From the Department of Neurosurgery, Tokyo Medical and Dental University, Japan (S.H., Y.T, M.I., T.M., and T.N.).
Department of Radiology, Juntendo University, Tokyo, Japan (S.H., M.H., S.M., R.U., and S.A.).
Stroke. 2018 Oct;49(10):2504-2507. doi: 10.1161/STROKEAHA.118.022367.
Background and Purpose -Microstructural damage in the brain induced by chronic ischemia is suggested to play a pivotal role in the neurocognitive dysfunction of adults with Moyamoya disease (MMD). We investigated specific changes in the brain microstructure and their correlations with neurocognitive dysfunction in patients with MMD using a multishell diffusion magnetic resonance imaging technique called neurite orientation dispersion and density imaging. Methods- We evaluated 26 patients with MMD (16-63 years old, 20 females) and 20 age- and sex-matched normal volunteers using neurite orientation dispersion and density imaging and neuropsychological batteries. Neurite orientation dispersion and density imaging calculates 2 parameters: the intracellular volume fraction (Vic), which reflects the axon density in the white matter and dendrite density in the cortex, and the orientation dispersion index (OD), which reflects the network complexity. The microstructural damage and its correlation with neurocognitive performance were evaluated by performing a whole-brain analysis using SPM12 and correlation analysis with regional values. Results- Patients with MMD had significantly lower Vic in the white matter and a lower OD mainly in the cortex than those of the controls ( P<0.001, family-wise error corrected). Of all neuropsychological scores, Processing Speed Index (PS) exhibited the strongest correlation with Vic in the white matter ( P<0.001, family-wise error corrected). The Vic and OD values for regions with group differences, including both temporoparietal and frontal areas, correlated with neurocognitive performance (absolute r=0.37-0.64; P<0.01). Conclusions- Chronic ischemia in MMD may decrease the axon density in the white matter and dendrite density in the cortex (Vic) and simplify network complexity (OD), leading to neurocognitive dysfunction. Processing Speed Index may be the most sensitive index used to evaluate the ischemic burden, and the posterior part of the brain may play an important role in neurocognitive function. Clinical Trial Registration- URL: http://www.umin.ac.jp/ctr/ . Unique identifier: UMIN000023082.
背景与目的-慢性缺血引起的脑微观结构损伤被认为在烟雾病（MMD）成年患者的神经认知功能障碍中起关键作用。我们使用称为神经丝取向分散和密度成像（NODDI）的多壳扩散磁共振成像技术，研究了 MMD 患者脑微观结构的特定变化及其与神经认知功能障碍的相关性。
方法-我们使用 NODDI 和神经心理学量表评估了 26 例 MMD 患者（16-63 岁，20 名女性）和 20 名年龄和性别匹配的正常志愿者。NODDI 计算了 2 个参数：细胞内体积分数（Vic），反映白质中的轴突密度和皮质中的树突密度；以及取向分散指数（OD），反映网络复杂性。通过使用 SPM12 进行全脑分析和与区域值的相关性分析，评估微观结构损伤及其与神经认知表现的相关性。
结果-MMD 患者的白质 Vic 和皮质 OD 明显低于对照组（P<0.001，经家族错误校正）。在所有神经心理学评分中，处理速度指数（PS）与白质 Vic 相关性最强（P<0.001，经家族错误校正）。具有组间差异的区域（包括颞顶和额区）的 Vic 和 OD 值与神经认知表现相关（绝对 r=0.37-0.64；P<0.01）。
结论-MMD 中的慢性缺血可能导致白质中的轴突密度和皮质中的树突密度（Vic）降低，以及网络复杂性（OD）简化，导致神经认知功能障碍。处理速度指数可能是评估缺血负担最敏感的指标，而大脑后部可能在神经认知功能中发挥重要作用。
