T2加权液体衰减反转恢复序列成像在定量评估无脑损伤早产儿脑白质发育中的价值

目的 利用T2加权液体衰减反转恢复(T2WI-FLAIR)序列成像评估无脑损伤早产儿脑白质发育情况.方法 收集2015年7月至2018年7月山东大学齐鲁儿童医院新生儿监护室收治的157例无脑损伤早产儿的MRI资料和临床资料,以33名足月新生儿作为对照.早产儿按出生胎龄分为28～29周、30～31周、32～33周、34～35周、36～37周5组.对各组早产儿出生后1～3 d内及纠正胎龄为40周时和足月新生儿胎龄40周时行头颅MRI T2WI-FLAIR序列成像,测量白质低信号区最大截面积及信号强度比值.比较不同出生胎龄组早产儿白质低信号区最大截面积及信号强度比值,以及各组早产儿纠正胎龄为40周与足月新生儿胎龄40周时的白质低信号区最大截面积及信号强度比值的差异,并分析不同出生胎龄组早产儿白质中央区、周围区及邻近脑室区信号强度比值的差异.结果 28～29周、30～31周、32～33周、34～35周、36～37周组早产儿白质低信号区最大截面积均随着出生胎龄的增加而降低,信号强度比值均随着出生胎龄的增加而升高(P均<0.01),信号强度比值均按照枕、顶、额、颞叶的顺序依次降低(P均<0.01).32～33周、34～35周、36～37周组早产儿白质低信号强度比值均按照中央区、周围区及邻近脑室区的顺序降低(P均<0.01).不同出生胎龄组早产儿在纠正胎龄为40周时白质低信号区最大截面积均随着出生胎龄的增加而降低,信号强度比值随着出生胎龄的增加而升高,差异均有统计学意义(P均<0.01).不同出生胎龄组早产儿在纠正胎龄为40周时白质低信号区最大截面积均大于足月新生儿胎龄40周时,信号强度比值均低于足月新生儿胎龄40周时(P均<0.01).结论 MRI T2WI-FLAIR序列成像能够定量评估无脑损伤早产儿脑白质的髓鞘化程度,是判断早产儿脑白质发育状况的一种重要的无创检查手段.

Value of T2 weighted-fluid attenuated inversion recovery sequence in quantitative assessment of white matter development in preterm infants without brain injury

Objective To evaluate the development of white matter in preterm infants without brain injury by T2 weighted-fluid attenuated inversion recovery (T2WI-FLAIR) sequence. Methods The magnetic resonance imaging (MRI) and clinical data of 157 preterm infants without brain injury admitted to the neonatal intensive care unit of Qilu Children''s Hospital of Shandong University from Jul. 2015 to Jul. 2018 and the corresponding data of 33 full-term newborns were collected. The preterm infants were divided into 5 groups according to the gestational age at birth:28-29, 30-31, 32-33, 34-35 and 36-37 weeks. Brain MRI with T2WI-FLAIR sequence was performed in preterm infants of each group within 1 to 3 days after birth and at 40 weeks of corrected gestational age, as well as in full-term newborns at 40 weeks of gestational age, measuring the maximum cross-sectional area and signal intensity ratio of low signal region in white matter. The differences of the maximum cross-sectional area and signal intensity ratio of low signal region in white matter were analyzed between the different gestational age groups and between preterm infants at 40 weeks of corrected gestational age in each group and full-term newborns at 40 weeks of gestational age. The differences of signal intensity ratios in the central, peripheral and adjacent ventricular regions of white matter in different gestational age groups were analyzed. Results The maximum cross-sectional areas of low signal region in white matter in preterm infants of 28-29, 30-31, 32-33, 34-35 and 36-37 week groups were decreased with the increase of the gestational age, the signal intensity ratios were increased with the increase of the gestational age (all P<0.01), and the signal intensity ratios were decreased in the order of occipital, parietal, frontal and temporal lobes (all P<0.01). The signal intensity ratios of low signal region in white matter with preterm infants in the groups of 32-33, 34-35 and 36-37 weeks were decreased in the order of central, peripheral and adjacent ventricular regions (all P<0.01). The maximum cross-sectional area of low signal region in white matter in preterm infants at 40 weeks of corrected gestational age was decreased significantly with the increase of the gestational age, and the signal intensity ratio was increased significantly with the increase of the gestational age (all P<0.01). The maximum cross-sectional area of low signal region in white matter of preterm infants in different gestational age groups at 40 weeks of corrected gestational age was significantly larger than that of the full-term newborns at 40 weeks, and the signal intensity ratio was significantly lower than that of the full-term newborns at 40 weeks (all P<0.01). Conclusion MRI with T2WI-FLAIR sequence can quantitatively evaluate the degree of myelination in preterm infants without brain injury, and it is an important non-invasive examination for the development of brain white matter in preterm infants.