Eight of every 1,000 children born each year have congenital heart disease (CHD). Although recent advances have greatly improved the survival of these children, up to 55 percent will be left with injury to their brain’s white matter – an area that is critical for aiding connection and communication between various regions in the brain. The resulting spectrum of neurological deficits can have significant costs for the individual, their family and society. Although studies have demonstrated that white matter injuries due to CHD have many contributing factors, including abnormal blood flow to the fetal brain, many questions remain about the mechanisms that cause these injuries and the best interventions.
A Children’s National Health System research team combed existing literature, reviewing studies from Children’s as well as other research groups, to develop an article detailing the current state of knowledge on CHD and white matter injury. The scientists write that advances in neuroimaging – including magnetic resonance imaging, magnetic resonance spectroscopy, Doppler ultrasound and diffusion tensor imaging – have provided a wealth of knowledge about brain development in patients who have CHD. Unfortunately, these techniques alone are unable to provide pivotal insights into how CHD affects cells and molecules in the brain. However, by integrating animal models with findings in human subjects and in postmortem human tissue, the scientists believe that it will be possible to find novel therapeutic targets and new standards of care to prevent developmental delay associated with cardiac abnormalities.
For example, using a porcine model, the Children’s team was able to define a strategy for white matter protection in congenital heart surgery through cellular and developmental analysis of different white matter regions. Another study from Children’s combined rodent hypoxia with a brain slice model to replicate the unique brain conditions in neonates with severe and complex congenital heart disease. This innovative animal model provided novel insights into the possible additive effect of preoperative hypoxia on brain insults due to cardiopulmonary bypass and deep hypothermic circulatory arrest.
The Children’s research team also recently published an additional review article describing the key windows of development during which the immature brain is most vulnerable to CHD-related injury.
Questions for future research
Q: Can we create an animal model that recapitulates the morphogenic and developmental aspects of CHD without directly affecting other organs or developmental processes?
Source: Reprinted from Trends in Neurosciences, Vol. 38/Ed. 6, Paul D. Morton, Nobuyuki Ishibashi, Richard A. Jonas and Vittorio Gallo, “Congenital cardiac anomalies and white matter injury,” pp. 353-363, Copyright 2015, with permission from Elsevier.
Diagnostic Imaging and Radiology
A new three-year, multi-million dollar research and education collaboration in maternal, fetal and neonatal medicine aims to improve the health of pregnant women and their children. The partnership between Children’s National Health System and Inova will yield a major, nationally competitive research and academic program in these areas that will leverage the strengths of both health care facilities and enhance the quality of care available for these vulnerable populations.
The collaboration will streamline completion of retrospective and prospective research studies, shedding light on a number of conditions that complicate pregnancies. It is one of several alliances between the two institutions aimed at improving the health and well-being of children in Northern Virginia and throughout the region.
“The Washington/Northern Virginia region has long had the capability to support a major, nationally competitive research and academic program in maternal and fetal medicine,” says Adre du Plessis, M.B.Ch.B., Director of the Fetal Medicine Institute at Children’s National and a co-Principal Investigator for this partnership. “The Children’s National/Inova maternal-fetal-neonatal research education program will fill this critical void.
“This new partnership will help to establish a closer joint education program between the two centers, working with the OB/Gyn residents at Inova and ensuring their involvement in Children’s National educational programs and weekly fetal case review meetings,” Dr. du Plessis adds.
Larry Maxwell, M.D., Chairman of Obstetrics and Gynecology at Inova Fairfax Medical Campus and a co-Principal Investigator for the collaboration, further emphasizes that “Inova’s experience in caring for women and children — combined with genomics- and proteomics-based research — will synergize with Children National’s leadership in neonatal pediatrics, placental biology and fetal magnetic resonance imaging (MRI) to create an unprecedented research consortium. This will set the stage for developing clinically actionable interventions for mothers and babies in metropolitan District of Columbia.”
Children’s National, ranked No. 3 nationally in neonatology, has expertise in pediatric neurology, fetal and neonatal neurology, fetal and pediatric cardiology, infectious diseases, genetics, neurodevelopment and dozens of additional pediatric medical subspecialties. Its clinicians are national leaders in next-generation imaging techniques, such as MRI. Eighteen specialties and 50 consultants evaluate more than 700 cases per year through its Fetal Medicine Institute. In mid-2016, Children’s National created a Congenital Zika Virus Program to serve as a dedicated resource for referring clinicians and pregnant women. The hospital performs deliveries in very high-risk, complex situations, but does not offer a routine labor and delivery program.
Inova Fairfax Medical Campus is home to both Inova Women’s Hospital and Inova Children’s Hospital. Inova Women’s Hospital is the region’s most comprehensive and highest-volume women’s hospital — delivering more than 10,000 babies in 2016. Inova Children’s Hospital serves as Northern Virginia’s children’s hospital —providing expert care in pediatric and fetal cardiology, cardiac surgery, genetics, complex general surgery, neurology, neurosurgery and other medical and surgical specialties. Its 108-bed Level IV neonatal intensive care unit is one of the largest and most comprehensive in the nation. Inova’s Translational Medicine Institute includes a genomics lab, as well as a research Institute focused on studies designed to build genetic models that help answer questions about individual disease. Each of these specialties is integrated into the Inova Fetal Care Center — which serves as a connection point between Inova Women’s and Children’s Hospitals. The Inova Fetal Care Center provides complex care coordination for women expecting infants with congenital anomalies or with other fetal concerns. Because Inova Women’s Hospital and Inova Children’s Hospital are co-located, women are able to deliver their babies in the same building where their children will receive care.
