The movement of blood inside the placenta enables transfer of nutrients and waste products between the maternal and fetal circulation. Because of the relatively high blood volume in the placenta, it can be easily investigated with Magnetic Resonance Imaging (MRI). Our aim is to develop a non-invasive imaging technique to measure in-vivo water exchange across the mouse placenta due to perfusion and/or magnetization transfer between water and large macromolecules.

Water exchange across the mouse placenta was measured using Arterial Spin Labeling (ASL), a common method in MRI that measures perfusion by perturbation of the arterial water using selective RF irradiation and then observing the transfer of this perturbation from the arterial water to the perfused organ. We observed areas especially inside the placenta and towards it,
showing a large degree of saturation transfer, most probably due to the high volume of moving blood within the placenta. Other than the placenta, also different regions within the fetus had different degrees of signal attenuation, showing that this method does not only measure the blood input to the whole placenta, but also the exchange between the maternal and fetal circulation.

This non-invasive tool for imaging and analysis of the water dynamics across the placenta can be implemented in the future for studies of growth restricted pregnancies.

Authors

Avni Reut, Garbow Joel, Neeman Michal
Weizmann Institute of Science, Rehovot, Israel