脑组织正常老化的弥散张量成像研究

A diffusion tensor imaging study of usual aging in human brain

目的通过核磁共振弥散张量成像(diffusion tensor imaging,DTI)来反映由于正常老化引起的脑组织弥散及各项异性改变。方法通过对年轻组及其年老组脑组织的弥散张量成像,获得脑组织的平均弥散(average diffusion coefficient,ADC)图及部分各项异性(fractional anisotropy,FA)图,分别测量不同兴趣部位(region of interest,ROI)的ADC值及FA值,通过统计学分析来反映2组相应部位脑组织弥散及各项异性的差异,并探讨引起这种改变的原因。结果分别对于年轻组和年老组的对称部位而言,左右侧的ADC值及FA值没有差异(P>0.05)。除内囊膝部外,年老组各个兴趣区的ADC值均大于年轻组(P<0.05);而对于FA值而言,所有测量部位的FA值在年老组均比年轻组低(P<0.05)。结论DTI可以反映由于正常老化所引起的脑组织弥散、各向异性改变,从而反映脑组织微结构及完整性的改变。

Objective To investigate the usual brain by diffusion tensor imaging （DTI）. Methods aging-related changes in diffusivity and anisotropy of the Average diffusion coefficient （ADC） and fractional anisotropy （FA） maps of brain were gained by DTI. We measured ADC and FA values of interested structures for the changes in diffusivity and anisotropy, and attempted to discover the underlying microstructure changes. Results In young （20 -39 years of age） and old （more than 60 years of age） groups without brain disease-related aging, ADC and FA values of symmetric structures had no statistical significance （P 〉 0. 05 ）. ADC values in the old group were higher than those in the young group （P 〈 0.05 ）, except the values in bilateral genu of interual capsules. Meanwhile, FA values of the old group were lower in all ROIs than those in the young group （P 〈 0. 05）. Conclusion DTI reflects the changes in diffusivity and anisotropy of brain caused by usual aging, and the underlying changes of microstructure and integrity.