中文摘要：

目的应用MR弹性成像（MRE）技术评估健康志愿者脑组织的剪切模量，并了解脑组织剪切模量与年龄间是否存在相关性。方法选取105名健康志愿者，其中男42名、女63名，行头部MRE检查。通过局部频率估算法（LFE）分别测量志愿者脑灰质与脑白质的剪切模量。采用独立样本t检验评估脑灰质与脑白质剪切模量间是否存在差异，以及脑实质剪切模量是否存在性别差异；应用Spearman相关分析评估剪切模量与年龄是否存在相关性，并将志愿者分为≤40岁组（76名）和〉40岁组（29名），分别进行脑实质剪切模量与年龄间的相关性分析。结果105名健康志愿者脑白质的剪切模量[（23．1±5．7）kPa]高于脑灰质[（11．3±2．6）kPa]，两者间差异具有统计学意义（t=19．34，P〈0．01）。男性志愿者脑白质与脑灰质的剪切模量分别为（23．4±5．8）、（1t．4±2．8）kPa，女性志愿者分别为（22．8±5．6）、（11．1±2．5）kPa。男、女志愿者脑组织间剪切模量值差异无统计学意义（t值分别为-0．534、-0．606，P值均〉0．05）。年龄相关性分析显示，灰质的剪切模量与年龄呈正相关（r=0．315，P〈0．01），白质的剪切模量与年龄无相关性（r=0．183，P〉0．05）；≤40岁组志愿者灰、白质剪切模量与年龄呈正相关（，值分别为0．251、0．235，P值均〈0．05），而〉40岁组志愿者脑灰、白质剪切模量均与年龄无相关性（r值分别为0．181、-0．001，P值均〉0．05）。结论健康志愿者脑白质的剪切模量明显高于脑灰质；脑实质剪切模量男女之间无差别；脑灰质剪切模量随年龄增加而增加。

英文摘要：

Objective To evaluate the healthy Chinese volunteers and to assess the shear stiffness of brain by MR elastography （MRE） in association between the cerebral shear stiffness and age. Methods Brain MRE studies were performed on 105 healthy volunteers. The shear stiffness of brain parencham was measured by local frequency estimation （ LFE ） algorithm. The differences of the shear stiffness between white matter（WM） and grey matter（GM） were analyzed by independent sample t test; the differences of brain parenchyma shear stiffness between male and female were estimated by independent sample t test. Spearman test was used to analyze the correlation between age and the shear stiffness of parenchyma; the volunteers were divided into two groups （age ≤40 and age 〉40） and the correlation between age and shear stiffness of parenchyma in each group were analyzed separately. Results The shear stiffness of whiter matter [ （23.1±5.7） kPa] was higher than that of grey matter[ （ 11.3 ±2. 6） kPa] ,and the difference was significant （t = 19.34, P 〈 0.01 ）. In male, the shear stiffness of WM and GM was （23.4 ± 5.8） kPa and （ 11.4 ± 2.8 ） kPa respectively ; while in female, it was （ 22. 8 ±5.6 ） kPa and （ 11.1 ± 2. 5 ） kPa respectively. No sex differences were found in the stiffness of white matter or gray matter （ t = - 0. 534, - 0. 606,P 〉 0. 05 ）. An age-dependent trend was observed in the stiffness of grey matter（ r = 0. 315, P 〈 0. 01 ）, while not in whiter matter （ r = 0. 183, P 〉 0. 05 ）. When the shear stiffness of subjects no more than 40 years old was analysed, the age-dependent trend of shear stiffness was found both in white matter and gray matter（ r = 0. 251,0. 235 ,P 〈 0. 05 ） ; While in subjects over 40 years old, the age-dependent trend of shear stiffness was not found in white matter or gray matter （ r = 0. 181, - 0. 001, P 〉 0.05 ）. Conclusions The shear stiffness of WM is significantly higher than that of GM. No obvious sex dif