老年人脑白质病变相关性跌倒患者的脑弥散张量成像研究

摘要

目的：定量分析老年人脑白质病变(white matter lesions, WMLs)相关性跌倒患者的脑弥散张量成像(diffusion tensor imaging, DTI)及临床改变，初步探索老年人跌倒风险的影像学预测指标。材料与方法选择2015年6月至2016年1月期间首都医科大学附属北京天坛医院60岁以上的WMLs患者，根据Tinetti平衡和步态量表划分为跌倒风险组15人(Tinetti＜25分)及对照组29人(Tinetti≥25分)。运用基于纤维束追踪空间统计分析(tract based spatial statistics, TBSS)识别跌倒风险组患者异常的脑白质纤维束，并与简易精神状态检查量表(mini mental state exam, MMSE)、蒙特利尔认知评估(montreal cognitive assessment, MoCA)量表、Tinetti平衡和步态量表(tinetti balance and gait analysis)、计时起立-步行测验(timed up and go test, TUGT)分别进行相关性分析。结果跌倒风险组的MMSE(t=2.806， P=0.008)及MoCA (t=2.890，P=0.006)量表评分低于对照组。跌倒风险组的全脑平均各向异性分数(fractional anisotropy, FA)值低于对照组(t=2.862，P=0.007)；跌倒风险组全脑平均FA值与MMSE(r=0.533，P=0.041)及MoCA(r=0.642， P=0.010)量表呈正相关。跌倒风险组FA值减低的脑白质纤维束为右侧钩束、胼胝体膝部、体部及压部、双侧放射冠前部、右侧放射冠上部、右侧上纵束、左侧扣带回；其中跌倒风险组的胼胝体膝部、右侧放射冠前部、胼胝体体部、胼胝体压部、右侧上纵束、左侧扣带回的平均FA值均与MoCA呈正相关(P值均＜0.05)；右侧钩束的平均FA值(r=0.562，P=0.029)与Tinetti平衡量表呈正相关；右侧钩束(r=0.572，P=0.026)、胼胝体体部(r=0.538，P=0.038)、胼胝体压部(r=0.580，P=0.023)、左侧扣带回(r=0.520，P=0.047)的平均FA值与Tinetti步态量表呈正相关；胼胝体体部(r=-0.582，P=0.023)及左侧扣带回(r=-0.538，P=0.039)的平均FA值与TUGT呈负相关。结论跌倒风险组的全脑平均FA值及9条脑白质纤维束平均FA值低于对照组，并与认知、步态、平衡功能存在一定的相关性。DTI定量分析可用于识别老年人WMLs相关性跌倒患者的颅脑结构特点，为具有跌倒风险的WMLs患者的识别、判断病情及预后评价提供了重要的影像学依据。%Objective: To analyze the diffusion tensor imaging (DTI) and clinical characteristic of the aged who had white matter lesions with fall risks, quantify the fall risk index and provide a basis for fall precautions. Materials and Methods: People aged more than 60 years old with brain white matter lesions from Beijing Tiantan Hospital, Capital Medical University, were included in study, according to the Tinetti Balance and Gait Analysis, 15 patients were divided into experimental group (Tinetti<25) and 29 contrast group (Tinetti≥25). The significantly different white matter fiber tracts were identified by Tract Based Spatial Statistics (TBSS) and were also made correlation analysis with MoCA, MMSE, Tinetti Gait Analysis, Tinetti Balance Analysis and TUGT. Results: There was statistic significance in the score of MMSE (t=2.806, P=0.008) and MoCA (t=2.890, P=0.006) between two groups with white matter lesions. In subjects with risk of falls, the mean FA of whole brain was lower than that of contrast group (t=2.862, P=0.007), and was positively correlated with MMSE (r=0.533, P=0.041) and MoCA (r=0.642, P=0.010). Significantly abnormal FA clusters (representing loss of WM integrity) of patients with risk of falls were seen in the right fasciculus uncinatus, genu, body and splenium of corpus callosum, both anterior corona radiate, right superior corona radiate, right superior longitudinal fasciculus and left cingulate gyrus. The mean FA of corpus callosum-genu, right superior corona radiate, body of corpus callosum, splenium of corpus callosum, right superior longitudinal fasciculus and left cingulate gyrus were positively correlated with MoCA scores in those with risk of falls(P<0.05). The mean FA of right fasciculus uncinatus (r=0.562, P=0.029) was positively correlated with Tinetti Balance Analysis. The mean FA of right fasciculus uncinatus (r=0.572, P=0.026), body of corpus callosum (r=0.538, P=0.038), splenium of corpus callosum (r=0.580, P=0.023) and left cingulate gyrus (r=0.520, P=0.047) were positively correlated with Tinetti Gait Analysis. The mean FA of body of corpus callosum (r=–0.582, P=0.023) and left cingulate gyrus (r=–0.538, P=0.039) were negatively correlated with TUGT. Conclusion: In subjects with risk of falls, the mean FA of whole brain and some white matter fiber tracts decreased, these differences were correlated with cognition, balance and gait. Therefore, DTI can identify the structural changes in brain of those with risk of falls and quantify the fall risk index.