BOLD-MRI对高氧状态下胎盘氧合状况改变的初步探索

A preliminary study of changes in placental oxygenation during maternal hyperoxia with BOLD MRI

目的:探索BOLD-MRI技术对高氧状态下胎盘氧合功能的评估价值。方法:20例经产前超声检查具有胎儿畸形但胎盘正常的孕妇(孕周22周^(+1)~37周^(+3)),在行超声检查后2天内使用3TSiemens skyra MR仪行BOLD-MRI检查。孕妇前3min吸入空气,后7min持续吸入纯度大于90%的氧气(流速12L/min),采用面罩吸氧,吸气过程中边持续扫描10min,测量吸氧前后胎盘的BOLD信号差值,并采用配对t检验进行统计学分析。结果:20例胎盘的BOLD信号在前3分钟吸入空气的BOLD normoxia平均值为295.12,后7min吸入氧气后的BOLDhyperoxia平均值为323.88,吸氧后较吸氧前显著上升(△BOLD:10.7%±1.4%),吸氧前后的BOLD值差异有统计学意义(t=5.3471,P=0.00004)。结论:高氧状态下胎盘的BOLD信号增高,提示母体经胎盘向胎儿供氧的状况,也证明了BOLD-MRI技术可以用来检测胎盘的氧合功能,将来还可应用于胎盘功能下降所致的胎儿宫内发育迟缓的病例研究。

Objectives： To investigate the value of blood oxygen level-dependent （BOLD） mag- netic resonance imaging （MRI） in the evaluation of human placental oxygenation during maternal hy_ peroxia. Methods：Twenty pregnant women （gestational age between 22W＋1 to 37W＋3） with fetal mal- formations but normal placenta were examined by both conventional prental US （ultrasonography） and MRI examination. MRI examination of placenta was performed with a 3T Siemens skyra scanner within 2 days after US examination. During the 10 minutes with BOLD MRI scanning, pregnant women breathe room air in the first 3 minutes,followed by the hyperoxia breathe 02 （12L/min） with a facial mask lasting for 7 minutes. The changes in the BOLD MRI signals of p｜acenta were measured. Statistical analysis was performed using the paired t test. Results：The BOLD normoxia of the placenta was 295.12 in the first 3 minutes,323.88 in the followed 7 minutes,which was increased significantly during maternal hyperoxia （ABOLD： 10. 7% ± 1. 4%）. The differences were statistically significant between the differences of oxygenation levels （P = 0. 00004）. Conclusions： The hyperoxic placental BOLD response may reflect the maternal oxygen supply to the fetus though placenta. BOLD-MRI could be used to detect the oxygenation of placenta, and may be a potential application to the identifica- tion and understanding of placental dysfunction in fetal growth restriction.