal injury in the cerebral normal-appearing white matter of patients with multiple sclerosis is related to concurrent demyelination in lesions but not to concurrent demyelination in normal-appearin

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• 作者：Sridar Narayanan ; Simon J. Francis ; John G. Sled ; A.C. Santos ; Samson Antel ; Ives Levesque ; Steven Brass ; Yves Lapierre ; Dominique Sappey-Marinier ; G. Bruce Pike and Douglas L. Arnold
• 刊名：NeuroImage
• 出版年：2006
• 出版时间：15 January 2006
• 年：2006
• 卷：29
• 期：2
• 页码：637-642
• 全文大小：319 K

文摘

We assessed axonal injury and demyelination in the cerebral normal-appearing white matter (NAWM) of MS patients in a pilot study using proton magnetic resonance spectroscopic imaging and quantitative magnetization transfer (MT) imaging. Resonance intensities of N-acetylaspartate (NAA) relative to creatine (Cr) were measured in a large central brain volume. NAA/Cr in NAWM was estimated by regression of the NAA/Cr in each voxel against white matter fraction and extrapolation to a white matter fraction of 1. The fractional size of the semi-solid pool (F) was obtained from the binary spin bath model of MT by computing the model parameters from multiple MT-weighted and relaxometry acquisitions. F in NAWM was significantly smaller in the patients [0.109 (0.009)] relative to controls [0.123 (0.007), P = 0.011], but did not differ between RR [0.1085] and SP [0.1087] patients [P > 0.99]. NAA/Cr and F in the NAWM were not correlated (r = 0.16, P > 0.7), mainly due to a lack of variation in F among patients. This may indicate a floor to the extent of myelin pathology that can occur in NAWM before a lesion appears, or that axonal damage is not strictly related to demyelination. The correlation between NAWM NAA/Cr and T2w lesion volume was not significant (P > 0.1). However, dividing the lesion volumes by the mean F in T2w lesions resulted in a quantity that correlated well with NAWM NAA/Cr (r = −0.78, P = 0.038), possibly reflecting the association of Wallerian degeneration in the NAWM with axonal transection associated with demyelination within lesions.