Department of Obstetrics and Gynecology, Aalborg University Hospital, Reberbangade, Aalborg, Denmark.
Ultrasound Obstet Gynecol. 2013 Sep;42(3):310-4. doi: 10.1002/uog.12395.
To investigate changes in human placental oxygenation during maternal hyperoxia using non-invasive blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI).
Eight healthy pregnant women with uncomplicated singleton pregnancies at gestational weeks 28-36 were examined with BOLD MRI, over two consecutive 5-min periods of different oxygenation: first normoxia (21% O2 ) and then hyperoxia (12 L O2 /min), achieved by controlling the maternal oxygen supply with a non-rebreather facial mask. Selecting three slices showing cross-sections of the central part of the placenta, we investigated total placental oxygenation by drawing regions of interest (ROIs) covering the entire placenta, and regional placental oxygenation by drawing smaller ROIs in the darker and brighter areas of the placenta. For each ROI, the difference in BOLD signal between the two episodes was determined and the percentage increase in BOLD signal during hyperoxia (ΔBOLD) was calculated.
In the BOLD image, the normoxic placenta appeared heterogeneous, with darker areas located to the fetal side and brighter areas to the maternal side. During hyperoxia, the placenta became brighter and the structure more homogeneous, and the BOLD signal of the total placenta increased (ΔBOLDtot , 15.2 ± 3.2% (mean ± SD), P < 0.0001). The increase was seen predominantly in the dark areas in the fetal part of the placenta (ΔBOLDfet , 32.1 ± 9.3%) compared with in the bright areas in the maternal part of the placenta (ΔBOLDmat , 5.4 ± 3.5%).
During hyperoxia, placental oxygenation was increased predominantly in the darker placental areas, which, given their anatomical location, represent the fetal circulation of the placenta. To our knowledge, this is the first study to successfully visualize changes in placental oxygenation using BOLD MRI.
使用非侵入性血氧水平依赖（BOLD）磁共振成像（MRI）研究母体高氧血症期间人胎盘氧合的变化。
对 8 名孕 28-36 周、无并发症的单胎妊娠健康孕妇进行 BOLD MRI 检查，在两次连续的 5 分钟不同氧合期内：首先是常氧（21% O2 ），然后是高氧（12 L O2 /min），通过用非再呼吸面罩控制母体供氧来实现。选择显示胎盘中央部分横截面的三个切片，通过在胎盘的较暗和较亮区域绘制较小的 ROI，我们通过绘制覆盖整个胎盘的 ROI 来研究总胎盘氧合，并通过绘制 ROI 来研究区域胎盘氧合。对于每个 ROI，确定两个时间段之间 BOLD 信号的差异，并计算高氧期间 BOLD 信号的增加百分比（ΔBOLD）。
在 BOLD 图像中，常氧胎盘呈异质性，胎儿侧较暗，母体侧较亮。在高氧血症期间，胎盘变亮且结构更加均匀，总胎盘的 BOLD 信号增加（ΔBOLDtot ，15.2 ± 3.2%（均值 ± 标准差），P<0.0001）。与母体胎盘的亮区相比，增加主要发生在胎盘胎儿区的暗区（ΔBOLDfet ，32.1 ± 9.3%）。
在高氧血症期间，胎盘氧合主要在较暗的胎盘区域增加，鉴于其解剖位置，这些区域代表胎盘的胎儿循环。据我们所知，这是首次使用 BOLD MRI 成功可视化胎盘氧合变化的研究。
