Tsuganesawa T, Igarashi H, Kitamura S, Terashi A
Second Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
Nihon Ika Daigaku Zasshi. 1998 Apr;65(2):167-72. doi: 10.1272/jnms1923.65.167.
To investigate changes in both water diffusion coefficients and diffusion anisotropy in white matter of non-demented patients with leuko-araiosis using diffusion-weighted MRI.
Diffusion mapping was performed on 8 non-demented patients with leuko-araiosis, 6 patients with chronic cerebral infarction and 6 healthy volunteers, using a spin-echo sequence with motion probing gradient applied sequentially at two gradient strength settings in three orthogonal directions. The apparent diffusion coefficients (ADC) were calculated from 4 regions of interest located within the frontal and parietal subcortical white matter. The index of diffusion anisotropy (IDA) was calculated from the ADC in three orthogonal directions. (IDA = ADCmax-min/ADCmean x 100).
Significantly larger ADC were found within the frontal and parietal subcortical white matter in the non-demented patients with leuko-araiosis (mean = 1.51 +/- 0.36 x 10(-3) mm2/s) and the were also significantly larger in patients with cerebral infarction (mean = 2.12 +/- 0.46 x 10(-3) mm2/s) than in the control group (mean = 1.01 +/- 0.33 x 10(-3) mm2/s). But no significant differences were found in the IDA between the non-demented patients with leuko-araiosis (mean = 43.1 +/- 29.2) and the control group (mean = 46.5 +/- 32.5).
An increase in extracellular space caused by the loss of axonal fibers and myelin is probably the cause of the higher ADC in periventricular hyperintensity lesions. However, the remaining nerve fibers maintain the anisotropy in the lesions in non-demented patients with leuko-araiosis.
使用扩散加权磁共振成像（MRI）研究非痴呆性脑白质疏松症患者白质中水扩散系数和扩散各向异性的变化。
对8例非痴呆性脑白质疏松症患者、6例慢性脑梗死患者和6名健康志愿者进行扩散图谱分析，采用自旋回波序列，在三个正交方向上依次以两种梯度强度设置应用运动探测梯度。从额叶和顶叶皮质下白质内的4个感兴趣区域计算表观扩散系数（ADC）。从三个正交方向的ADC计算扩散各向异性指数（IDA）。（IDA = ADC最大值 - 最小值/ADC平均值×100）。
非痴呆性脑白质疏松症患者额叶和顶叶皮质下白质中的ADC显著更大（平均值 = 1.51 ± 0.36×10⁻³ mm²/s），脑梗死患者的ADC也显著大于对照组（平均值 = 2.12 ± 0.46×10⁻³ mm²/s）（对照组平均值 = 1.01 ± 0.33×10⁻³ mm²/s）。但非痴呆性脑白质疏松症患者与对照组之间的IDA无显著差异（非痴呆性脑白质疏松症患者平均值 = 43.1 ± 29.2，对照组平均值 = 46.5 ± 32.5）。
轴突纤维和髓鞘丢失导致细胞外间隙增加可能是脑室周围高信号病变中ADC升高的原因。然而，在非痴呆性脑白质疏松症患者中，剩余的神经纤维维持了病变中的各向异性。
