How Advancing Fetal Cardiac MRI Capabilities is Improving Care

How are doctors pushing the limits of technology to more accurately diagnose fetal heart conditions?

Imaging the heart of a fetus is innately tricky, requiring precision and expertise. MRI has the potential to provide critical diagnostic information in fetal heart conditions in addition to standard imaging options, but that’s because the small size of the heart in utero, the fast heartbeat and the normal movement of the baby can make clear images difficult to capture. Clear fetal heart images are crucial to providing families with an accurate diagnosis and a detailed plan for postdelivery care. Over the past several years, the fetal cardiac MRI team at Children’s Hospital Colorado has been exploring new technology to find a solution to these challenges and finally achieve a clear, crisp movie of the beating fetal heart, thanks to a special clinician-scientist partnership.

Bringing the images to life required a collaboration between Alex Barker, PhD, Erin Englund, PhD, and cardiac experts Lorna Browne, MD, and Richard Friesen, MD. Since 2019, the team has been working with industry partners on an MRI-compatible Doppler ultrasound device which uses ultrasound to detect fetal heartbeat and transmit this signal to the MRI scanner. Those images are then synchronized to the fetal heartbeat, creating depictions of the moving heart and allowing the team to see complex fetal cardiovascular conditions in exquisite detail. With U.S. Food and Drug Administration approval of this new Doppler ultrasound gating device, the team is working on clinical translation of these methods for accurately diagnosing congenital heart disease and other cardiovascular abnormalities prenatally.

“We are pushing the boundaries of our technology on all fronts,” Dr. Barker says.

Focusing on function and flow

As this technology is so novel, there was a need to establish normative data on fetal structures, including ventricle sizes and ventricular function, to reliably detect subtle abnormalities. In 2024, the team published the first normative data on fetal heart dimensions and fetal heart function using fetal cardiac MRI (1). This work provides a baseline reference for implementing this new technology into practice.

But the team did not stop there. They wanted to see more than just the size of the fetal heart structures to be able to gather the most detailed information possible about congenital heart diseases. They also hoped to be able to visualize and quantify the distribution of blood flow throughout the fetal circulation. To do this, they needed to find a way to use a technique called 4D flow MRI in the fetus. This technique is a type of MRI that allows doctors to see 3D, time-resolved images of the heart and to measure 3D blood flow through the entire cardiovascular system. Dr. Barker was part of the first team to do 4D flow on adult hearts, and over the last 8 years, he and his team developed faster sequences to apply this first to small children, and then most recently, to fetuses — where it is revolutionizing how doctors view fetal cardiovascular conditions.

Because it had never been done before in a fetus, the team again needed to establish normative values for fetal blood flow distribution. Dr. Englund, along with postdoctoral research fellow Takashi Fujiwara, PhD, spearheaded the team’s most recent publication where researchers applied fetal 4D flow MRI to healthy pregnant patients to quantify the normative distribution of fetal blood flow by 4D flow MRI (2).

“Reliable normative data is an essential step to widespread clinical application,” Dr. Browne explains. “In particular, mapping the normal distribution of blood flow in the fetus with fetal 4D flow is a hugely important step because now we can look at the flow distribution in our patients and make better informed diagnoses.”

Dr. Englund adds, “It’s so rewarding to be a part of this team and to have all the infrastructure in place to be able to make such a huge difference. We’ll continue to grow and push the envelope with others jumping on board with us. There’s a lot of potential for the future of this.”

With a quick research pipeline from idea conception to implementation of new technology, the Colorado Fetal Care Center at Children’s Colorado is now the only center in the U.S. routinely performing 4D flow for prenatal patients, and the fetal cardiac MRI team continues to push the boundaries of this technology. The team is now working on even more exciting developments using artificial intelligence and motion correction with international collaborators.

“I’ve worked on lots of projects over my career as a scientist. I’ve never been this close to translation so quickly,” Dr. Barker says. “It’s pretty exciting to be able to take something that we’ve been working on in the lab and see it actually making an impact. That’s what motivates me every day here. It’s not just a hypothetical.”

Boosting diagnostic accuracy

The main area in which the team is seeing a major impact is diagnosing coarctation of the aorta (CoA), a congenital heart defect that occurs when a baby’s aorta doesn’t form properly during pregnancy. Current standard technology has limitations when it comes to diagnosing this complex condition, resulting in about a 50% false positive rate, despite best efforts. These false positives have significant implications for families, from impacting maternal mental health and finances, to increasing time spent in the hospital postpartum while teams work to confirm a diagnosis.

“Every modality has its limitations,” Dr. Browne says. “When you have these difficult cases where echocardiograms can’t be definitive, MRI provides an additional modality and an opportunity to be definitive. That really impacts the counseling of patients and delivery planning.”

Providing families with an accurate diagnosis during pregnancy for conditions like CoA allows patients the chance to have clear expectations. Patients who faced the possibility of a CoA diagnosis and now can accurately find out their baby does not have the condition, get to deliver at their home hospital with their own care team and bond with baby immediately after delivery. Before this technology, they would have remained unsure if their baby would have this condition until medical interventions and testing after birth.

“This is supposed to be a very exciting time in pregnancy, and then families might get the news that their child has this heart condition, and the excitement turns to anxiety,” Dr. Barker says. “Knowing that for one out of every two patients we might be reducing that anxiety motivates me.”

And for families with an accurate confirmed CoA diagnosis during pregnancy, the team can make a detailed plan for care postdelivery.

“For some patients it’s hard news, but at the same time they are so grateful that we are able to tell them this information, and they know exactly what is going to happen,” Dr. Browne says.

Striving for more

The team is onboarding other hospitals across the country to the new Doppler ultrasound gating device and helping them launch similar programs. While they are training others to join in these efforts, they are also focusing on other conditions that could benefit from this type of technology.

“It has a really wide scope of potential applications,” Dr. Browne says. “What we’re focusing on currently are the conditions where fetal cardiac MRI can make a dramatic difference to patient care such as informing interventions by improving delivery room and postnatal care planning and hopefully improving patient outcomes. It’s exciting to be part of such a great team doing such important work.”

Citations

1. Minocha, Prashant K et al. “Reference Values for Reference Values for Fetal Cardiac Dimensions, Volumes, Ventricular Function and Left Ventricular Longitudinal Strain Using Doppler Ultrasound Gated Cardiac Magnetic Resonance Imaging in Healthy Third Trimester Fetuses.” Journal of magnetic resonance imaging : JMRI vol. 60,1 (2024): 365-374. doi:10.1002/jmri.29077. 
2. Englund, Erin K et al. “Reliability of 4D Flow MRI for Investigation of Fetal Cardiovascular Hemodynamics in the Third Trimester.” Radiology. Cardiothoracic imaging vol. 6,6 (2024): e240119. doi:10.1148/ryct.240119.