Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA.
Fetal-Neonatal Neuroimaging & Developmental Sciences Center, Boston Children's Hospital, Boston, MA, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA, USA.
Placenta. 2020 Nov;101:4-12. doi: 10.1016/j.placenta.2020.07.026. Epub 2020 Aug 4.
Placental dysfunction plays a key role in diseases that affect the fetus in utero and after birth. Aiming to develop a platform for validating in vivo placental MRI and investigations into placental physiology, we designed and built a prototype MRI-compatible perfusion chamber with an integrated MRI receive coil for high SNR ex vivo placental imaging.
After optimizing placenta vascular clearing and perfusion protocols, we performed contrast enhanced MR angiography and MR relaxometry on eight carefully selected placentas while they were perfused via the umbilical arteries (UAs). Additionally, two of these placentas underwent maternal perfusion via the intervillous space (IVS). Despite striving for homogenous perfusion across the whole placenta, imaging results were highly heterogeneous for both UA and IVS perfused placentas. By histology, we observed blood congestion in the villi in regions that showed low UA perfusion during MRI. In two placentas prominent chorionic arteries followed by adjacent veins underwent contrast enhancement in the absence of villous capillary blush. The single placenta from a pregnancy affected by IUGR had the most homogeneous villous capillary perfusion.
A dual perfusion system for ex vivo placentas compatible with MRI permitted assessment of UA and IVS placental perfusion. We observed spatial UA perfusion heterogeneity and evidence for arteriovenous shunting in placentas from normal pregnancies and deliveries, but relative villous capillary perfusion homogeneity in a single IUGR placenta. Future work will focus on system optimization, followed by physiological manipulation and validation of in vivo placental MRI.
胎盘功能障碍在影响胎儿宫内和出生后疾病中起着关键作用。为了开发一种用于验证体内胎盘 MRI 和研究胎盘生理学的平台，我们设计并制造了一种具有集成 MRI 接收线圈的原型 MRI 兼容灌注室，用于高 SNR 的离体胎盘成像。
在优化胎盘血管清除和灌注方案后，我们对 8 个精心挑选的胎盘进行了对比增强磁共振血管造影和磁共振弛豫度测量，同时通过脐动脉（UA）对其进行灌注。此外，其中两个胎盘通过绒毛间隙（IVS）进行母体灌注。尽管我们努力使整个胎盘的灌注均匀，但 UA 和 IVS 灌注胎盘的成像结果高度不均匀。通过组织学观察，我们观察到在 MRI 期间 UA 灌注较低的区域绒毛充血。在两个胎盘中，明显的绒毛动脉及其相邻的静脉在没有绒毛毛细血管显影的情况下增强了对比。来自 IUGR 妊娠的单个胎盘具有最均匀的绒毛毛细血管灌注。
一种与 MRI 兼容的离体胎盘双灌注系统允许评估 UA 和 IVS 胎盘灌注。我们观察到正常妊娠和分娩胎盘的 UA 灌注空间异质性和动静脉分流的证据，但 IUGR 胎盘的相对绒毛毛细血管灌注均匀。未来的工作将集中在系统优化上，然后是生理操作和体内胎盘 MRI 的验证。
