Thursday, 28 March, 2024
HomeObstetricsMRI technique spots placental problems in foetuses in early weeks – US...

MRI technique spots placental problems in foetuses in early weeks – US study

A new MRI imaging technique to assess placenta health in developing foetuses in early pregnancy has been developed that can reliably predict development complications and pregnancy risks from as early as 10 weeks. It can also be adapted to most MRI scanners, and used to screen placental health.

Foetal growth and blood flow are currently monitored by ultrasound. However, it is limited in predicting long-term comorbidity.

Atypical development of the placenta can be linked to many adverse outcomes, including abnormal foetal growth, pre-eclampsia, pre-term labour and stillbirth, reports Medical News Today (MNT).

“This new methodology provides an additional tool that healthcare providers can use to assess placental vascular function,” said Victoria Roberts, PhD, research assistant professor in the Division of Developmental and Reproductive Sciences at the Oregon National Primate Research Centre, one of the study’s authors.

“Being able to detect a placenta-related problem early in pregnancy can create a more targeted approach to clinical management, allowing clinicians to provide better treatment options to mothers and developing babies.”

The study was published in the journal PLOS ONE.

The researchers monitored 316 pregnancies between weeks 11 and 38 of gestation for the study. Of those, 62.6% were considered “low risk”, while the remaining 37.4% were considered at a high risk of complications, including: low birth weight, stillbirth, foetal deaths/anomalies and preterm birth.

Expectant people underwent MRI scans up to three times to detect a signal in the blood linked to oxygen availability and placental blood flow known as T2*.

To test the validity of T2* metrics under different environmental conditions, the researchers recruited participants from Oregon Health and Science University (OHSU), at an altitude of 450 feet above sea level, and the University of Utah, 4.840 feet above sea level.

After analysing the data, they found that T2* levels were significantly lower in the high risk pregnancy group than in the low risk pregnancy group from 15-33 weeks of pregnancy.

They further found that T2* readings from as early as 10-20 weeks of gestation could potentially identify at-risk pregnancies. The findings were similar both in Oregon and Utah, meaning the method could be used in different environmental settings.

They added, however, that small differences in the predictive power of T2* readings between the sites mean they should be based on altitude-specific norms.

The new technique could be easily implemented on practically all modern MRI scanners and thus may be easily adapted to assess placental function in prenatal care settings, they said.

Positive results, but research may be limited

The study authors noted that their results might be limited as they included a small number of adverse outcomes. They also noted that as participants included in their study were mostly of the same ethnicity and race, their findings might not apply to other demographics.

Dr Angela Martin, medical director of labour and delivery at the University of Kansas Medical Centre, who not involved in the study, told MNT:

“This is an interesting article describing a potential new tool that could be useful for predicting adverse outcomes in the future. However, at this time, it is unclear if T2* BOLD-MRI is a better screening tool than using risk factors, medical history, and ultrasound to screen for adverse pregnancy outcomes.”

Implications for placenta repair

Dr Thomas Ruiz, OB/GYN lead at Memorial Care Orange Coast Medical Centre in Fountain Valley, California, who was not involved in the study, said repairing the placenta was not yet possible.

When asked which interventions might nevertheless protect the developing foetus and its carrier, he told MNT:

“At this point, our interventions are somewhat limited (to) patients with pre-existing hypertension, a high risk for developing preeclampsia, a previous history of an infant born with intrauterine growth retardation, or a history of previous stillbirth. We start those patients on daily baby aspirin starting at 13 weeks of pregnancy. These high risk patients also have an ultrasound for growth every three to four weeks starting at 20 weeks gestation.”

“Antepartum testing can start as early as 32 weeks gestation, which incorporates a non-stress test and a measurement of fluid around the baby. Some of these patients will also undergo weekly flow studies of the umbilical cord. We will also put a certain percentage of these patients on bed rest, and so they spend most of their day lying on their left side. Lying on the left side increases placental perfusion.”

He added that people with pre-existing hypertension or who develop gestational hypertension are usually put on anti-hypertensive medications.

“If the patient is at high risk of early delivery before 37 weeks, we give the mother a course of antenatal steroids to speed up pulmonary maturity in the foetus.”

Study details

Quantitative longitudinal T2* mapping for assessing placental function and association with adverse pregnancy outcomes across gestation

Matthias Schabel, Victoria Roberts, Karen Gibbins , Monica Rincon, Jessica Gaffney, Aaron Streblow, Adam Wright, Jamie Lo, Byung Park, Christopher Kroenke, Kathryn Szczotka, Nathan Blue, Jessica Page, Antonio Frias, et al.

Published in PLOS ONE on 19 July 2022

Abstract
Existing methods for evaluating in vivo placental function fail to reliably detect pregnancies at-risk for adverse outcomes prior to maternal and/or foetal morbidity. Here we report the results of a prospective dual-site longitudinal clinical study of quantitative placental T2* as measured by blood oxygen-level dependent magnetic resonance imaging (BOLD-MRI). The objectives of this study were: 1) to quantify placental T2* at multiple time points across gestation, and its consistency across sites, and 2) to investigate the association between placental T2* and adverse outcomes. 797 successful imaging studies, at up to three time points between 11 and 38 weeks of gestation, were completed in 316 pregnancies. Outcomes were stratified into three groups: (UN) uncomplicated/normal pregnancy, (PA) primary adverse pregnancy, which included hypertensive disorders of pregnancy, birthweight <5th percentile, and/or stillbirth or foetal death, and (SA) secondary abnormal pregnancy, which included abnormal prenatal conditions not included in the PA group such as spontaneous preterm birth or foetal anomalies. Of the 316 pregnancies, 198 (62.6%) were UN, 70 (22.2%) PA, and 48 (15.2%) SA outcomes. We found that the evolution of placental T2* across gestation was well described by a sigmoid model, with T2* decreasing continuously from a high plateau level early in gestation, through an inflection point around 30 weeks, and finally approaching a second, lower plateau in late gestation. Model regression revealed significantly lower T2* in the PA group than in UN pregnancies starting at 15 weeks and continuing through 33 weeks. T2* percentiles were computed for individual scans relative to UN group regression, and z-scores and receiver operating characteristic (ROC) curves calculated for association of T2* with pregnancy outcome. Overall, differences between UN and PA groups were statistically significant across gestation, with large effect sizes in mid- and late- pregnancy. The area under the curve (AUC) for placental T2* percentile and PA pregnancy outcome was 0.71, with the strongest predictive power (AUC of 0.76) at the mid-gestation time period (20–30 weeks). Our data demonstrate that placental T2* measurements are strongly associated with pregnancy outcomes often attributed to placental insufficiency.

 

MedicalNews Today article – New MRI imaging detects pregnancy complications as early as 10 weeks (Open access)

 

PLOS ONE article – Quantitative longitudinal T2* mapping for assessing placental function and association with adverse pregnancy outcomes across gestation (Open access)

 

See more from MedicalBrief archives:

 

Hand-held ultrasound scanner shows its potential in rural Africa

 

RNA molecules in maternal blood may predict pregnancies at risk for pre-eclampsia

 

MRI superior to echocardiography in heart failure diagnosis – UK study

 

Extensive placental damage in some unvaccinated women causes stillbirths

 

 

 

MedicalBrief — our free weekly e-newsletter

We'd appreciate as much information as possible, however only an email address is required.