Diffusion Tensor Imaging Assessment Of Brain White Matter Maturation During The First Year Of Life

Objective: The purpose of this study was to use diffusion tensor imaging to observe and investigate the feature of anisotropy of cerebral white matter throughtout the first year of life in healthy infants.And then comprehend development status of cerebral white matter in different anatomic site. To Comprehend law of development of cerebral WM through the period.Materials and methods: We have picked out fourty-one infants(23boys 18girls) ranging in age from 1day to 51.5 weeks (mean age,21.03 weeks)from them who underwent conventional MRI,diffusion imaging in the first affiliated hospital of Hebei medical university from between 2008 and december 2009. They were divided intio four group. All subjects have undergone conventional MRI and diffusion tensor imaging with gradient encoding in 15 directions, (b = 1,000 s/mm2 )on a GE Signa Excite 1.5~T MRI system.ALL DTI data were processed by Functool software of GE Signa Exite 1.5T system.Fractional anisotropy (FA) were measured in five deep WM structures (posterior limb of internal capsule,anterior limb of internal capsule, genu, and splenium of corpus callosum) and four peripheral WM regions (associational WM underlying prefrontal and occipital lobe cortex, White matter of temporal lobe, centrum ovale)Mean FA values for each subject's deep and peripheral WM were caculated respectively and were plotted against postnatal age with scatter plot and linear regression model, and then did linear correlation and linear regression statiatical analysis. And then mean FA values from the nine ROIs for the same age subjects were caculated respectively, and then make Break Line Graph of Mean Fractional Anisotropy of Various Anatomical Parts inSame Group were plotted against age. Statistical treatment: Corresponding values for deep and peripheral WM structures and regions were evaluated with paired t~tests. For assessment of possible differences in the rate of maturation in peripheral WM and deep WM, the equality of the regression slopes was tested within the regression model with multivariate analysis of variance. P<0.05 we considered the diffetent to be statistically significant. statistically analysis all the data with SPSS16.0.Result:1.Mean FA values of cerebral white matter was increasing with age in the first postnatal year, but rate of rise was greater in the first 6 month of life than the rest of first year(P<0.05).2.Differences were observed in rates of maturation between peripheral WM and deep WM in the first 6 month of life, the former was less than the late.However, throughout the rest of the first year, the two rates of change was similar.3. Mean FA values of peripheral white matter was smaller than deep WM, peripheral WM was less mature than deep WM in the microscopic tissue structure according to the results of extrapolation of FA values in the first year of life (P<0.05).4.In the same group,Mean FA values of cerebral white maffer in different anatomical site was different in the first year of life(P<0.05). Mean FA values of same anatomical site of among groups is statistical significance(P<0.05).Conclusion: DTI showed the changes of brain tissue microstructure in vivo, with which normal changes in brain during infant can be evaluated .