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

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. Key words: Handedness; Structural magnetic resonance imaging (sMRI); Diffusion tensor imaging (DTI); White matter; Fiber tracking; Correlation