MRI technique detects placental dysfunction in pregnant women

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An advanced magnetic resonance imaging technique has been successfully used to detect placental abnormalities in pregnancies complicated by fetal congenital heart disease before they become irreversible.

A research team at Children’s National Health System in Washington, DC, is the first to report non-invasive, whole placenta perfusion imaging in utero using the MRI technique—called velocity-selective arterial spin labeling (VSASL)—to provide an early warning of placental dysfunction.

The perfusion of the intervillous spaces of the placenta with maternal blood supplies a growing fetus with oxygen and nutrients, while transferring waste products and carbon dioxide back from the fetus to the mother. However, when the placenta malfunctions, it is unable to supply adequate oxygen and nutrients to the baby from the mother’s bloodstream, leading to low birth weight, premature birth, and birth defects such as congenital heart defects—which affects 8 in 1,000 newborns.

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As an advanced MRI technique, VSASL directly measures the rate of delivery of arterial blood to organs like the brain as well as tracks water molecules within the blood as it flows through arteries, eliminating the need to use a contrast agent.

In a study, 48 pregnant women underwent at least one fetal MRI session during their second or third trimester of pregnancy. Results of the study, published online in Scientific Reports, show that researchers were able to distinguish the placenta perfusion contributions by the fetus and the mother.

“In pregnancies complicated by fetal CDH, global placental perfusion significantly decreased and regional variation of placental perfusion significantly increased with advancing gestational age,” says lead author Zungho Zun in the Division of Diagnostic Imaging and Radiology at Children’s National Medical Center.

“Just like the human brain, heart and kidneys—organs that can commandeer heightened blood flow when needed—“the placenta may employ an auto-regulatory mechanism to optimize perfusion,” adds Catherine Limperopoulos, director of Children’s Developing Brain Research Laboratory and the study’s senior author. “The early increased global placental profusion in pregnancies complicated by CHD may represent an attempt to correct for insufficient fetal blood flow.”

According to the authors, the data from the study suggest that placental VSASL may serve as a potential biomarker of placental dysfunction in fetuses diagnosed with CHD, and that placental dysfunction due to CHD can be apparent as early as the second trimester of pregnancy using this imaging technology.

“The predictive value of VSASL imaging, which we continue to study, holds the promise of detecting dysfunction before placental abnormalities become irreversible,” concludes Limperopoulos.

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