How Can MRIs Advance Understanding of Placenta Health

September 26, 2022 - In a recent publication in Plos One, researchers from Oregon Health and Science University (OHSU) shared data on a study using MRIs to assess placenta health. LifeScienceIntelligence interviewed Victoria Roberts, PhD, a research associate professor at OHSU and coauthor of the study, to discuss how MRIs can advance the understanding of placenta health and facilitate improved care in obstetrics and gynecology (OB/GYN) practices.

Project Overview

To start, Roberts gave LifeScienceIntelligence an overview of the project’s scope. She explained that the study first began at the Oregon National Primate Research Center and occurred on non-human primates.

Non-Human Primates

“The other researchers and I used non-human primate models to understand the placenta and pregnancy. We've developed technology and methodologies using the non-human primate that we've been able to apply, translate, and move forward within the human,” Roberts remarked.

She noted that when looking at the placenta, researchers and clinicians are looking at two different circulations: the pregnant person and the baby. A healthy pregnancy is marked by adequate nutrient-dense blood flow from the pregnant person to the baby.

“One of the challenges providers have in terms of technology and methods to looking at this is how to access both sides, see things differently, and distinguish between the two,” asserted Roberts. “A contrast agent helps visualize the blood flow on the mother’s side of the placenta. Contrasts agents can help clinicians see what is going on; however, they don't want to do that in pregnant women.”

To address this issue, researchers in this study first began to study placenta health in non-human primates. According to Roberts, they developed a non-contrast method using contrast agents. She explained that creating the methodology in non-human primates allowed them to implement it in humans.

Human Trials

“The other researchers and I enrolled pregnant individuals to take part in three MRIs: toward the end of the first trimester, mid-pregnancy, and then in the third trimester. Then we could track what blood flow to the placenta looks like in these uncomplicated pregnancies,” shared Roberts.

After understanding what a healthy blood flow looks like, Roberts and her colleagues recruited patients with higher-risk pregnancies. “We had this well-characterized group of over 300 women who had three MRIs each. From their placenta and notes, we could see the pregnancy outcome,” she continued.

The Importance of Placenta Health

Beyond explaining the research, Roberts expanded on the importance of placenta health and the current limitations of assessing placenta health in obstetrics.

“To give a bit more context, back in 2014, the NIH recognized that the placenta was a key and important organ that wasn't very well understood considering its important role. Researchers now know that pregnancy is just setting up that offspring for life. Those nine months in utero are programming many aspects that'll impact the child later,” revealed Roberts.

Currently, there are some limitations in understanding placenta health. “Ultrasound does have the ability to detect abnormalities, but often they're more severe by the time an ultrasound can detect it, or it's further down in pregnancy in terms of the time,” she explained. “In theory, using MRI is giving an additional diagnostic tool that can be implemented where there's cause for concern.”

Technology Limitations

Despite the potential benefits of this technology, Roberts anticipates that the technology will not be widely used for multiple reasons.

“The machines themselves aren't that widely available compared to an ultrasound, which is often in a clinic or outpatient setting,” she began.

Cost of MRI 

In addition to limited availability, MRI machines are expensive, and the technology itself becomes costly for providers and patients. “MRI is pricey, it is an expensive methodology, but where warranted, it is valuable,” stated Roberts.

According to Heartland Imaging, MRI machines cost a minimum of $150,000 in the United States. The average cost ranges between $1 million and $3 million, and those costs do not include installation or necessary precautions. Also contributing to the lack of availability are machine and upkeep prices.

Time and Comfort

Roberts also mentioned that MRIs are time-consuming, especially those looking at every slice. The pregnant individual must remain in the machine for an extended period. While this may not be a concern for some, others may struggle with claustrophobia or overstimulation from the machine’s noise.

Future Directions

This research has been a significant advancement in obstetrics, imaging, and placenta health. Yet, the study conducted had some limitations. LifeScienceIntelligence asked Roberts about the next steps for this technology and research.

Additional Study Populations

First, she suggested additional population studies. “Thinking about demographics, this study didn’t have a diverse population. Normal placenta health may be different in other populations of individuals or different ethnicities. Again, the study is still one step removed in some ways. Researchers need to do studies that specifically address that piece of it and establish what’s normal elsewhere,” she noted.

This is an important area for additional research as maternal and fetal health can vary drastically based on race and ethnicity. According to the CDC, the maternal mortality rate for Black women is nearly three times that of White women.

Additional Study Methods

On top of studying other populations, Roberts explained that her team hopes to test how different scanning techniques would work. She told LifeScienceIntelligence that they are currently looking at every slice of the MRI to gather a picture of the placenta’s health. In addition to looking at each slice, the team also looked at every other slice.

Future research will hopefully determine how many slices can be skipped to maintain sensitivity. “Part of that process is making it more accessible and reducing the time — which would reduce the cost and increase the comfort level for patients,” she reasoned.  

Data Analysis

While this study worked out a lot of the technology, data analysis has some limitations. The first complexity comes with extracting the images of the placenta.

“In this study, the image is of the entire uterus, and the placenta and the baby are within that. To extract this data, somebody had to delineate, i.e., draw around, the placenta in all those slices. It was a big undertaking for a couple of people,” remarked Roberts.

She went on to explain how this is not clinically accessible. While taking every other slice reduces the workload by 50%, there is still a significant amount of time that must go into isolating the placenta before any actual analysis can be conducted.

LifeScienceIntelligence asked what the data analysis looks like once the placenta has been isolated. She shared that “at this point, it's experimental in terms of it being researched because there's a lot of analysis and post-processing. There's the scan itself which acquires, but then to process the data, quite a bit of work goes in.”

Currently, the data is being analyzed in depth by a research team. Still, Roberts explains that the current data analytics would be difficult and time-consuming to implement in a clinical setting. She mentions that an additional research point would be to advance and streamline the analysis of the MRI scans.

“It's definitely going to have to be something pretty intuitive, and a machine can drive it basically,” she mused. “The next step must be looking at the data analysis piece. How can that be streamlined? What can be done through machines? What could be automated?”

As this research continues to progress, evolve, and advance, it may provide an additional tool for obstetricians to determine placenta health early in pregnancy. Doctors and other healthcare professionals may be able to give those carrying children a more well-rounded picture of their pregnancy. The hope is that this technology — once fine-tuned and FDA approved — could facilitate early intervention and reduce the rates of maternal and fetal mortality.