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(ΔBOLD: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) magnetic resonance imaging (MRI) in the evaluation of human placental oxygenation during maternal hyperoxia. Methods: Twenty pregnant women (gestational age between 22W+1 to 37W+3) with fetal malformations 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 placenta 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 (△BOLD: 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 identification and understanding of placental dysfunction in fetal growth restriction.
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