扩散张量成像在新生儿脑髓鞘发育中的初步研究

Diffusion tensor imaging for the development of neonatal brain myelin

目的应用磁共振扩散张量成像(diffusion tensor imaging,DTI)研究新生儿脑白质各向异性分数(fractional anisotropy,FA),探讨DTI在脑白质髓鞘发育中的应用价值.材料与方法收集行常规MRI和DTI扫描足月儿39例(胎龄37~42周)和早产儿61例(纠正胎龄至40周),围产史均正常,无神经系统疾病.分别测量各兴趣区的FA值,分析足月儿和早产儿的差异及其在脑内各部位白质的FA值差异.结果①左右半球相同部位的FA值差异无统计学意义(P>0.05).②早产儿和足月儿同部位FA值比较,内囊前后肢、胼胝体压部、半卵圆中心b区及外囊和小脑中脚区FA值两组比较差异有统计学意义(P<0.05).胼胝体膝部、侧脑室前角旁白质、侧脑室后角旁白质、半卵圆中心a区、室管膜下区的FA值两组比较差异无统计学意义(P>0.05).③早产儿和足月儿组内各白质区FA值不同,两两比较均发现内囊后肢高于前肢,侧脑室后角旁白质高于侧脑室前角旁白质,胼胝体压部高于膝部,各差异均有统计学意义(P<0.05).其中侧脑室前角旁白质FA值最低,胼胝体压部和内囊后肢FA值最高,两者比较差异均有统计学意义(P<0.05).结论 DTI的FA值可用于脑髓鞘发育成熟度的定量评价,早产儿和足月儿FA值差异提示早产儿脑内局部区域髓鞘成熟晚.不同区域FA值不同反映髓鞘形成时间的差异.

Objective: To investigate the fractional anisotropy (FA) in various brain regions of newborns and explore the value of diffusion tensor imaging (DTI) application in the cerebral white matter myelin development. Materials and Methods: 39 term neonates (gestational age in 37-42 weeks) and 61 premature infants (corrected to 40 weeks gestational age) were investigated by routine MRI and DTI. Their perinatal medical records and nervous system examinations showed no abnormalities. FA values were detected in the regions of interest. The differences of FA values between full term and preterm neonates were explored. Results:①FA values in the same regions of interest (ROI) had no statistic difference between left and right hemisphere (P>0.05).②The FA values between preterm infants and full term infants in same white matter regions were different. FA values in ALIC, CCS, external capsule (EC) were statistically higher than in PLIC, centrum semiovale (CS), and middle cerebellar peduncles (MCP)(P<0.05). The FA values of FPVZ were the lowest in all ROIs;and CCS and PLIC were highest. The comparison of between FPVZ and CCS, FPVZ and PLIC had significant difference respectively (P<0.05).③The FA values of premature and full term infants in various white matter regions were different and all values were compared in pairs. We found the values in posterior limb of internal capsule (PLIC) were higher than in anterior limb of internal capsule (ALIC), the values in occipital periventricular zone (OPVZ) were higher than in frontal periventricular zone (FPVZ), and corpus callosum splenium (CCS) were higher than corpus callosum genu (CCG). All the differences were statistically significant (P<0.05). Conclusions: FA values can be used to evaluate the myelination quantitatively. The different FA values in preterm and full term infants suggest late myelination in preterm infants. FA values reflects the difference of the myelination time.