胎儿结肠三维磁共振成像研究

Three dimensional magnetic resonance imaging of fetal colon

目的:探讨三维磁共振成像技术(3D-MRI)在显示胎儿结肠正常解剖和病变方面的临床应用价值。方法:对38例孕19～37周经超声诊断或怀疑胎儿畸形的孕妇在超声检查后1～2 d内进行MRI检查,使用单次激发快速自旋回波序列(SSFSE)行胎儿矢状面和冠状面常规扫描,三维快速扰相梯度回波序列(3D-FSPGR)行胎儿三维磁共振结肠成像(3D-MRC),对三维原始数据进行多平面重组(MPR)、容积再现(VR)、最大密度投影(MIP)及MR仿真结肠镜(MRVC)等后处理,并测量各孕周胎儿正常结肠体积和结肠横径。并将MRI、超声和尸检及随访结果进行对比分析。结果:一次屏气3D-MRC采集时间10～14s,图像重组时间5～10min,本组中3D-MRC成功率达89.47%(34/38)。结肠在3D-MRC上表现为明显高信号,MPR、VR和MIP模式可以清楚显示不同孕周胎儿正常结肠走形、结肠袋和纡曲折叠部分。MPR可对兴趣区进行多角度的观察,MRVC可观察结肠内腔。孕19～37周胎儿正常结肠体积为5.1～69.2 ml,胎儿期正常结肠横径<1.8 cm。3D-MRC对结肠闭锁、先天性巨结肠、先天性膈疝及泄殖腔外翻畸形等复杂畸形具有较高的诊断价值。结论:胎儿3D-MRC在临床上是可行的,3D-MRC可显示胎儿结肠正常结构和病变,对于产前咨询和围产期手术具有重要的临床价值。

Objective：To investigate the clinical value of three dimensional magnetic resonance imaging（3D-MRI） in displaying the normal and abnormal fetal colon.Methods：Thirty-eight pregnant women（gestational age ranged from 19~37 weeks,with a mean of 28.5 weeks） diagnosed or suspected of having fetal malformations underwent conventional prenatal US and MRI.Sagittal and coronal SSFSE T2WI examinations at a 1.5T GE MR scanner within 1~2 days after US examinations were performed.Three dimensional magnetic resonance colonography（3D-MRC） was performed with three dimensional fast spoiled gradient echo（3D-FSPGR）.Volume rendering（VR）,maximum intensity projection（MIP）,multi-planar reconstruction（MPR） and MR virtual colonoscopy（MRVC） were employed in image post-processing on a dedicated workstation.The volume of normal colon between 19 weeks and 37 weeks was measured.The MRI and US appearances of fetal malformations were compared to each other,also correlated with autopsy and follow-up results.Results：The acquisition time and reconstruction time of 3D-MRC during a single breath-hold was 10~14 seconds and 5~10min,respectively.The successful rate was up to 89.47%（34/38）.Fetal colon showed high signal intensity on 3D-MRC,similar to the findings obtained by barium enema in neonates.MPR,VR and MRVC could clearly display normal colonic topography,haustra of colon and flexures.The region of interest could be viewed from various directions by using MPR.Dilatation and stenosis of intestinal lumen were displayed by using MRVC.The range of colon volumes between 19 and 37 weeks was 5.1~69.2ml.The transverse diameter of colon during fetal period was lesser than 1.8cm.Colonic atresia（3 cases）,congenital left diaphragmatic hernia（3 cases）,and congenital magacolon（2 cases） as well as cloacal exstrophy（1 case） were detected and diagnosed by 3D-MRC.Conclusion：3D-MRC is feasible in clinical practice,which is helpful for antepartum console and planning of fetal surgery.