The research collaboration will support research assistants; tissue technicians; a placental biologist; as well as support for biomedical engineering, fetal-neonatal imaging, telemedicine, regulatory affairs and database management. The joint research projects that will take place under its auspices include:
- Fetal growth restriction (FGR), which occurs when the failing placenta cannot support the developing fetus adequately. FGR is a major cause of stillbirth and death, and newborns who survive face numerous risks for multiple types of ailments throughout their lives. A planned study will use quantitative MRI to identify signs of abnormal brain development in pregnancies complicated by FGR.
- Placental abnormalities, including placenta accreta. A planned study will combine quantitative MRI studies on the placenta during the third trimester and other points in time with formal histopathology to identify MRI signals of placenta health and disease.
- Microcephaly, a condition that is characterized by babies having a much smaller head size than expected due to such factors as interrupted brain development or brain damage during pregnancy. While the global Zika virus epidemic has heightened awareness of severe microcephaly cases, dozens of pregnancies in the region in recent years have been complicated by the birth defect for reasons other than Zika infection. A planned study will examine the interplay between MRI within the womb and head circumference and weight at birth to examine whether brain volume at birth correlates with the baby’s developmental outcomes.
A new Practice Guideline Summary published in Neurology, the journal of the American Academy of Neurology, contains the first complete, objective assessment of available data on the efficacy of functional magnetic resonance imaging (fMRI) to assess baseline language and memory, brain hemisphere dominance and to predict postsurgical impacts prior to surgery in patients with epilepsy.
According to contributing author William D. Gaillard, M.D., chief of Child Neurology, Epilepsy and Neurophysiology, and director of the Comprehensive Pediatric Epilepsy Program at Children’s National Health System, the report outlines several cases in which fMRI presents an effective alternative to the current standard of care, intracarotid amobarbital procedure (IAP). In IAP, medication is injected through the carotid artery to isolate one hemisphere of the brain at a time, followed by the patient performing memory or language tasks. The approach requires catheterization via a major artery. While minimally invasive, the procedure still carries the standard risks of vascular catheter procedures and requires recovery time.
“This publication took six years to complete,” Dr. Gaillard notes, “but we are happy to finally have the practice parameters that will make the case for the use of fMRI in an evidence-based way.”
Though the Practice Guidelines focus on adults, the evidence assessment included all available pediatric data as well, says Dr. Gaillard. A great deal of that data were contributed by Children’s National faculty, who lead the nation in clinical applications of fMRI. More than 20 years ago, Dr. Gaillard and his team began studying fMRI as a viable alternative to IAP to collect accurate language assessments in children, particularly those with epilepsy. Today, Children’s National is at the forefront of clinical application of fMRI, having performed about 1,000 pediatric assessments in the last two decades — more than nearly every other institution.
An 11-member panel of international experts conducted the analyses for the Practice Guidelines. Overall, the report indicates:
- fMRI is a viable option for measuring lateralized language functions in place of IAP in medial temporal lobe epilepsy, temporal epilepsy in general or extratemporal epilepsy.
- Evidence was insufficient to recommend fMRI over IAP for patients with temporal neocortical epilepsy or temporal tumors.
- Pre-surgical fMRI can serve as an adequate alternative to IAP memory testing for predicting verbal memory outcome.
In closing, the authors also explicitly recommend that clinicians carefully advise every patient of the risks and benefits of both fMRI and IAP before recommending either approach.
Related resources: Use of fMRI in the presurgical evaluation of patients with epilepsy
According to a large international study published in the American Journal of Medical Genetics, physical features vary in patients with Down syndrome across diverse populations. The study, led by the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, used an objective digital facial analysis technology developed by the Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National Health System to identify the most relevant facial features characteristic in Down syndrome in diverse populations from 12 countries. This study is the first to compare and contrast Down syndrome across diverse populations. It is the first in a series of studies to be used in the NIH’s Atlas of Human Malformation Syndromes in Diverse Populations, a free resource to help clinicians around the world diagnose birth defects and genetic diseases in people of diverse ancestry, and is the first in a series focused on different genetic syndromes.
Read more here.
Starting as a speck barely visible to the naked eye and ending the in utero phase of its journey at an average weight of 7.5 pounds, the growth of the human fetus is one of the most amazing events in biology. Of all the organs, the fetal brain undergoes one of the most rapid growth trajectories, expanding over 40 weeks from zero to 100 billion neurons — about as many brain cells as there are stars in the Milky Way Galaxy.
This exponential growth is part of what gives humans our unique abilities to use language or have abstract thoughts, among many other cognitive skills. It also leaves the brain extremely vulnerable should disruptions occur during fetal development. Any veering off the developmental plan can lead to a cascade of results that have long-lasting repercussions. For example, studies have shown that placental insufficiency, or the inability of the placenta to supply the fetus with oxygen and nutrients in utero, is associated with attention deficit hyperactivity disorder, autism, and schizophrenia.
Recent research has identified differences in the brains of people with these disorders compared with those without. Despite the almost certain start of these conditions within the womb, they have remained impossible to diagnose until children begin to show clinical symptoms. If only researchers could spot the beginnings of these problems early in development, says Children’s National Health System researcher Catherine Limperopoulos, Ph.D., they might someday be able to develop interventions that could turn the fetal brain back toward a healthy developmental trajectory.
“Conventional tools like ultrasound and magnetic resonance imaging (MRI) can identify structural brain abnormalities connected to these problems, but by the time these differences become apparent, the damage already has been done,” Limperopoulos says. “Our goal is to be able to pick up very early deviations from normal in the high-risk pregnancy before an injury to the fetus might become permanent.”
Before scientists can recognize abnormal, she adds, they first need to understand what normal looks like.
