左右利手成年人脑白质结构差异的磁共振成像及弥散张量成像研究

Structural magnetic resonance imaging and diffusion tensor imaging study on white matter in left- and right-handed adults

目的探讨左右利手成年人脑白质结构差异及差异脑区各指标之间的相关性。方法对23名左利手和32名右利手成年人进行结构磁共振成像(structural magnetic resonance imaging,sMRI)和弥散张量成像(diffusion tensor imaging,DTI)扫描,采用基于体素的形态测量学方法(voxel-based morphometry,VBM)、基于体素分析(voxel-based analysis,VBA)和基于感兴趣区(region of interest,ROI)的确定性纤维束追踪方法,比较脑白质体积、各向异性分数(fractional anisotropy,FA)和平均弥散系数(meandiffusivity,MD)的组间差异,并分析有差异脑区内各指标之间的关系。结果(1)与右利手组相比,左利手组双侧胼胝体压部(左侧:x=-15,y=-57,z=13.5,t=-5.160;右侧:x=18,y=-42,z=12,t=-3.654)白质体积减小(P<0.001);左侧中央后回下部(x=-24,y=-46,z=54)、左侧岛叶上缘(x=-36,y=-12,z=20)的FA值增高(P<0.001)及通过其脑区纤维束的平均FA值、平均长度和纤维条数增加(P<0.05);右侧海马(x=24,y=-34,z=-2)的MD值降低(P<0.001)及通过该脑区纤维束的平均MD值降低、平均长度增加(P<0.05)。(2)左右利手组脑白质体积差异脑区右侧胼胝体压部白质体积与FA值(左利手组r=0.716,右利手组r=0.471)均呈正相关(P<0.05);左右利手组FA差异脑区左侧中央后回下部(左利手组r=-0.769,右利手组r=-0.841)、左侧岛叶上缘(左利手组r=-0.775,右利手组r=-0.744);左右利手组MD差异脑区右侧海马(左利手组r=-0.842,右利手组r=-0.742)FA与MD值均呈负相关(P<0.05)。结论左利手与右利手人群的脑白质存在宏观体积和微观结构差异,差异分布于多个脑区及纤维束,且不同差异指标间存在一定的关联性。

Objective To explore the differences of macrostructural and microstructural and their correlations in brain white matter(WM)between left- and right-handed adults.Methods Structural magnetic resonance imaging(sMRI)and diffusion tensor imaging(DTI)were performed on twenty-three left-handed(LH)and thirty-two right-handed(RH)healthy subjects.The WM volume,fractional anisotropy(FA)and mean diffusivity(MD)were mearsured and compared between the two groups by using the voxel-based morphometry(VBM)and voxel-based analysis(VBA)methods.Results(1)LH adults showed lower WM volume than RH adults in bilateral splenium of corpus callosum(SC)(Left: x=-15,y=-57,z=13.5,t=-5.160;Right: x=18,y=-42,z=12,t=-3.654;P<0.001).Compared with the RH adults,the FA values in WM of the left postcentral gyrus(PoCG)(x=-24,y=-46,z=54)and the above left insula(INS)(x=-36,y=-12,z=20)increased(P<0.001),as well as the average FA values,the average length and number of streamlines in WM tracts increased(P<0.05)in LH adults.Compared with the RH adults,the MD values in the right HIP(x=24,y=-34,z=-2)decreased(P<0.001),as well as the average MD values decreased,and the average length in WM tracts increased(P<0.05)in LH adults.(2)There was positive correlation between FA and the volume of right splenium of corpus callosum in LH and RH adults(LH: r=0.716,RH: r=0.471,P<0.05).There was negative correlation between FA and MD in the left PoCG(LH : r=-0.769,RH: r=-0.841),left INS(LH: r=-0.775,RH : r=-0.744)and right HIP(LH: r=-0.842,RH: r=-0.742)in LH and RH adults(all P<0.05).Conclusion There are differences in both macrostructure and microstructure of white matter in several brain regions and WM tracts between left-handed and right-handed people,and correlations between these measures were also observed.