Nevo U, Hauben E, Yoles E, Agranov E, Akselrod S, Schwartz M, Neeman M
Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Magn Reson Med. 2001 Jan;45(1):1-9. doi: 10.1002/1522-2594(200101)45:1<1::aid-mrm1001>3.0.co;2-i.
Spinal cord injury and its devastating consequences are the subject of intensive research aimed at reversing or at least minimizing functional loss. Research efforts focus on either attenuating the post-injury spread of damage (secondary degeneration) or inducing some regeneration. In most of these studies, as well as in clinical situations, evaluation of the state of the injured spinal cord poses a serious difficulty. To address this problem, we carried out a diffusion-weighted MRI experiment and developed an objective routine for quantifying anisotropy in injured rat spinal cords. Rats were subjected to a contusive injury of the spinal cord caused by a controlled weight drop. Untreated control rats were compared with rats treated with T cells specific to the central nervous system self-antigen myelin basic protein, a form of therapy recently shown to be neuroprotective. After the rats were killed their excised spinal cords were fixed in formalin and imaged by multislice spin echo MRI, using two orthogonal diffusion gradients. Apparent diffusion coefficient (ADC) values and anisotropy ratio (AI) maps were extracted on a pixel-by-pixel basis. The calculated sum of AI values (SAI) for each slice was defined as a parameter representing the total amount of anisotropy. The mean-AI and SAI values increased gradually with the distance from the site of the lesion. At the site itself, the mean-AI and SAI values were significantly higher in the spinal cords of the treated animals than in the controls (P = 0.047, P = 0.028, respectively). These values were consistent with the score of functional locomotion. The difference was also manifested in the AI maps, which revealed well-organized neural structure in the treated rats but not in the controls. The SAI values, AI histograms, and AI maps proved to be useful parameters for quantifying injury and recovery in an injured spinal cord. These results encourage the development of diffusion anisotropy MRI as a helpful approach for quantifying the extent of secondary degeneration and measuring recovery after spinal cord injury. Magn Reson Med 45:1-9, 2001.
脊髓损伤及其严重后果是旨在逆转或至少最小化功能丧失的深入研究的主题。研究工作集中在减轻损伤后损伤的扩散（继发性变性）或诱导某种再生。在大多数这些研究以及临床情况下，评估受损脊髓的状态都存在严重困难。为了解决这个问题，我们进行了一项扩散加权磁共振成像（MRI）实验，并开发了一种客观的程序来量化受损大鼠脊髓中的各向异性。对大鼠进行可控重量下降导致的脊髓挫伤。将未治疗的对照大鼠与用针对中枢神经系统自身抗原髓磷脂碱性蛋白的T细胞治疗的大鼠进行比较，最近已证明这种治疗形式具有神经保护作用。大鼠处死后，将其切除的脊髓固定在福尔马林中，并使用两个正交扩散梯度通过多层自旋回波MRI成像。逐像素提取表观扩散系数（ADC）值和各向异性比率（AI）图。将每个切片计算的AI值总和（SAI）定义为代表各向异性总量的参数。平均AI和SAI值随着与损伤部位距离的增加而逐渐增加。在损伤部位本身，治疗组动物脊髓中的平均AI和SAI值显著高于对照组（分别为P = 0.047，P = 0.028）。这些值与功能运动评分一致。这种差异在AI图中也很明显，AI图显示治疗组大鼠的神经结构组织良好，而对照组则不然。SAI值、AI直方图和AI图被证明是量化受损脊髓损伤和恢复情况的有用参数。这些结果鼓励将扩散各向异性MRI开发为一种有助于量化继发性变性程度和测量脊髓损伤后恢复情况的方法。《磁共振医学》45:1 - 9, 2001年。