In a new study published in Cerebral Cortex, Limperopoulos and colleagues begin to tackle this question through the largest MRI study of normal fetal brains in the second and third trimesters of pregnancy. While other studies have attempted to track normal fetal brain growth, that research has not involved nearly as many subjects and typically relied on data collected when fetuses were referred for MRIs for a suspected problem. When the suspected abnormality was ruled out by the scan, these “quasi-controls” were considered “normal” — even though they may be at risk for problems later in life, Limperopoulos explains.
By contrast, the study she led recruited 166 healthy pregnant women from nearby low-risk obstetrics practices. Each woman had an unremarkable singleton pregnancy and ended up having a normal full-term delivery, with no evidence of problems affecting either the mother or fetus over the course of 40 weeks.
At least one time between 18 and 39 gestational weeks, the fetuses carried by these women underwent an MRI scan of their brains. The research team developed complex algorithms to account for movement (since neither the mothers nor their fetuses were sedated during scans) and to convert the two-dimensional images into three dimensions. They used the information from these scans to measure the increasing volumes of the cerebellum, an area of the brain connected to motor control and known to mediate cognitive skills; as well as regions of the cerebrum, the bulk of the brain, that is pivotal for movement, sensory processing, olfaction, language, and learning and memory.
Their results in uncomplicated, full-term pregnancies show that over 21 weeks in the second half of pregnancy, the cerebellum undergoes an astounding 34-fold increase in size. In the cerebrum, the fetal white matter, which connects various brain regions, grows 22-fold. The cortical gray matter, key to many of cerebrum’s functions, grows 21-fold. And the deep subcortical structures (thalamus and basal ganglia), important for relaying sensory information and coordination of movement and behavior, grow 10-fold. Additional examination showed that the left hemisphere has a larger volume than the right hemisphere early in development, but sizes of the left and right brain halves were equal by birth.
By developing similar datasets on high-risk pregnancies or births—for example, those in which fetuses are diagnosed with a problem in utero, mothers experience a significant health problem during pregnancy, babies are born prematurely, or fetuses have a sibling diagnosed with a health problem with genetic risk, such as autism—Limperopoulos says that researchers might be able to spot differences during gestation and post-natal development that lead to conditions such as schizophrenia, attention deficit hyperactivity disorder and autism spectrum disorder.
Eventually, researchers may be able to develop fixes so that babies grow up without life-long developmental issues.
“Understanding ‘normal’ is really opening up opportunities for us to begin to precisely pinpoint when things start to veer off track,” Limperopolous says. “Once we do that, opportunities that have been inaccessible will start to present themselves.”
Advanced noninvasive imaging permitted Children’s National Health System researchers to measure the lasting impact of abnormalities in blood flow on the immature brains of premature babies. Blood flow to the brain, or perfusion, has been studied previously to understand its role in other health conditions, but this is the first time a research team has mapped how these changes may contribute to brain injury suffered by babies born before 32 weeks’ gestation.
Preterm birth is a major risk factor for brain injury. The prospective study examined infants weighing less than 1,500 grams who were born prior to 32 gestational weeks.
Of 78 infants studied, 47 had structural brain injuries categorized as either mild or moderate to severe, and 31 had no brain injury. While global cerebral blood flow decreased with advancing postnatal age, the blood flow decreased more significantly among preterm infants with brain injury, says Eman S. Mahdi, M.D., M.B.Ch.B. Dr. Mahdi is a pediatric radiology fellow at Children’s National and lead author of the abstract.
“In addition to differences in global brain blood flow, we saw a marked decrease in regional blood flow to the thalamus and the pons, regions known to be metabolically active during this time,” Dr. Mahdi says. The thalamus helps to process information from the senses and relays it elsewhere within the brain. Located at the base of the brain, the pons is part of the central nervous system and also is a critical relay of information between the cerebrum and cerebellum. “These regional variations in blood flow reflect vulnerability of the cerebral-cerebellar circuitry,” she adds.
The Radiological Society of North America (RSNA) recognized Dr. Mahdi with its Trainee Research Prize. She presented the work, “Cerebral Perfusion Is Perturbed by Preterm Birth and Brain Injury,” during the RSNA Scientific Assembly and Annual Meeting, held from Nov. 27 to Dec. 2.
The findings point to the need for additional research to explore how cerebral blood flow trends evolve as preemies grow older and whether abnormal blood flow is linked to differences in health outcomes. In addition, the technique used by the research team, arterial spin labeling perfusion imaging – a type of magnetic resonance imaging – represents a useful and non-invasive technology for identifying early cerebral perfusion abnormalities in preterm infants, says Catherine Limperopoulos, Ph.D., director of the Developing Brain Research Laboratory at Children’s National and abstract senior author.
Premature birth can interrupt a key period of brain development that occurs in the third trimester, which has the potential to impact a child’s long-term learning, language, and social skills. A recent case-control study published in The Journal of Pediatrics applied diffusion tensor magnetic resonance imaging (DTI) to zoom in on the microstructures comprising the critical cerebellar neural networks related to learning and language, and found significant differences between preterm and full-term newborns.
“The third trimester, during which many premature births occur, is typically when the developing cerebellum undergoes its most dramatic period of growth. Normally, the cerebellar white matter tracts that connect to the deep nuclei are rich in pathways where nerve fibers cross. Those connections permit information to flow from one part of the brain to another. It is possible that premature birth leads to aberrant development of these critical neural networks,” says Catherine Limperopoulos, Ph.D., director of the Developing Brain Research Laboratory at Children’s National Health System and senior study author.
