MRI在显示胎儿中枢神经系统发育畸形中优势的初步探讨

目的:探讨MRI在检出胎儿中枢神经系统发育异常中的优势。方法:对42例超声检查发现胎儿异常的孕妇进行胎儿MRI检查(超声检查48h内完成),孕妇年龄22~35岁,胎龄16~35周。MRI检查采用半傅立叶单激励快速自旋回波(HASTE)序列获得T2WI,其中8例还行快速小角度激励(fastlowangleshot,FLASH)T1WI成像,4例行扩散加权成像。将超声结果、MRI与尸体解剖、手术或/和出生后随访MRI比较。结果:产前超声漏诊的病例共20例,MRI的T2WI仅漏诊1例。超声漏诊病例多数为脑实质及脊髓病变,且多种中枢神经系统发育畸形的声像图可表现相同,缺乏特异性。结论:MRI可直接显示脑实质、脊髓以及病变与脑脊髓的关系,在超声检查基础上进行胎儿磁共振成像,有助于弥补超声之不足,进一步完善、验证、甚至更正超声诊断。

Advantages of MRI in Demonstration of Fetal Central Nervous System Anomalies

Objective:To explore the advantages of MRI on demonstration of fetal central nervous system anomalies.Methods:Fouty-two women with complicated pregnancies,age from 22 to 35 years,gestation from 16~36 weeks,were stu- died with a 1.5T superconductive MR unit within 48h after ultrasound (US) studies.Half-Fourier acquisition single-shot turbo spin-echo (HASTE) T_2-weighted imaging (T_2WI) sequences were performed in all patients,and fast low angle shot (FLASH) T_1-weighted imaging (T_1WI) sequences were applied sequentially in eight of them.Comparison of the results was made between the MRI and US findings as well as autopsy or postnatal follow-up MRI findings.Results:Twenty cases and only one case were made missed diagnoses by US and MRI respectively.US had limits and low specificity to demonstrate anomalies of fetal central nervous system (especially in fetal brain tissue and spinal cord).Conclusion:MR has advantages in displaying fetal central nervous system anomalies than ultrasound,MR imaging is a valuable complement to sono- graphy in difficult cases,it can conplete,confirm,even correct the diagnosis made by ultrasound.