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Fetal MRI

BOLD MRI in Fetal Mice

Brain sparing in fetal mice: using BOLD MRI to study blood redistribution during hypoxia

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BOLD MRI contrast and Doppler ultrasound are used to characterize the redistribution of fetal blood flow that occurs in healthy, pregnant mice under hypoxic conditions.

Summary

Severe fetal growth restriction (FGR) is often associated with a redistribution of blood flow to preserve oxygenation of the fetal brain at the expense of other fetal organs, the brain sparing effect.

Understanding the physiology of this brain sparing response may lead to better diagnostic procedures for predicting fetal risk, and help to optimize the timing of delivery in cases of FGR.

The oxygen content of the gas mixture inhaled by the dam was varied to simulate placental dysfunction.

As the maternal inspired gas mixture was varied between 100% and 8% oxygen, the BOLD signal intensity decreased by 46 ± 18% in the fetal liver and only by 12 ± 7% in the fetal brain.

Using Doppler ultrasound measurements, mean cerebral blood velocity was observed to rise by 18 ± 8% under hypoxic conditions.

These findings are consistent with active regulation of cerebral oxygenation and represent the first demonstration of brain sparing in fetal mice. 

Click to view full-sized image.
Click to view full-sized image.