One in 10 American babies is born prematurely. The brain injury that infants born prematurely experience is associated with a range of neurodevelopmental disabilities, including some whose influence isn’t apparent until years later, when the children begin school. Nearly half of extremely preterm infants go on to experience long-term learning, social, and behavioral impairments.
While conventional magnetic resonance imaging (MRI) can detect many brain abnormalities in newborns, a newer technique called DTI can tease out even subtle injury to cerebral and cerebellar white matter that is not evident with conventional MRI. White matter contains axons, which are nerve fibers that transmit messages. With DTI, researchers can quantify brain tissue microstructure and describe the integrity of white matter.
The research team compared imaging from 73 premature infants born before 32 weeks gestation who weighed less than 1,500 grams with 73 healthy newborns born to mothers who delivered at full term after 37 weeks. After the newborns had been fed, swaddled, and fitted with double ear protection, the imaging was performed as they slept. Nurses monitored their heart rates and oxygen saturation. Their brain abnormalities were scored as normal, mild, moderate, or severe.
All of the full-term newborns had normal brain MRIs as did 44 (60.3 percent) of the preemies.
The preemies had significantly higher fractional anisotropy in the cerebellum, the part of the brain that processes incoming information from elsewhere in the brain, permitting coordinated movement as well as modulating learning, language, and social skills. Alterations in cerebellar microarchitecture was associated with markers for illness severe enough to require surgery – such as correcting abnormal blood flow caused by the failure of the ductus arteriosus to close after birth and to remedy a bowel disease known as necrotizing enterocolitis. The risk factors also are associated with compromised cardiorespiratory function and low Apgar score at five minutes, Limperopoulos and co-authors write. The Apgar score is a quick way to gauge, one minute after birth, how well the newborn withstood the rigors of childbirth. It is repeated at five minutes to describe how the newborn is faring outside of the womb.
“In previous studies, we and others have associated cerebellar structural injury in preterm infants with long-term motor, cognitive, and socio-affective impairments. This is one of the first studies to provide a detailed report about these unexpected alterations in cerebellar microstructural organization,” she adds. “We postulate that the combination of premature birth and early exposure of the immature developing cerebellum to the extrauterine environment results in disturbed micro-organization.”
Additional research is warranted in larger groups of patients as well as long-term follow up of this cohort of newborns to determine whether this microstructural disorganization predicts long-term social, behavioral, and learning impairments.
“A large number of these prematurely born newborns had MRI readings in the normal range. Yet, we know that these children are uniquely at risk for developing neurodevelopmental disabilities later in life. With additional study, we hope to identify interventions that could lower those risks,” Limperopoulos says.
Related resources: The Journal of Pediatrics editorial
Over the 22 years that Mary T. Donofrio, M.D., has been practicing fetal cardiology, the field has changed radically. The goal once had been simply to offer parents an accurate diagnosis and prepare them for sometimes devastating outcomes. Now, Dr. Donofrio, who directs the Fetal Heart Program and Critical Care Delivery Program at Children’s National Health System, says specialists can follow fetuses throughout the pregnancy and manage many conditions in the womb, greatly improving their chances of living long and productive lives.
Case in point: Transposition of the great arteries, a congenital defect characterized by reversal of the heart’s two main arteries—the aorta, which distributes oxygenated blood throughout the body, and the pulmonary artery, which carries deoxygenated blood from the heart to the lungs. The single abnormality means that the oxygenated “red” blood flows back to the lungs while deoxygenated “blue” blood flows out to the body.
After birth, when the cord is clamped and the connection to the placenta severed, the baby’s cardiovascular system must adjust. If the fetal connections between the two sides of the heart no longer remain, the brain and other organs in infants with this defect are severely deprived of oxygen. The condition may be fatal if something is not done immediately to reopen the fetal connections to stabilize the circulation before surgery can be done. But if the fetal cardiologist can keep tabs on what’s happening to the heart over time and prepare a specialty team of cardiologists to treat the problem immediately after birth, chances of survival are significantly improved.
More than a decade ago, as a young attending physician, Dr. Donofrio witnessed a case that has stuck with her to this day. The baby’s diagnosis of transposition of the great arteries was not made until shortly before birth. In addition, the two fetal blood flow connections that allow blood to circulate had closed, causing severe heart failure. Although the care team performed an emergency delivery and immediate cardiac procedure, including initiation of a heart-lung machine in the delivery room to try to stabilize the circulation, the baby ultimately died due to complications from a very low oxygen level. “I always wonder what happened,” Dr. Donofrio says. “Was the baby’s heart always that bad and nobody noticed it, or did it change over time?”
In a paper published recently in the Journal of Neonatal-Perinatal Medicine, she and colleagues illustrate the dramatic transformation in care that has taken place in the 14 years since this unforgettable case. The new publication describes the case of a different fetus diagnosed at 22 weeks gestation with transposition of the great arteries in 2015 at Children’s National. Unlike many congenital heart disorders, the heart’s four chambers appear misleadingly normal at the typical mid-pregnancy ultrasound. Despite the challenging diagnosis for many obstetricians, this fetus’ heart condition was recognized early by looking at the arteries leaving the heart in addition to the chambers.
While such a defect is fatal if left untreated, Dr. Donofrio explains there are two pathways that can allow the blood to get to where it needs to go such that the circulation is stabilized and the damage mitigated. One is the fetal blood vessel known as the ductus arteriosus that typically stays open for a day or two after birth. The second is an opening between the heart’s two upper chambers, known as the foramen ovale, which usually closes upon delivery. By keeping those two pathways open, blood can cross from one side of the heart to the other, buying time in the delivery room so that babies can be stabilized before they receive surgery to permanently move the arteries back to their normal position.
