Transverse relaxation time (T2*) mapping of placental oxygenation is associated with fetal brain volumes, according to a recent study published in JAMA Network Open.
Takeaways
- Transverse relaxation time (T2*) mapping of placental oxygenation shows a correlation with fetal brain volumes, suggesting a potential link between placental function and brain development.
- Placental dysfunction, particularly in severe cases leading to intrauterine growth restriction (IUGR), affects nutrient and oxygen transfer to the fetus, impacting fetal development, especially during critical gestational periods.
- Infants with IUGR exhibit brain sparing phenomenon, where blood flow prioritizes the brain over other organs, potentially affecting higher-order brain functions due to reduced oxygenation in cortical regions.
- T2* mapping, which is associated with MRI-based measures of placental oxygenation, could serve as a sensitive indicator of fetal brain development, offering insights into the impact of placental function on brain growth.
- The study utilized MRI scans and linear mixed-effects analysis to assess the relationship between placental T2* values and fetal brain volumes. Results showed dissociation between T2* values and cortical versus subcortical brain regions, indicating the potential of T2* mapping as a biomarker for fetal hypoxia and brain development.
Placental dysfunction has been linked to decreased nutrient and oxygen transfer to the fetus, with outcome severity impacted by the gestational age during which placental dysfunction occurs. Data has indicated hierarchical blood flow distribution among fetuses with severe placental dysfunction leading to intrauterine growth restriction (IUGR).
Infants with IUGR experience brain sparing, where oxygenated blood is directed away from fetal organs and toward the brain. Data has indicated increased blood flow in subcortical regions critical for homeostasis. However, this takes blood from cortical regions responsible for higher-order functions.
More sensitive techniques are necessary to determine how placental function impacts the brain. As T2* has been associated with a magnetic resonance imaging (MRI)–based measure of placental oxygenation and birth weight, it may be utilized as a potential indicator of fetal brain development.
Investigators conducted a prospective cohort study to evaluate the efficacy of placental MRI-based methods as a biomarker of fetal brain development. Participants included female patients recruited between December 2020 and August 2023.
Patients underwent an MRI scan 2 times separated by over 2 weeks during the third trimester. A 3T GE Discovery MRI scanner and 32-channel torso coil were utilized to obtain 2D multiecho stack placental and single-shot fast spin echo anatomical brain images, while FSLeyes version 1.6.1 (FMRIB Centre) was used to draw placental masks.
T2* values, standardized based on gestational age, were measured by fitting the mean signal of a mask as a function of echo time. Linear mixed-effects (LME) analysis was performed for cortical and subcortical volumes as an interaction between T2* values and region. Covariates included maternal age, fetal sex, time point, and socioeconomical status.
There were 87 scans performed, with 49 participants undergoing an initial scan and 38 having available second time point data. A negative correlation was reported between placental T2* values and gestational age, while a positive correlation was reported between volumes and gestational age.
A significant interaction was observed between T2* and region during the LME analysis. A larger slope was measured in cortical regions vs subcortical regions. Besides the impact of the time point, no other significant associations were found.
These results indicated dissociation between T2* and cortical vs subcortical brain regions. Investigators concluded T2* can be used to measure placental function and fetal hypoxia and as a biomarker for fetal brain development.
Reference
Nichols ES, Al-Saoud S, de Vrijer B, et al. T2* Mapping of placental oxygenation to estimate fetal cortical and subcortical maturation. JAMA Netw Open. 2024;7(2):e240456. doi:10.1001/jamanetworkopen.2024.0456
