MRI和DTI评价早产儿脑白质髓鞘发育

Evaluation of white matter myelination in preterm infants using DTI and MRI

摘要:

目的 应用磁共振(MRI)、磁共振弥散张量成像(DTI)研究早产儿脑白质髓鞘发育的特点。方法 胎龄≤32周、出生体重<1 500 g的31例早产儿根据头部MRI检查分为早产脑损伤组(12例)和早产无脑损伤组(19例)。选取24例足月儿作为对照组。均于胎龄或纠正胎龄37~40周之间完成头部MRI及DTI检查。测定3组相同感兴趣区的部分各向异性参数(FA)和表观扩散系数(ADC)。结果 早产脑损伤组内囊后肢FA值小于早产无脑损伤组和足月对照组 (P < 0.05);早产脑损伤组和早产无脑损伤组的额叶白质和豆状核的FA值小于足月对照组 (P < 0.05);3组间枕叶白质的FA值差异无显著性 (P > 0.05)。早产脑损伤组和早产无脑损伤组内囊后肢、豆状核、枕叶白质、额叶白质的ADC值高于足月对照组 (P < 0.05)。结论 早产儿脑损伤容易出现内囊后肢深部脑白质髓鞘化障碍或延迟。早产儿至纠正胎龄足月时,无论有无脑损伤,脑周围白质及灰质成熟度均低于足月儿。

Abstract:

Objective To investigate the features of white matter myelin development in preterm infants using magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Methods A total of 31 preterm infants with a gestational age of ≤32 weeks and a birth weight of <1 500 g were enrolled. According to head MRI findings, these infants were divided into preterm group with brain injury (12 infants) and preterm group without brain injury (19 infants). A total of 24 full-term infants were enrolled as control group. Head MRI and DTI were performed at a gestational age or corrected gestational age of 37-40 weeks. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured for the same regions of interest in the three groups. Results The preterm group with brain injury showed a significantly lower FA value of the posterior limb of the internal capsule than the preterm group without brain injury and full-term control group (P < 0.05). The preterm groups with and without brain injury showed significantly lower FA values of frontal white matter and lenticular nucleus than the full-term control group (P < 0.05). The FA value of occipital white matter showed no significant differences among the three groups (P > 0.05). Compared with the full-term control group, the preterm groups with and without brain injury showed significantly higher ADC values of the posterior limb of the internal capsule, lenticular nucleus, occipital white matter, and frontal white matter (P < 0.05). Conclusions After brain injury, preterm infants tend to develop disorder or delay of white matter myelination in the posterior limb of the internal capsule. At a corrected full-term gestational age, the preterm infants with and without brain injury have a lower grade of maturity in periventricular white matter and grey matter than full-term infants.