In the 2015 case, Dr. Donofrio and colleagues had the chance to monitor the fetus and the fetal heart at follow-up appointments every four weeks after diagnosis. What they saw completely changed the course of their treatment plan and likely saved the baby’s life. With each ultrasound, they saw that the ductus arteriosus and the foramen ovale—the critical connections needed for survival—were gradually closing.
Dr. Donofrio noted at the fetal evaluation at 38 weeks that the structures had closed, and the heart was showing signs that it was not functioning well. She and her team realized that the only way to save this baby was to deliver earlier than planned and to have cardiac specialists standing by ready to perform a life-saving procedure to open the connections right after the baby was separated from the placenta. The baby was delivered by Cesarean section in the cardiac operating room at Children’s. The cardiac intervention team immediately created a hole where the foramen ovale should have been by using a balloon to open the tissue that had closed. The care team also administered a prostaglandin infusion, a drug that can keep the ductus arteriosis open. This time, however, the medicine did not work. The baby was stabilized with several cardiac medications and, with little time to spare, the cardiac surgeons operated on the one-day-old baby to switch his great arteries back to the normal position, saving his life.
The baby is now 1-year-old, Dr. Donofrio says, and is healthy—a scenario that likely wouldn’t have happened had the fetal team not made the diagnosis and continually monitored the condition in the womb.
“I remember back to that first case when we were really scrambling to do everything we could at the last minute because we didn’t have the information we needed until the very end,” Dr. Donofrio says. “Now, we can spot problems early and do something about it. For me, that’s amazing. We’re making a difference, and that’s a really great thing.”
If it does not jeopardize the health of the pregnant mother or her fetus, pregnancies should be carried as close to full term as possible to avoid vulnerable preemies experiencing a delay in brain development, study results published October 28 in Pediatrics indicate.
Some 15 million infants around the world – and 1 in 10 American babies – are born prematurely. While researchers have known that preemies’ brain growth is disturbed when compared with infants born at full term, it remained unclear when preemies’ brain development begins to veer off course and how that impairment evolves over time, says Catherine Limperopoulos, Ph.D., Director of the Developing Brain Research Laboratory at Children’s National Health System and senior study author.
A look at the research
In order to shine a spotlight on this critical phase of fetal brain development, Limperopoulos and colleagues studied 75 preterm infants born prior to the 32th gestational week who weighed less than 1,500 grams who had no evidence of structural brain injury. These preemies were matched with 130 fetuses between 27 to 39 weeks gestational age.
The healthy fetal counterparts are part of a growing database that the Children’s National Developing Brain Research Laboratory has assembled. The research lab uses three-dimensional magnetic resonance imaging to carefully record week-by-week development of the normal in utero fetal brains as well as week-by-week characterizations of specific regions of the fetal brain.
The availability of time-lapsed images of normally developing brains offers a chance to reframe research questions in order to identify approaches to prevent injuries to the fetal brain, Limperopoulos says.
“Up until now, we have been focused on examining what is it about being born too early? What is it about those first few hours of life that leaves preemies more vulnerable to brain injury?” she says. “What is really unique about these study results is for the very first time we have an opportunity to better understand the ways in which we care for preemies throughout their hospitalization that optimize brain development and place more emphasis those activities.”
When the research team compared third-trimester brain volumes, preemies showed lower volumes in the cerebrum, cerebellum, brainstem, and intracranial cavity. The cerebrum is the largest part of the brain and controls speech, thoughts, emotions, learning, as well as muscle function. The cerebellum plays a role in learning and social-behavioral functions as well as complex motor functions; it also controls the balance needed to stand up and to walk. The brainstem is like a router, ferrying information between the brain, the cerebellum, and the spinal cord.
“What this study shows us is that every day and every week of in utero development is critical. If at all possible, we need to keep fetuses in utero to protect them from the hazards that can occur in the extra uterine environment,” she says.
In a small percentage of pregnancies, the fetuses’ hearts develop in the wrong place. In the congenital anomaly known as heterotaxy syndrome that often includes a severe heart defect, the heart is often displaced from its usual position in the left chest. In other instances, the heart starts out in a normal position; however, it is pushed out of its normal position by a mass that grows in the chest cavity, by abnormal development of the lungs, or due to other causes. Although rare, babies born with cardiac malpositions associated with other congenital defects can be the most serious of all possible birth defects.
Sometimes, fetuses with these congenital problems die in the womb. Others do not survive long after birth. In some pregnancies, surgery is performed shortly after childbirth to stabilize the circulation so newborns even have a chance at life.
Correctly diagnosing these cardiac conditions during pregnancy can help doctors and parents alike make the most informed decisions and plan ahead.
However, the tools now used most often to reveal the overall anatomic details of cardiac malpositions — obstetrical ultrasound and fetal echocardiography — often don’t give a full picture. A clear view of the fetus can be obscured by the position of the fetus, insufficient amniotic fluid, or even a mother’s body habitus. Imaging techniques sometimes also have a hard time distinguishing between liver, bowel, and lung because the echogenicity of these tissues — the signature that sound waves make as they bounce back from their targets — is so similar.
“To be able to offer parents the best and most comprehensive counseling, and to begin planning for the type of intensive and multidisciplinary care that many of these babies will require, we need to have access to as much information as we can about each baby, not only relating to the heart but all the other organs as well,” says Mary T. Donofrio, M.D., a pediatric cardiologist who directs the Children’s National Health System Fetal Heart Program and Critical Care Delivery Program. “Unfortunately in some instances, obstetrical ultrasound and fetal echocardiography, the two diagnostic tools used most often in these cases, can be limited in what they tell us.”
