脑白质小血管缺血性病变的MRS、DTI研究

目的应用磁共振波谱（MRS）与磁共振弥散张量成像（DTI）,分析脑白质小血管缺血性病变的微观改变。方法选取发生在半卵圆中心、放射冠区的脑白质小血管缺血性病变患者作为研究对象,其中急性腔隙性梗死组（腔梗组）病灶12例,缺血性脑白质疏松组（疏松组）病灶20例,并设置15例正常志愿者作为对照组,行半卵圆中心、放射冠区T1WI、T2WI、T2FLAIR、DWI、MRS、DTI扫描。测量N-乙酰天门冬氨酸（NAA）、胆碱（Cho）、肌酸（Cr）值,测量平均弥散系数（MD）值,各向异性分数（FA）值。比较各组间的差异。结果与对照组比较,腔梗组与疏松组NAA、FA值均显著降低（P〈0.01）,腔梗组与疏松组之间,NAA、FA值没有明显差异（P〉0.05）。结论在脑白质小血管缺血性病变中,NAA、FA值显著降低,共同反映了神经轴突髓鞘结构和功能的损伤、破坏;联合应用MRS、DTI分析评价脑白质小血管缺血性病变,将有助于全面认识其发病机制及病理改变。

Study of cerebral white matter in small vessel ischemic disease with MRS and DTI

Objective To observe the microscopic changes of cerebral white matter in small vessel ischemic diseases with magnetic resonance spctroscopy （MRS） and diffusion tensor imaging （DTI）. Methods Twelve patients with acute white matter lacunar infarction, and 20 patients with ischemic leukoaraiosis, which located in the centrum semiovale and corona radiate areas, and 15 healthy volunteers were recruited. T1WI, T2WI, T2FLAIR, DWI, MRS and DTI scans were performed for the patients and volunteers. Then the values of the average diffusivity （ MD）, fractional anisotropy （ FA）, and the level of N-acetyl aspartate （NAA）, choline （Cho）, and creatine （Cr） were measured and compared between three groups. Results There were significant reductions of NAA and FA values in the lacunar infarction group compared with the control group, and in the leukoaraiosis group compared with the control group （P〈0. 01 ）. There was no significant difference in NAA and FA values between the lacunar infarction group and the leukoaraiosis group （P〉0. 05）. Conclusions NAA and FA values significantly decrease in small vessel ischemic diseases, which reflects the microscopic structural and functional changes in axonal myelin sheathes of cerebral white matter. It will be helpful to understand the pathogenesis and pathological changes in small vessel ischemic diseases by using MRS and DTI.