应用单层厚块单次激发快速自旋回波序列产前显示胎儿畸形

Prenatal visualization of fetal anomaly with a single-shot thick-slab turbo spin-echo sequence

目的利用磁共振水成像的原理,采用单次激发厚层快速自旋回波(single-shot turbo spin echo,SSTSE)重T2加权序列行磁共振胎儿成像(magnetic resonance fetography,MRF),分析其成像质量及影响因素。评价其作为胎儿三维重建的一种替代方法的可行性。方法2006年4月至2008年2月间,因产前超声筛查诊断或怀疑胎儿存在先天性缺陷以及染色体检查异常的孕妇164例,169个胎儿,羊水正常137例,其中中孕38例,晚孕99例,羊水过多18例,羊水过少9例,羊水正常者头位胎104例,臀位胎29例,横位胎4例,在常规胎儿MRI检查基础上行MRF。对MRF图像进行质量评价,分析图像质量与孕周、胎位和羊水的关系及图像质量降低的原因。结果所有胎儿常规扫描和MRF成像均一次成功。51例胎儿体内的含液器官病理性扩张或萎陷,28例胎儿病理性积液,10例胎儿囊性病变,15例胎儿体表畸形和17例肢体畸形,以及16例母体肾盂积水和13例囊性病变在穿透胎儿表面后,也同时显示。MRF成像质量与胎儿孕龄、胎位、羊水量无统计学差异(P>0.05)。运动伪影、卷积伪影、母亲膀胱过度充盈可使图像质量降低。结论MRF提供了一种具有三维立体感的胎儿整体图像,能在1幅图像上同时捕捉胎儿的解剖和病理,具有快速、多方位、多视角、多次重复优质成像的特点,可以作为胎儿三维成像的一种替代方法。

Objective To analyze the image quality of magnetic resonance fetography with a single-shot thick-slab turbo spin-echo sequence, and to evaluate the potential of MRF in fetal magnetic resonance （MR） as an alternative to three-dimensional reconstructions. Methods From April 2006 to February 2008, 164 pregnant women with 169 fetuses underwent MR examinations for various indications （18th to 40^＋3 th gestational weeks） on a 1.5 T unit using a phased-array body surface coil after informed consent. Using our conventional protocol, this included thin multislice T2-weighted HASTE, true-FIST sequence and T1-weighted 2D FLASH sequence. A single-shot thick-slab （20 -100mm） turbo spin-echo was added to our conventional protocol. Resuits All our conventional protocol and single-shot thick-slab turbo spin-echo were performed successfully. It displayed that 51 fetuses were with pathological changes of fluid-filled cavities, 28 with pathological fluid accumulations, 10 with cystic mass, 15 with abnormal body surface, 17 with cacomelia 16 with maternal nephrydrosis and 13 with cystic disease, and ＂shining＂ through the fetal surface could be depicted. Pathological fluid accumulations could be delineated. There was no statistical difference of the quality of MRF among the groups of different gestational ages, fetal positions and amount of amniotic fluid （P 〉 0. 05）. Constructed defect due to motion and convolution, mothers＇ overfilling bladder could degrade the image quality. Conclusion MRF with thick-slab method offers a general overview of fetal pathologic or anatomic structure that may be captured in one image. The combination of overall appearance and translucency provides a new look of the fetus. MRF can quickly be repeated to get images at different orientations and different view angles. It can be used as an alternative to 3D reconstructions.