Real-Time Monitoring of Placental Oxygenation during Maternal Hypoxia and Hyperoxygenation Using Photoacoustic Imaging

Abstract

PurposeThis preclinical study aimed to evaluate placental oxygenation in pregnant rats by real-time photoacoustic (PA) imaging on different days of gestation and to specify variations in placental oxygen saturation under conditions of maternal hypoxia and hyperoxygenation.Material and methodsPlacentas of fifteen Sprague-Dawley rats were examined on days 14, 17, and 20 of pregnancy with a PA imaging system coupled to high-resolution ultrasound imaging. Pregnant rats were successively exposed to hyperoxygenated and hypoxic conditions by changing the oxygen concentration in inhaled gas. Tissue oxygen saturation was quantitatively analyzed by real-time PA imaging in the skin and 3 regions of the placenta. All procedures were performed in accordance with applicable ethical guidelines and approved by the animal care committee.ResultsMaternal hypoxia was associated with significantly greater decrease in blood oxygen saturation (ΔO2 Saturation) in the skin (70.74% ±7.65) than in the mesometrial triangle (32.66% ±5.75) or other placental areas (labyrinth: 18.58% ± 6.61; basal zone: 13.13% ±5.72) on different days of pregnancy (P<0.001). ΔO2 Saturation did not differ significantly between the labyrinth, the basal zone, and the decidua. After the period of hypoxia, maternal hyperoxygenation led to a significant rise in oxygen saturation, which returned to its initial values in the different placental regions (P<0.001).ConclusionsPA imaging enables the variation of blood oxygen saturation to be monitored in the placenta during maternal hypoxia or hyperoxygenation. This first preclinical study suggests that the placenta plays an important role in protecting the fetus against maternal hypoxia.

Photoacoustic imaging for in vivo quantification of placental oxygenation in mice

“…Our current study showing that lower FiO 2 is associated with lower placental sO 2 suggests good sensitivity of PAI for sO 2 measurements in vivo both in superficially located vasculature and in vivo in organs located in the abdominal cavity. Our findings also agree with a recently published study that reported a change in placental oxygenation in response to changes in maternal O 2 from 100 to 5%; however, it appears that the authors were only able to image a part of the placenta using 2-dimensional mode (26).…”

Oxygen and lack of oxygen in fetal and placental development, feto–placental coupling, and congenital heart defects

“…Blood oxygen level dependent (BOLD) MRI has been used to investigate O 2 saturations during gestation in larger animals and humans (Sorensen et al, ), but is not routinely applicable, especially in smaller laboratory animals. Photo‐acoustic imaging (PAI) was recently developed and tested in rat and mouse pregnancies (Arthuis et al, ; Yamaleyeva et al, ). PAI combines the optical contrast of photoacoustic laser technology with the low acoustic scattering and high spatial resolution of microultrasound (reviewed in the study by Beard, ).…”

Quantification of Multispectral Photoacoustic Images: Unsupervised Unmixing Methods Comparison

“…The commercial system Vevo LAZR (Visualsonics, Fujifilm) was used for multispectral photoacoustic acquisitions. The optical source was a Nd:YAG pulsed laser with pulse duration of 5 ns and 20 Hz repetition rate coupled with an optical parametric oscillator to access various wavelengths [10]. The acquisitions were based on the LZ400 probe ( Fig.…”