表观扩散系数评价宫内正常胎脑发育的初步研究

摘要

Objective To investigate the feasibility of ADC values in the evaluation of normal fetal brain development by measuring ADC values changes in specific regions with advancing gestational age.Methods Forty fetuses(gestational age:24 to 41 weeks) with normal brain underwent DWI(b value were 0 and 600 s/mm2).ADC values of the frontal white matter(WM),occipital WM,thalamus,basal ganglia,and cerebellum were measured by post-processing software.The differences among different regions' ADC values were calculated by repeated measurements of ANOVA,and simple linear regression was used to evaluate the relationship between ADC values and gestational age.Results The mean ADC valuesof 40 fetuses were(1 800±214) ×10-6mm2/s in frontal WM,(1 400±100) ×10-6mm2/s in basal ganglia,(1 300±126) ×10-6mm2/s in thalamus,(1 700±133) ×10-6mm2/s in occipital WM and(1 400± 155) × 10-6mm2/s in cerebellum,respectively.There was significant difference in the ADC values among the five regions(F=80.813,P＜0.01).In pair-wise comparison,ADC values of basal ganglia,thalamus and cerebellum had no significant difference; however,others had significant difference between each other.With the increasing gestational age,ADC values of basal ganglia,thalamus,occipital WM and cerebellum decreased,and had significant negative correlations with gestational age(Pearson correlation coefficient were-0.568,-0.716,-0.830 and-0.700,respectively,all P＜0.01).In terms of ADC value,occipital WM declined fastest with gestational age,followed by cerebellum and thalamus,and the slowest was basal ganglia.Frontal ADC values showed no correlation with gestational age(P＞0.05).Conclusions Specific regions of fetal brain have specific ADC values,and ADC values of the region undergo regular change with advancing gestational age.ADC value is a specific quantitative parameter that could help to evaluate normal brain development and early diagnosis of fetal brain lesions.%目的 通过对不同孕周的正常胎脑不同区域ADC值进行测量,探讨其评价正常胎儿脑发育的可行性.方法 对40例孕周为24～41周的正常胎脑进行DWI扫描,b值为0和600 s/mm2,通过后处理软件测量胎儿颅脑额叶白质、基底节区、丘脑、枕叶白质以及小脑的ADC值,然后使用重复测量方差分析及一元线性回归对不同区域ADC值与随孕周变化的关系进行分析.结果 40名正常胎脑的整体额叶白质、基底节区、丘脑、枕叶白质及小脑半球的平均ADC值分别为(1 800±214)×10-6、(1 400±100) ×10-6、(1 300±126) ×10-6、(1 700±133)×10-6及(1 400±155)×10-6mm2/s,差异具有统计学意义(F=80.813,P＜0.01).两两比较显示,除基底节区与丘脑和小脑半球的平均ADC值差异没有统计学意义外,其他两两差异均具有统计学意义.随着孕周的增加,基底节区、丘脑、枕叶白质以及小脑半球的ADC呈下降的趋势,其与孕周具有负相关(Pearson相关系数分别为-0.568、-0.716、-0.830和-0.700,P值均＜0.01).枕叶白质ADC值随孕周增加下降最快,小脑及丘脑次之,基底节区最慢;额叶白质的ADC值与孕周没有相关性(P＞0.05).结论 胎脑不同区域ADC值具有特异性,并且ADC值与孕周的发展变化具有相关性,可以作为定量评价正常颅脑发育以及早期诊断胎儿颅脑病变的特征性参数.