Tag Archive for: functional connectivity magnetic resonance imaging

pregnant woman looking at sonogram

Babies with congenital heart disease display disrupted brain function before birth

pregnant woman looking at sonogram

In their study, the team at Children’s National Hospital found that specific brain regions become especially vulnerable to injury around 24 weeks of pregnancy when developing babies begin to have high energy demands and rapid neurovascular changes.

For the first time, researchers have found that babies born with congenital heart disease (CHD) have alterations to the emerging functional connectivity of their brains in utero. The changes are related to the subtype of their CHD and their oxygen status before they have lifesaving surgery to treat their cardiac malformation, according to new findings published in the American Heart Association’s Circulation Research.

In their study, the team at Children’s National Hospital found that specific brain regions become especially vulnerable to injury around 24 weeks of pregnancy when developing babies begin to have high energy demands and rapid neurovascular changes. That leaves certain parts of the brain, including the brainstem, more susceptible to injury from cardiac complications and poor circulation.

“We used a special type of magnetic resonance imaging to safely study the brains of these unborn babies, and we found that they have weakened connectivity in the deep grey structures, which are responsible for sensation, movement, alertness and other core functions,” said Josepheen De Asis-Cruz, M.D., Ph.D., assistant professor at the Developing Brain Institute at Children’s National and an author of the study. “This offers an important clue in utero to the type of care the babies will eventually need when they are born.”

The big picture

In the past decade, the survival rate for fetuses with CHD has greatly improved. About 80% of cases – even some of the most high-risk heart defects – can be successfully treated or palliated with surgery and survive. Yet Dr. Cruz said researchers are finding that the rates of poor neurodevelopmental outcomes are about the same. That’s why she and her colleagues are looking at what precisely may be injuring the brains of these newborns prior to surgery, offering a possible roadmap to interventions.

The fine print

The research team studied 107 healthy, low-risk pregnancies and 75 pregnancies known to be complicated by CHD. They used functional connectivity magnetic resonance imaging (fcMRI) to examine the emerging connections of the brains of unborn babies, given fcMRI’s unique ability to query the brain in a resting state when a patient is unable to respond to tasks. They also studied the oxygen saturation levels of the babies after they were born and then mapped all of this information to the type of CHD that they were diagnosed with.

“Our findings indicate that the compromised connectivity in the brains of CHD patients before delivery is linked to hypoxia after birth,” Cruz said. “There were important differences in the low- and high-risk CHD groups. Babies born with transposition of the great arteries or hypoplastic left heart syndrome – two of the most high-risk diagnoses – have notable changes in their brain function, which could someday be used as biomarkers to guide their care.”

What’s ahead

Researchers at Children’s National are working together, using a variety of modalities, to move toward precision imaging in utero to help predict a child’s neurodevelopmental outcomes. The ultimate goal: better interventions sooner.

“This work is foundational. As we fine-tune more techniques to identify babies at risk, we can understand how environmental, genetic and epigenetic factors impact brain development and guide care decisions,” said Catherine Limperopoulos, Ph.D., director of the Center for Prenatal, Neonatal & Maternal Health Research and a senior author of the paper. “We can imagine a day where we can offer pregnant mothers highly detailed and personalized information about their unborn baby, and individualized interventions that lead to healthier lifetimes.”

Catherine Limperopoulous

Brain impairment in newborns with CHD prior to surgery

Catherine Limperopoulous

Children’s National researchers led by Catherine Limperopoulos, Ph.D., demonstrate for the first time that the brains of high-risk infants show signs of functional impairment before they undergo corrective cardiac surgery.

Newborns with congenital heart disease (CHD) requiring open-heart surgery face a higher risk for neurodevelopmental disabilities, yet prior studies had not examined whether functional brain connectivity is altered in these infants before surgery.

Findings from a Children’s National Health System study of this question suggest the presence of brain dysfunction early in the lives of infants with CHD that may be associated with neurodevelopmental impairments years later.

Using a novel imaging technique, Children’s National researchers demonstrated for the first time that the brains of these high-risk infants already show signs of functional impairment even before they undergo corrective open heart surgery. Looking at the newborns’ entire brain topography, the team found intact global organization – efficient and effective small world networks – yet reduced functional connectivity between key brain regions.

“A robust neural network is critical for neurons to travel to their intended destinations and for the body to carry out nerve cells’ instructions. In this study, we found the density of connections among rich club nodes was diminished, and there was reduced connectivity between critical brain hubs,” says Catherine Limperopoulos, Ph.D., director of the Developing Brain Research Laboratory at Children’s National and senior author of the study published online Sept. 28, 2017 in NeuroImage: Clinical. “CHD disrupts how oxygenated blood flows throughout the body, including to the brain. Despite disturbed hemodynamics, infants with CHD still are able to efficiently transfer neural information among neighboring areas of the brain and across distant regions.”

The research team led by Josepheen De Asis-Cruz, M.D., Ph.D., compared whole brain functional connectivity in 82 healthy, full-term newborns and 30 newborns with CHD prior to corrective heart surgery. Conventional imaging had detected no brain injuries in either group. The team used resting state functional connectivity magnetic resonance imaging (rs-fcMRI), a imaging technique that characterizes fluctuating blood oxygen level dependent signals from different regions of the brain, to map the effect of CHD on newborns’ developing brains.

The newborns with CHD had lower birth weights and lower APGAR scores (a gauge of how well brand-new babies fare outside the womb) at one and five minutes after birth. Before the scan, the infants were fed, wrapped snugly in warm blankets, securely positioned using vacuum pillows, and their ears were protected with ear plugs and ear muffs.

While the infants with CHD had intact global network topology, a close examination of specific brain regions revealed functional disturbances in a subnetwork of nodes in newborns with cardiac disease. The subcortical regions were involved in most of those affected connections. The team also found weaker functional connectivity between right and left thalamus (the region that processes and transmits sensory information) and between the right thalamus and the left supplementary motor area (the section of the cerebral cortex that helps to control movement). The regions with reduced functional connectivity depicted by rs-fcMRI match up with regional brain anomalies described in imaging studies powered by conventional MRI and diffusion tensor imaging.

“Global network organization is preserved, despite CHD, and small world brain networks in newborns show a remarkable ability to withstand brain injury early in life,” Limperopoulos adds. “These intact, efficient small world networks bode well for targeting early therapy and rehabilitative interventions to lower the newborns’ risk of developing long-term neurological deficits that can contribute to problems with executive function, motor function, learning and social behavior.”