快速MRI对胎儿中枢神经系统先天畸形的诊断价值与超声对照研究

目的 探讨快速MRI对胎儿中枢神经系统先天畸形的诊断价值并与超声（US）对照。方法 对48例孕妇产前行US和MRI检查，胎儿尸检及出生后随访检查证实中枢神经系统畸形22例，共26处。于US检查后3d内行胎儿颅脑脊柱及胸腹部MR扫描，并与US诊断结果和尸检及随访结果进行比较。结果 引产后尸检发现17处畸形，出生后随访检查证实9处畸形，共26处（无脑畸形6处、脊柱裂2处、脑膜脑膨出3处、先天性脑积水7处、前脑无裂畸形1处、脑穿通畸形3处、蛛网膜囊肿2处、脉络丛囊肿2处），US诊断24处，准确率92．3％（24／26），误、漏诊各1处，假阳性率3．8％（1／26），漏诊率为3．8％（1／26），MRI诊断23处，准确率88．5％，误诊1处，假阳性率3．8％（1／26），漏诊2处，漏诊率为7．7％（2／26）。比较2种方法差异无统计学意义（X^2=0．22，P〉0．05）。但快速MRI视野大，运动伪影少，组织分辨率高，能清楚显示脑灰白质、脑室系统、脑沟裂、蛛网膜下腔、脊柱等中枢神经系统解剖结构。结论 MRI对胎儿中枢神经系统先天畸形具有较高的诊断价值，可作为胎儿中枢神经系统先天畸形的一种重要的影像学诊断手段。

Fetal central nervous system anomalies: fast MRI vs ultrasonography

Objective To evaluate the ability of fast MRI to detect fetal central nervous system(CNS)anomalies and to compare its performance with that of prenatal ultrasonography(US).Methods Forty-eight pregnant women were detected by conventional prenatal US and MRI.Twenty-two fetuses with CNS anomalies were conformed by autopsy and follow-up.The MR and US appearances of fetal CNS structure were compared to each other and to that of autopsy.Results A total of 26 CNS anomalies were identified by autopsy(n=17)and follow-up(n=9)including anencephaly(n=6),rachischisis(n=2),encephalocele(n=3),congenital hydrocephalus(n=7),alobar holoprosencephaly(n=1),porencephalia(n=3),arachnoid cyst(n=2)and choroids plexus cyst(n=2).US diagnosed 24 CNS anomalies,the correct diagnostic rate was 92.3%,the false-positive rate was 3.8%,the missed-diagnostic rate was 3.8%.MRI diagnosed 23 CNS anomalies,the correct-diagnostic rate was 88.5%,the false-positive rate was 3.8%,the missed-diagnostic rate was 7.7%.There was no difference between US and MRI(P>0.05),but MRI have larger FOV,higher tissues resolution,and can demonstrate gray-white matter in detail.Conclusions MR imaging has a similar sensitivity to that of US in the detection of fetal CNS anomalies.