Amin R S, Nikolaidis P, Kawashima A, Kramer L A, Ernst R D
Department of Radiology, University of Texas Medical School, Houston, USA.
Radiographics. 1999 Oct;19 Spec No:S201-14. doi: 10.1148/radiographics.19.suppl_1.g99oc06s201.
Owing to recent advances in magnetic resonance (MR) imaging, the role of obstetric MR imaging has increased in cases in which the results of ultrasonography are equivocal. Fast MR imaging sequences, such as T2-weighted fast spin-echo (SE), half-Fourier single-shot fast SE, 0.5-signal-acquired single-shot fast SE, and echo-planar imaging, have virtually eliminated the need for fetal premedication, with a concomitant improvement in image resolution and diminished blurring. Artifacts related to maternal respiratory motion and fetal motion no longer limit the anatomic detail that can be demonstrated with MR imaging. With such advances in obstetric MR imaging, knowledge of normal fetal anatomy at MR imaging is essential to detect disease in utero. MR imaging can demonstrate fetal anatomy in detail, especially the brain, thorax, abdomen, pelvis, and vasculature. Major developmental structures of the fetus, particularly the cranial nervous system, naso- and oropharynx, lungs, and major abdominal viscera, can be adequately evaluated with targeted fast MR imaging as early as the beginning of the second trimester. However, MR imaging of the heart remains limited. Fetal MR imaging during the first trimester remains controversial secondary to biosafety issues and is limited due to diminutive fetal size.
由于磁共振（MR）成像技术的最新进展，在超声检查结果不明确的情况下，产科MR成像的作用有所增强。快速MR成像序列，如T2加权快速自旋回波（SE）、半傅里叶单次激发快速SE、0.5信号采集单次激发快速SE和回波平面成像，几乎消除了胎儿用药前准备的需要，同时提高了图像分辨率并减少了模糊。与母体呼吸运动和胎儿运动相关的伪影不再限制MR成像所能显示的解剖细节。随着产科MR成像技术的这些进展，了解MR成像时正常胎儿解剖结构对于检测子宫内疾病至关重要。MR成像可以详细显示胎儿解剖结构，尤其是脑、胸、腹、骨盆和脉管系统。早在孕中期开始时，通过靶向快速MR成像就可以充分评估胎儿的主要发育结构，特别是颅神经系统、鼻和口咽、肺以及主要腹部脏器。然而，心脏的MR成像仍然有限。由于生物安全问题，孕早期的胎儿MR成像仍然存在争议，并且由于胎儿体型小而受到限制。
