正常胎儿大脑重要径线的MRI测量及意义

Measurements and significance of the major lines of normal fetal brain on MR images

目的探讨不同孕周（GA）MRI上正常胎儿头颅成像的脑额枕径（cFOD）、脑双顶径（CBD）及胼胝体长度（LCC）与孕周进展的生长规律。方法无中枢神经系统疾病的胎儿头颅MRI156例,胎龄24~38周,行1.5T MRI扫描,包括胎儿头颅横断位、冠状位及矢状位成像（Balance-FFE序列,T2WI-Drive序列）,分别测量cFOD、CBD、LCC,计算各指标在各孕周的中位数、最大值与最小值,并对各指标与孕周的关系进行相关与回归分析。结果 cFOD、CBD、LCC随孕周的进展而增加,三条径线随孕周的二次多项式函数拟合方程分别为：cFOD=-0.168（GA）2＋13.176GA-152.722（r2=0.813,P〈0.01）;CBD=-0.172（GA）2＋13.363GA-176.276（r2=0.834,P〈0.01）;LCC=-0.036（GA）2＋3.172GA-29.321（r2=0.640,P〈0.01）。结论 cFOD、CBD、LCC随孕周进展遵循二次多项式函数的变化趋势,胎儿大脑重要径线的MRI测量可为临床评估宫内胎儿大脑发育状况提供影像学依据。

Objective To measure three major lines of cerebral frontal-occipital diameter（cFOD）,cerebral biparietal diameter（CBD） and length of the corpus callosum（LCC） on MR images in normal fetal brain,and to analyze the relationship between those indexes and gestational age（GA）.Methods MR images of 156 fetal brain without any central nervous system diseases or abnormalities,aged from 24 to 38 gestational weeks,were retrospectively reviewed.All the images including transverse,coronal and sagittal images of the fetal brain were obtained by balance-FFE and T2WI-drive sequences on a 1.5 T MR scanner.cFOD,CBD and LCC were measured and the median,maximum and minimum values of those indexes in each gestational age were calculated.The relationships between those indexes and GA were analyzed using SPSS 13.0 statistical software.Results Regression functions were cFOD=-0.168（GA）2＋13.176GA-152.722 for cFOD（r2=0.813,P0.01）,CBD=-0.172（GA）2＋13.363GA-176.276 for CBD（r2=0.834,P0.01） and LCC=-0.036（GA）2＋3.172GA-29.321 for LCC（r2=0.640,P0.01）.Conclusion There are second-degree polynomial functional relationships between the median values of cFOD（mm）,CBD（mm） and LCC（mm） and GA（weeks）.Major morphologic indexes can provide valuable information for clinical evaluation of development status of fetal brain.