What fetal MRI can show
An underutilized technique that gathers more details about the associated abnormalities that often accompany cardiac malposition during pregnancy is fetal magnetic resonance imaging, or fetal MRI, says Dr. Donofrio. Even though this technique is widely used to diagnose other fetal conditions, such as brain anomalies, it’s rarely used to better define the overall anatomy in cardiac malposition.
To determine whether fetal MRI is effective in complementing obstetrical ultrasound and fetal echocardiography, the current standard of care for this condition, Dr. Donofrio and colleagues took a retrospective look at all cases of cardiac malposition in which fetuses were evaluated using MRI between 2008 to 2013 at Children’s National. Their search turned up 42 cases.
Twenty-three cases had been diagnosed with obstetrical ultrasound and fetal echocardiography as having additional abnormalities beyond the heart’s changed position, and 19 had been given the diagnosis of heterotaxy syndrome. Each patient had been assigned to various known subtypes of these conditions, with some classified as having an unknown etiology for the findings.
After fetal MRI, the diagnoses of nearly one-third changed or were better delineated. Seven of the 23 cases of cardiac malposition attributed to an extra cardiac anomaly were reassigned to a cause different from the original diagnosis based on the new, more detailed information provided by fetal MRI, including three in which a complete diagnosis could not be made due to poor visualization by ultrasound. Five of the 19 cases attributed of heterotaxy were reassigned to different subgroups within this disorder or were given a different diagnosis completely after fetal MRI.
In eight of these 12 diagnoses that changed after fetal MRI, doctors were able to confirm these findings postnatally. Other cases were either lost to follow-up, pregnancy termination, or fetal demise.
The research team led by Dr. Donofrio published these results in the August 2016 issue of Prenatal Diagnosis.
Overall, she says the findings demonstrated the benefits of using fetal MRI as an adjunct to obstetrical ultrasound and fetal echocardiography. MRI offers advantages over ultrasound, she explains, including better spatial resolution, a wider field of view, and a way to see through or around maternal body fat, overlying fetal bone, or a fetus whose position is not optimal.
“Determining the etiology of cardiac malposition remains a challenging diagnosis, and the value of accurate prenatal diagnosis has been long recognized,” Donofrio and colleagues write in the study. “Ultimately, fetal MRI can assist with identifying the etiology of cardiac malposition for informative prenatal counseling and multidisciplinary planning.”
Common, lifelong health conditions like diabetes and hypertension have footprints that can be traced back to the womb. With advanced fetal MRI we seek to understand as much as possible about brain development during the time in utero. Non-invasive imaging technology helps us to identify signs of abnormal fetal development that may facilitate earlier diagnoses of chronic conditions and intervention.
We’re exploiting both the power and safety of MRI to develop ways to pick up early signs and signals in fetuses whose brain development may be veering off in the wrong direction. Using this advanced technology we can begin to detect varying signals or other signs of distress. These signs of distress may appear in the form of a brain chemical imbalance or a structural brain abnormality that is too subtle to be seen by an ultrasound or other scan. We now have the ability to leverage magnetic resonance imaging to examine the brain in utero for even the most subtle derailments that can lead to lifelong consequences.
The first nine months of life, when a fetus is in the womb, is a time of unparalleled growth and a critical time for fetal brain development. As we examine the maturation of the fetal brain, we know that each and every cortical fold represents future function lost or gained and lays the fundamental background or platform from which critical functions will emerge such as language and social and behavioral development.
We are developing technology that can quickly and reliably pick up early signals of a fetal brain that’s going off route to provide the ability to access therapeutic windows that are currently inaccessible. Earlier identification and intervention can improve the quality of life for children and potentially could even reverse the abnormality.
Early identification of fetal distress is critical. To be able to provide an intervention you must first be able to know that a fetus is getting into trouble, and you must be able to identify the problem early enough, in order to intervene before it has already caused injury to the fetus.
About the Author
Catherine Limperopoulos, Ph.D.
Director, MRI Research of the Developing Brain; Director, Diagnostic Imaging and Radiology/Fetal and Transitional Medicine
Research interests: Fetal neonatal brain injury
Fetuses wiggle. They waggle. Some pirouette within the womb, amniotic fluid easing their spins. Pregnant mothers’ meals and beverages from hours earlier wend their way through their digestive systems. On top of that, mother and offspring may breathe out of sync and their hearts may beat in time to different drummers.
In short, there’s a whole lot of movement going on in the womb.
As anyone trying to capture a photograph with a digital camera knows, sudden movements are the enemy of a sharp image. The challenge is the same for fetal researchers aiming to capture crisp functional magnetic resonance imaging (fMRI) of the developing brains of fetuses who are always on the move.
Over two years, a Children’s National Health System research team led by Wonsang You, a research associate in the Developing Brain Research Laboratory, worked out complex mathematical algorithms to account for independent fetal and placental motions, to erase those noise artifacts, and to validate the accuracy of the technique.
“[M]otion correction is optimized to the experimental paradigm, and it is performed separately in each phase as well as in each region of interest (ROI), recognizing that each phase and organ experiences different types of motion. To obtain the averaged [blood oxygen level-dependent] BOLD signals for each ROI, both misaligned volumes and noisy voxels are automatically detected and excluded, and the missing data are then imputed by statistical estimation based on local polynomial smoothing,” You and colleagues wrote in a technical article published recently by the Journal of Medical Imaging and spotlighted on the journal’s website as a featured article.
