正常成人脑投射纤维年龄相关性变化的扩散张量成像研究

DTI Research of Normal Adult Brain Projection Fibers Age-related Change

目的应用磁共振扩散张量成像技术（DTI）定量研究正常年轻人和中老年人脑投射纤维平均扩散系数（DCavg）和部分各向异性（FA）的差异及与年龄的关系。方法收集15例正常中老年志愿者作为中老年组,年龄45~75岁;15例年轻志愿者作为青年组,年龄24~29岁,分组原则为青年组（≤44岁）,中老年组（〉45岁）。所有志愿者均接受常规MR及DTI扫描,重建DCavg和FA图,测量两组志愿者不同层内脑投射纤维的4个感兴趣区（ROI）的DCavg值和FA值,比较两种参数值在两组间的差异,并分析其与年龄的相关性,P〈0.05认为差异有统计学意义。结果 （1）中老年组右侧大脑脚、右侧内囊后肢的DCavg值高于青年组（P=0.024、P=0.048）;（2）青年组两侧大脑脚、左侧内囊前肢及左侧内囊后肢的FA值高于中老年组（P=0.012、0.024、0.015、0.012）;（3）大脑脚的DCavg值与年龄呈正相关（r=0.44,P=0.01）,大脑脚、内囊前肢的FA值与年龄呈负相关（r=-0.60,P=0;r=-0.56,P=0）。结论 （1）正常青年人和中老年人脑投射纤维的DCavg值和FA值存在差异,中老年人DCavg值高于青年人,青年人FA值高于中老年人;（2）DCavg值和FA值与年龄具有相关性并且存在一定的规律。随着年龄段增长不同层面脑投射纤维的DCavg值与年龄具有正相关性;FA值与年龄具有负相关性。

Objective To investigate the age-related change of brain projection fibers average diffusion coefficient（DCavg）and fractional anisotropy（FA）between young adult and elderly adult through diffusion tensor imaging（DTI）.Method 15 elderly adults volunteers were collected as elderly group（mean age 59.07±10.00）;15 normal young adults volunteers as young group（mean age 26.93±1.62）,the grouping rules is young group（≤44 years old）,elderly group（45years old）.The two groups received normal head MR scan and DTI scan by 3.0T MRI.We rebuilt the DCavg and FA map and measured the corresponding four regions of interest（ROI）and compare the difference between the two group.At last,we analyzed the dependency between DCavg and FA with age,p value0.05 was considered statistically significant.Results（1）DCavg value of right cerebral peduncle and right posterior limb of internal capsule in elderly group were higher than that of young group（P=0.024、0.048）;（2）FA value of both sides of cerebral peduncle,left anterior limb of internal capsule and left posterior limb of internal capsule were higher than that of elderly group（P=0.012、0.024、0.015、0.012）;（3）DCavg value of cerebral peduncle had positive correlation with age（r=0.44,P=0.01）,FA value of cerebral peduncle and anterior limb of internal capsule had inverse correlation with age（r=-0.60,P=0;r=-0.56,P=0）.Conclusion（1）There is difference of normal adult brain projection fiber DCavg value and FA value between young adult and elder adult,DCavg value of elderly adult is higher than that of young adult.FA value of young adult is higher than that of elderly;（2）There are correlation and certain regularity of brain projection fiber between DCavg value and FA value with age,DCavg value has positive correlation with age.FA value has inverse correlation with age.