A non-invasive magnetic resonance imaging (MRI) technique is demonstrating promise in identifying fetal congenital heart disease (CHD) before birth, according to research published this week in Magnetic Resonance in Medicine. The method focuses on measuring placental vascular reactivity (PLVR), the placenta’s ability to adjust blood supply in response to changing carbon dioxide levels in the mother’s blood.
Researchers at Children’s Hospital Los Angeles, who contributed to the study, found that PLVR was significantly lower in pregnancies affected by CHD compared to those with healthy fetuses. The study involved 103 pregnant women, with 31 carrying fetuses diagnosed with CHD and 72 with healthy fetuses. Pregnant women in the CHD group were, on average, further along in their pregnancies (34 ± 2.9 gestational weeks) than those in the non-CHD group (30.7 ± 4.9 gestational weeks), a difference attributed to the typical timing of CHD diagnosis.
PLVR is quantified using blood oxygen level-dependent (BOLD) MRI, which measures the fetally-mediated placental response to transient changes in maternal carbon dioxide (CO2). The study utilized a general linear model to compute PLVR, analyzing the correlation between MRI signal and EtCO2 stimulus. Global PLVR was calculated as the average of voxel-wise PLVR measurements across the placenta.
The research indicates that impaired PLVR may reflect reduced vascular integrity within the placenta in pregnancies complicated by CHD. Researchers observed a PLVR of 0.024 ± 0.02 ∆BOLD/mmhg CO2 in the CHD group, compared to 0.03 ± 0.04 ∆BOLD/mmhg CO2 in the non-CHD group. The findings corroborate previous histopathologic studies that have identified placental abnormalities in cases of CHD.
The study also revealed a complex interaction between maternal diabetes and PLVR, with differing effects observed in pregnancies with and without CHD. Researchers are currently investigating the correlation between PLVR measurements and long-term fetal and infant outcomes in CHD cases. The research team at the University of Southern California, which also contributed to the study, is continuing to refine the MRI technique and explore its potential for broader clinical application.