To underscore the work’s clinical utility, they analyzed differences in fetal motion by acquiring BOLD fMRI data from eight pregnant women with healthy fetuses and comparing them with eight women whose fetuses had been diagnosed with congenital heart disease (CHD) between 25 to 40 weeks of gestational age. The team focused on changes in oxygenation of the fetal brain and placenta during maternal hyperoxia, an oxygen challenge test during which both groups of pregnant women received 100 percent oxygen via face mask for four to six minutes. Measurements were then taken to determine whether there were differences in how the fetuses and the placentas responded to the oxygen challenge test.
Recognizing compromised fetuses in utero – and understanding the subtle but important ways they deviate from the trajectory of normal fetuses – opens a critical window of opportunity to intervene through nutritional, pharmaceutical, or surgical means – before brain injury is consolidated, says Catherine Limperopoulos, PhD, Director, MRI Research of the Developing Brain at Children’s National, and the paper’s senior author.“
Our goal is to exploit the power of MRI, a non-invasive imaging technique, to detect the earliest signs of the fetus getting into trouble before it runs into serious problems,” Limperopoulos says. “We needed the technical development described in this foundational work to allow us to reliably measure the fMRI BOLD response in the fetal brain and placenta.”
The BOLD signal can be degraded by the independent and collective movements of the mother and fetus. Traditional motion correction makes assumptions, such as treating all moving objects like the fetal brain, which is solid, rigid, and has a high range of motion. The traditional approach also fails to account for such subtleties as the placenta’s low range of motion and its flexing in response to maternal and fetal movements.
The research team employed four-step pre-processing – which included correcting bias magnetic field, correcting for global and local motion, and rejecting outliers – and followed with data imputation, an alphabet soup of letters and Latin symbols that mathematically accounts for objects (placenta and fetal brain) that move independently.“
We showed that the proposed preprocessing pipeline can be effectively employed to characterize fetal motion in healthy controls and CHD fetuses. Our preliminary data suggest that the degree of fetal motion tends to increase during hyperoxia in CHD fetuses (but not significantly). In addition, the motion of the fetal brain in CHD cases showed higher variance during hyperoxia compare[d] to controls,” You and colleagues write. “These observations suggest that the CHD fetus may be more responsive to maternal hyperoxia. However, these pilot data need to be validated on a larger cohort of healthy and high-risk CHD fetuses.”
Related resources: Research at a Glance
Questions for Future Research
Source: “Impaired Global and Tissue-Specific Brain Development in the Growth-Restricted Fetus.” N. Andescavage, J. Cruz, M. Metzler, A. du Plessis, and C. Limperopoulos. Presented during the 2016 Pediatric Academic Societies Annual Meeting, Baltimore, MD. May 2, 2016.
The brain of the 21-week-old aborted fetus weighed only 30 grams. Zika RNA, viral particles, and infectious virus were detected, and Zika virus isolated from the fetal brain remained infectious when tested. The concentration of virus was highest in the fetal brain, umbilical cord, and placenta. The mother remained infected with Zika virus at 21 weeks, some 10 weeks after her initial infection.
Questions for Future Research
Source: “Zika Virus Infection with Prolonged Maternal Viremia and Fetal Brain Abnormalities.” R.W. Driggers, C.Y. Ho, E.M. Korhonen, S. Kuivanen, A.J. Jääskeläinen, T. Smura, D.A. Hill, R. DeBiasi, G. Vezina, J. Timofeev, F.J. Rodriguez, L. Levanov, J. Razak, P. Iyengar, A. Hennenfent, R. Kennedy, R. Lanciotti, A. du Plessis, and O. Vapalahti. The New England Journal of Medicine. June 2, 2016.
Federal health officials continue to investigate the first possible cases of domestic Zika virus transmission in Florida. In light of the growing number of Zika infections, the vast majority of which have been associated with foreign travel, vigilance for additional cases is warranted – particularly as summer heat intensifies and mosquito populations grow. The Centers for Disease Control and Prevention (CDC) now advises that all pregnant women in the continental United States and U.S. territories be evaluated for Zika infection at each prenatal care visit. The CDC also recognizes that Zika-exposed infants will require long-term, multidisciplinary care.
In mid-May, Children’s National Health System Fetal Medicine Institute and Division of Pediatric Infectious Disease announced the formation of a Congenital Zika Virus Program to serve as a dedicated resource for referring clinicians and for pregnant women to receive counseling and science-driven answers about the impact of the Zika virus on pregnancies and newborns. Children’s clinicians have consulted on 30 pregnancies or births with potential Zika virus exposure and/or infection. As of Aug. 31, eight were Zika-positive or probable. One of the pregnancies was the subject of an article published by The New England Journal of Medicine.
”While we’re hopeful there are few local cases, the Congenital Zika Virus Program has been developing emergency response plans in collaboration with local departments of health to prepare for any eventuality,” says Roberta DeBiasi, MD, MS, Chief of the Division of Infectious Disease and Congenital Zika Virus Program co-leader.
Over the years, Children’s National has invested in equipment and highly trained personnel, building world-class expertise in infectious diseases, pediatric neurology, pediatric cardiology, genetics, neurodevelopment, and other specialties. Children’s clinicians are recognized leaders in next-generation imaging techniques, such as fetal MRI, which detects more subtle and earlier indications of impaired brain growth. A variety of divisions work together to offer multidisciplinary support and coordinated care to infants born with special needs. As the nation braces for the possible expansion of Zika virus infection to other states, Children’s National is facilitating the multi-step process of testing blood, urine, and tissue with state health departments, helping to ensure timely and precise information. Children’s National specialists guide Zika-affected pregnancies through the fetal period and are able to oversee and coordinate the care of Zika-affected infants after delivery. Care and clinical support is provided by a multidisciplinary team of pediatric neurologists, ophthalmologists, audiologists, physical and occupational therapists, infectious disease experts, and neurodevelopmental physicians.
