| Part Ⅰ Diffusion Tensor Imaging Study of Normal Neonatal Brain MaturationObjective The purpose of this study was to investigate the developing status and characteristics of cerebral white matter during the neonatal period by using diffusion tensor imaging technique.Methods In this study, 38 newborns were selected, including eighteen preterm infants(appropriate for gestational age) and twenty term infants(normal birth weight), they were divided into three groups according to their gestational age, fractional anisotropy obtaining from each region of interest were analyzed.Results The differences of FA values between left and right hemispheric white matter were not no significant statistically. FA values for the peripheral white matter regions were lower than the values for deep white matter structures,in the deep white matter, The splenium of corpus callosum showed larger FA than genu, and the anterior limb of internal capsule showed smaller FA than posterior limb of internal capsule, the FA values for the splenium was higher than the values for the posterior limb of internal capsule. Among peripheral white matter, FA in central white matter(the level of central semiovale) were the highest, no significant differences were observed between anterior and posterior white matter(the level of central semiovale)(all P>0.05). FA values for all measured regions in group was more than Ⅲthat values in groupⅠ, and the differences were significant statistically(all P<0.05), comparison between adjacent groups,there were significant statistically only in part of regions of interest.Conclusion Diffusion tensor imaging technique is very usefull in the study of neonatal white matter maturation, FA value can assess myelin development quantitatively.Part Ⅱ Diffusion tensor imaging combined with DWI and MRI study of newborns with hypoxic-ischemic encephalopathy in early diagnosis and prognosis evaluationObjective Our objective was to assess the value of diffusion tensor imaging and diffusion weighted imaging in detecting hypoxic-ischemic encephalopathy(HIE) in preterm infants, and explore the correlation between apparent diffusion coefficient(ADC), fractional anisotropy(FA) and Gesell scores of infants with HIE.Methods Eighteen newborns with HIE were selected, fifteen normal preterms were stratified to control group, all patients and normal newborns underwent MRI, DTI and DWI within 7 days after birth, ADC and FA values obtained from posterior limb of internal capsule, the splenium of corpus callosum, lenticular nucleus, ventral lateral nucleus of thalamus, the center of corona radiata and brainstem, and using the Gesell developmental scale to evaluate brain development at 3 months’ corrected age.Results Compared with control group, FA values in posterior limb of internal capsule, the splenium of corpus callosum, lenticular nucleus and the center of corona radiata of infants with HIE were significantly lower(P<0.05), except brainstem and ventral lateral nucleus of thalamus. The newborns with HIE showed smaller ADC than control group, except brainstem and ventral lateral nucleus of thalamus, and there was significant differences between control and injury group observed in posterior limb of internal capsule and the splenium of corpus callosum(P<0.05). The Gesell scores of infants with HIE were smaller than the control group’s, and a significant difference was found between these two groups, there was no correlation between ADC and FA values for each area of interest and Gesell scores(P>0.05), except the center of corona radiata and ventral lateral nucleus of thalamus.Conclusion ADC and FA values can assess HIE objectively, These differences of ADC values between injury neonates and normal neonates were only located in posterior limb of internal capsule and the splenium of corpus callosum, so the accuracy of ADC value in the diagnosis of premature HIE is lower than FA value, Gesell score has important value in evaluating the prognosis of infants with HIE, but has no correlation with ADC values and FA values. |
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