National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, M, United States.
U.S. Department of Health and Human Services, Eunice Kennedy Shriver National Institute of Child Hea, United States.
J Biomed Opt. 2020 Nov;25(11). doi: 10.1117/1.JBO.25.11.116001.
Placenta is an essential organ for fetal development and successful reproduction. Placental insufficiency can lead to fetal hypoxia and, in extreme cases anoxia, leading to fetal death. Of the 145 million deliveries per year worldwide, ∼15 million neonates are small for gestational age and, therefore, at risk for antepartum and intrapartum hypoxia. Clinical methods to assess placental function largely rely on the assessment of fetal heart rate changes but do not assess placental oxygenation. Near-infrared spectroscopy (NIRS) allows non-invasive, real-time assessment of tissue oxygenation in intact organs, which can be used to assess placental oxygenation. However, tissue optical properties can affect the accuracy of methods to measure tissue oxygenation.
This study was performed to estimate the scattering coefficient of the human placenta. We have computed the scattering coefficients of the human placenta for the range of 659 to 840 nm using two methods of diffuse reflectance spectroscopy (DRS).
Measurements were performed using an in-house DRS device and a well-established frequency-domain diffuse optical spectroscopic system (DOSI). Measurements were performed in eight placentas obtained after cesarean deliveries. Placentas were perfused with normal saline to minimize the effects of absorption due to blood. Three sites per placenta were measured. Absorption and scattering coefficients were then calculated from the measured reflectance using the random walk theory for DRS and frequency-domain algorithm for DOSI.
Average reduced scattering coefficient (μs ' ) was 0.943 ± 0.015 mm - 1 at 760 nm and 0.831 ± 0.009 mm - 1 at 840 nm, and a power function μs ' = 1.6619 (λ/500 nm) - 1.426 was derived for the human placental scattering coefficient.
We report for the first time the scattering coefficient of the human placenta. This information can be used to assess baseline scattering and improve measurements of placental oxygen saturation with NIRS.
胎盘是胎儿发育和成功繁殖的重要器官。胎盘功能不全可导致胎儿缺氧，在极端情况下可导致胎儿缺氧，导致胎儿死亡。在全球每年 1.45 亿次分娩中，[1500 万]新生儿为小于胎龄儿，因此有产前和产时缺氧的风险。评估胎盘功能的临床方法主要依赖于评估胎儿心率变化，但不能评估胎盘氧合作用。近红外光谱（NIRS）允许对完整器官的组织氧合进行非侵入性、实时评估，可用于评估胎盘氧合作用。然而，组织光学特性会影响测量组织氧合的方法的准确性。
本研究旨在估计人胎盘的散射系数。我们使用两种漫反射光谱（DRS）方法计算了 659 至 840nm 范围内人胎盘的散射系数。
使用内部 DRS 设备和成熟的频域漫射光学光谱系统（DOSI）进行测量。在剖宫产获得的 8 个胎盘上进行了测量。胎盘用生理盐水灌注以最大程度地减少血液引起的吸收影响。每个胎盘测量三个部位。然后使用随机漫步理论（DRS）和频域算法（DOSI）从测量的反射率计算吸收和散射系数。
在 760nm 处平均有效散射系数（μs′）为 0.943±0.015mm-1，在 840nm 处为 0.831±0.009mm-1，得出人胎盘散射系数的幂函数μs′=1.6619（λ/500nm）-1.426。
我们首次报告了人胎盘的散射系数。该信息可用于评估基线散射，并提高 NIRS 测量胎盘氧饱和度的能力。