The Children’s National multidisciplinary team includes:
- Adre du Plessis, M.B.Ch.B., Director of the Fetal Medicine Institute, Chief of the Fetal and Transitional Medicine Division, and Congenital Zika Virus Program co-leader;
- Roberta DeBiasi, M.D., M.S., Chief of the Division of Infectious Disease and Congenital Zika Virus Program co-leader;
- Cara Biddle, M.D., M.P.H., Medical Director, Children’s Health Center, and a bilingual expert on complex care;
- Dorothy Bulas, M.D., Radiologist in the Division of Diagnostic Imaging and Radiology;
- Taeun Chang, M.D., Director, Neonatal Neurology Program in the Division of Neurophysiology, Epilepsy and Critical Care Neurology;
- Sarah Mulkey, M.D., Ph.D., Fetal-Neonatal Neurologist, Fetal Medicine Institute;
- Lindsay Pesacreta, M.S., F.N.P.-B.C., Board-Certified Family Nurse Practitioner; and
- Gilbert Vezina, M.D., attending Radiologist in the Division of Diagnostic Imaging and Radiology and Director of the Neuroradiology Program.
Each week, as temperatures rise, the likelihood increases that the United States will experience domestic Zika virus transmission. Indeed, such domestic Zika transmission already is occurring in Puerto Rico and the U.S. Virgin Islands. The Children’s National Health System Fetal Medicine Institute and Division of Pediatric Infectious Disease announced the formation of a Congenital Zika Virus Program to serve as a dedicated resource for referring clinicians and for pregnant women to receive counseling and science-driven answers about the impact of the Zika virus on their pregnancies.
Over years, Children’s National has invested in equipment and highly trained personnel, building expertise in infectious diseases, pediatric neurology, pediatric cardiology, genetics, neurodevelopment, and other specialties. Children’s clinicians are recognized as national leaders in next-generation imaging techniques, such as fetal MRI, and a variety of divisions work together to offer multidisciplinary support and coordinated care to infants born with special needs. As the nation prepares for the Zika virus, Children’s National is facilitating the multi-step process of blood testing, helping to ensure timely and precise information. Children’s National specialists are able to guide Zika-affected pregnancies through the fetal period and can oversee the care of Zika-affected infants after delivery. Care and clinical support is provided by a multidisciplinary team of pediatric neurologists, physical therapists, infectious disease experts, and neurodevelopmental physicians.
While many infants with mild disease require no intervention, others have complex CHD that necessitates specialized treatment shortly after birth. Complex defects change how blood ﬂows through the heart and to other organs—including the brain.
Questions for Future Research
Source: “Functional Brain Connectivity Is Altered in Fetuses With Congenital Heart Disease.” J. De Asis-Cruz, A. Yarish, M. Donofrio, G. Vezina, A. du Plessis, and C. Limperopoulos. Presented during the 2016 American Society of Neuroradiology Annual Meeting, Washington, DC. May 25 2016.
A team of researchers used 3-D volumetric magnetic resonance imaging (MRI) in an innovative study that reported that when the placenta fails to grow adequately in a fetus with congenital heart disease (CHD), it contributes to impaired fetal growth and premature birth. Fetal CHD involves an abnormality of the heart and is associated with increased risk for neurodevelopmental morbidity.Until now, CHD in the fetus and its relationship to placental function has been unknown. But the advanced fetal imaging study has shown for the first time that abnormal growth in the fetus with CHD relates to impaired placental growth over the third trimester of pregnancy. Catherine Limperopoulos, PhD, Director of Children’s National Developing Brain Research Laboratory in the Division of Diagnostic Imaging and Radiology, is the senior author of the study published in the September 2015 issue of the journal Placenta, “3-D Volumetric MRI Evaluation of the Placenta in Fetuses With Complex Heart Disease.”
Specifically, the decreased 3-D volumetric MRI measurements of pregnant women reported in this study suggest placental insufficiency related to CHD. The placenta nourishes and maintains the fetus, through the delivery of food and oxygen. Its volume and weight can determine fetal growth and birth weight.
Abnormality in placental development may contribute to significant morbidity in this high risk-population. This study shows impaired placental growth in CHD fetuses is associated with the length of the pregnancy and weight at birth. Nearly 1 in every 100 babies is born in the United States with a congenital heart defect.
Developing the capacity to examine the placenta non-invasively using advanced MRI is needed to identify early markers of impaired placental structure and function in the high-risk pregnancy. This is a critical first step towards developing strategies for improved fetal monitoring and management, Dr. Limperopoulos says.
“We are trying to develop the earliest and most reliable indicators of placental health and disease in high-risk pregnancies. Our goal is to bring these early biomarkers into clinical practice and improve our ability to identify placental dysfunction,” Dr. Limperopoulos says. “If we can develop the capacity to reliably identify when things begin to veer off course, we then have a window of opportunity to develop therapies to restore function.”
The study used in-vivo 3-D MRI studies and explored placental development and its relationship to neonatal outcomes by comparing placental volumetric growth in healthy pregnancies and pregnancies complicated by CHD.
While mortality rates continue to decrease steadily in newborns diagnosed with complex CHD, long-term neurodevelopmental impairments are recognized with increasing frequency in surviving infants, Dr. Limperopoulos says.
“Our goal is to better support the developing fetus with CHD. We can best accomplish this if we develop technology that can allow us to safely and effectively monitor the fetal-placental unit as a whole throughout pregnancy,” Dr. Limperopoulos says.
“This is the new frontier, not only to ensure survival but to safeguard the fetus and to ensure the best possible quality of life,” she says.
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