Department of Radiology, Washington University, St. Louis, MO 63110, USA.
NMR Biomed. 2011 Feb;24(2):163-9. doi: 10.1002/nbm.1567. Epub 2010 Dec 8.
Degeneration of motor neurons and their associated axons is a hallmark of amyotrophic lateral sclerosis, but reliable noninvasive lesion detection is lacking. In vivo diffusion tensor imaging was performed to evaluate neurodegeneration in the brainstem and cervical spinal cord of wild-type and G93A-SOD1 transgenic mice, an animal model of amyotrophic lateral sclerosis. A statistically significant reduction in the apparent diffusion coefficient was observed in the motor nuclei VII and XII of G93A-SOD1 transgenic mice relative to wild-type mice. No significant difference in diffusion anisotropy was observed in dorsal white or gray matter in cervical and lumbar segments of the spinal cord. In contrast, statistically significant decreases in axial diffusivity (diffusivity parallel to the axis of the spinal cord) and apparent diffusion coefficient were found in the ventrolateral white matter of G93A-SOD1 mice in both the cervical and lumbar spinal cord. The reduction in axial diffusivity, suggestive of axonal injury, in the white matter of the spinal cord of G93A-SOD1 mice was verified by immunostaining with nonphosphorylated neurofilament. The present study demonstrates that in vivo diffusion tensor imaging-derived axial diffusivity may be used to accurately evaluate axonal degeneration in an animal model of amyotrophic lateral sclerosis.
运动神经元及其相关轴突的变性是肌萎缩性侧索硬化症的标志，但可靠的非侵入性病变检测方法仍缺乏。本研究采用活体扩散张量成像技术，评估野生型和 G93A-SOD1 转基因（肌萎缩性侧索硬化症动物模型）小鼠脑干和颈脊髓的神经退行性变。与野生型小鼠相比，G93A-SOD1 转基因小鼠的运动核 VII 和 XII 的表观扩散系数明显降低。在颈段和腰段脊髓的背侧白质和灰质中，扩散各向异性无显著差异。相反，在 G93A-SOD1 转基因小鼠的颈、腰段脊髓腹外侧白质中，轴向扩散系数（与脊髓轴平行的扩散）和表观扩散系数显著降低。免疫组化染色显示非磷酸化神经丝提示 G93A-SOD1 小鼠脊髓白质中的轴突损伤，证实了脊髓 G93A-SOD1 小鼠白质中轴突弥散度降低与轴突损伤有关。本研究表明，活体扩散张量成像衍生的轴向弥散度可用于准确评估肌萎缩性侧索硬化症动物模型中的轴突变性。
