Dysmyelination revealed through MRI as increased radial (but unchanged axial) diffusion of water
Dysmyelination revealed through MRI as increased radial (but unchanged axial) diffusion of water
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DOI：
10.1006/nimg.2002.1267
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发表时间：
2002-11-01
期刊：
影响因子：
5.7
通讯作者：
Cross, AH
中科院分区：
文献类型：
--
作者：
Song, SK;Sun, SW;Cross, AH
髓磷脂丢失和轴突损伤均可见于白质损伤。每一种都可能对患者的长期残疾产生重大影响。目前，还没有一种非侵入性的生物标志物能够区分髓鞘损伤和轴索损伤。我们在此描述了使用磁共振扩散张量成像（DTI）来量化髓鞘异常对体内震颤小鼠大脑水定向扩散率的影响。测量了在DTI图上可以确定识别的8个轴突纤维束的主扩散特征值。与年龄匹配的对照组相比，颤栗小鼠轴突纤维束垂直方向的水扩散率λ（垂直于）明显更高，这反映了髓磷脂的缺乏和白质中跨纤维扩散的自由增加。平行于轴突纤维束的水扩散系数λ（平行于）没有差异，这与完整轴突的存在是一致的。很明显，髓鞘发育异常本身并不影响lambda（平行于）。电镜证实髓鞘形成不完全的情况下存在完整的轴突。虽然还需要进一步的验证，但我们的发现表明，lambda（垂直于）和lambda（平行于）的变化可能潜在地用于区分髓磷脂损失和轴索损伤。(C) 2002 Elsevier Science （USA）。
Myelin loss and axonal damage are both observed in white matter injuries. Each may have significant impact on the long-term disability of patients. Currently, there does not exist a noninvasive biological marker that enables differentiation between myelin and axonal injury. We describe herein the use of magnetic resonance diffusion tensor imaging (DTI) to quantify the effect of dysmyelination on water directional diffusivities in brains of shiverer mice in vivo. The principal diffusion eigenvalues of eight axonal fiber tracts that can be identified with certainty on DTI maps were measured. The water diffusivity perpendicular to axonal fiber tracts, lambda(perpendicular to), was significantly higher in shiverer mice compared with age-matched controls, reflecting the lack of myelin and the increased freedom of cross-fiber diffusion in white matter. The water diffusivity parallel to axonal fiber tracts, lambda(parallel to), was not different, which is consistent with the presence of intact axons. It is clear that dysmyelination alone does not impact lambda(parallel to). The presence of intact axons in the setting of incomplete myelination was confirmed by electron microscopy. Although further validation is still needed, our finding suggests that changes in lambda(perpendicular to) and lambda(parallel to) may potentially be used to differentiate myelin loss versus axonal injury. (C) 2002 Elsevier Science (USA).