高场强MR对孕中期胎儿小脑发育的显示

High-field magnetic resonance imaging evaluates development of the human fetal cerebellum

摘要目的：探讨胎儿小脑结构在不同场强MR图像上的显示情况。方法：48例孕龄在14-22周的胎儿标本，分别进行3．0T与7．0TMR头部扫描，选取不同场强与方位的MR图像，对比分析胎儿小脑结构的显示情况；使用Amira软件测量小脑体积，分析两种场强下获得的体积数值与孕龄的相关关系。结果：3．0T标本MR图像上，T1加权图像对小脑结构显示较T2加权图像清晰，尤其是在20周以后，并随孕龄增大成像分辨率增加。7．0TMR图像对胎脑发育结构的显示以20周前最佳且T2加权图像较T1加权图像效果好，图像质量随孕龄增大分辨率下降。由两种图像重建获得的小脑体积有差异，且其与孕龄的相关关系不同。结论：3．0TT1加权MR图像可以较好显示发育中的胎儿小脑结构；7．0TT2加权MR图像在20周前可以更加清晰显示这些结构。

Objective： To study the presentation of fetal brain of different gestational age （GA） on MRI. Methods： 48 fetal specimens that had no morphological brain disorder at 14-22 weeks of gestation were scanned under 3.0T MR and 7.0T MR. Amira 4.1 software was used to determine the cerebellar volume of the fetal cerebellum. The relationship between these measurements and GA was analyzed. Results： On T1 images of 3.0T MR, the cerebellums were more accurately identified after 20 GA, and they all got clearer as the GA increased. On T2 images of 7. 0T MRI before 20 GA, the fissures and the dentate nucleus could be shown clearly. Cerehellar volumes obtained from two different images were varied and exhibited different correlation with GA. Conclusion： T1 images of 3. 0T MR show the developing structures of post mortem fetal cerebellum well, but the T2 images of 7.0T MR show comparatively better before 20 GA.