探讨新生儿及儿童脑白质发育的磁共振成像(magnetic resonance imaging，MRI)信号的表观弥散系数(apparent diffusion coefficient, ADC)均值变化。

选择2006年12月至2008年1月在本院采取3.0T磁共振检查的100例正常新生儿及儿童为研究对象，将其按照年龄分为A1组(n＝7，<1个月)，A2组(n＝18，1个月～1岁)，A3组(n＝6，1～2岁), A4组(n＝23，2～5岁)，A5组(n＝24，5～10岁)，A6组(n＝22，10～15岁)。为观察从儿童到青年过渡时期脑白质发育的磁共振成像信号表观弥散系数，另将14例15～20岁青少年纳入B组进行研究(本研究遵循程序符合本院人体试验委员会所制定的伦理学标准，得到该委员会批准，分组征得受试者监护人或本人知情同意，并与之签署临床研究知情同意书)。用3.0T磁共振机进行弥散加权成像(diffusion-weighted imaging, DWI)扫描，在脑室周缘脑白质取6个感兴趣区(regions of interest, ROI)进行表观弥散系数测量，并取表观弥散系数均值进行分析。

①新生儿及儿童的顶叶脑白质表观弥散系数均值与年龄增长呈明显负相关，其降低趋势在2岁前较明显，2岁后仍持续下降，但下降趋势明显减缓。②相同年龄，不同性别的正常新生儿及儿童侧脑室周缘脑白质表观弥散系数均值比较，仅A4组差异有显著意义(P＝0.043)，其他5组及总体男、女儿童的表观弥散系数均值比较，差异无显著意义(P>0.05)。③114例正常新生儿、儿童及青少年的侧脑室周缘脑白质左、右两侧表观弥散系数均值(左侧为1039.319×10^－5 mm²/s，右侧为1026.295 ×10^－5 mm²/s)比较，差异无显著意义((t＝0.613, P>0.05)。

表观弥散系数均值作为磁共振成像的定量指标，其变化可反映脑白质发育过程变化。表观弥散系数均值变化，可早于常规磁共振成像变化。

To study mean value change of magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) in white matter development of neonates, children and teenagers.

From December 2006 to January 2008, 100 normal neonates and children were included into study(group A). They were classified into six groups according to their age: A1 group (n=7, less than 1 month), A2 group (n=18, 1 month to 1 year old), A3 group (n=6, 1 to 2 years old), A4 group (n=23, 2 to 5 years old), A5 group (n=24, 5 to 10 years old), and A6 group (n=22, 10 to 15 years old). Another 14 children aged from 15 to 20 years old were selected into group B. Informed consent was obtained from all participants. Both of two groups were examined by MR scanner (Siemens Sonata 3.0 T) on brain with diffusion-weighted imaging (DWI), and the mean value of the apparent diffusion coefficient was acquired by measuring six different regions of interest (ROI) in periventricular white matter in each age group.

①There was an obvious negative correlation between age and mean value of the apparent diffusion coefficient of white matter of parietal lobe in neonates and children. The negative correlation was strong before 2-year-old, while it became mild after 2-year-old. ② Gender was not a strong factor in the mean value of the apparent diffusion coefficient change. Mean value of the apparent diffusion coefficient of periventricular white matter in neonates and children with same age and different gender were compared. Only group A4 (2 to 5 years old) showed a significant difference (P=0.043). There had no significant differences in other groups or all the testers(P>0.05). ③ The left mean value of the apparent diffusion coefficient in 114 normal neonates, children and teenagers was 1039.319×10^-5mm²/s, and the right mean value was 1026.295×10^-5 mm²/s. There was no significant difference between both sides(t=0.613, P>0.05).

The mean value of apparent diffusion coefficient could be regarded as a quantification index to reveal brain white matter changes during development. The mean value of the apparent diffusion coefficient change was previous to routine magnetic resonance imaging change.