Placental Vascular Function Across Imaging Scales: Comparative Insights from Contemporaneous MRI and Doppler Ultrasound

Background : The placenta plays a critical role in fetal development. This study investigates correlations between contemporaneous Doppler ultrasound (US) and magnetic resonance imaging (MRI) measures of placental and fetal vascular function in pregnancies with normally developing fetuses. Method : In this prospective study, 56 pregnant women at 20–39 weeks' gestation underwent Doppler US (uterine artery, umbilical artery and vein, middle cerebral artery, ductus venosus) and placental MRI (spatial variance, temporal variance, vascular reactivity) within 30 minutes of each other. Pearson's correlation assessed associations between US and MRI measures, and regression models tested the impact of maternal risk factors on these correlations. Results : Umbilical vein (UV) velocity correlated positively with MRI spatial and temporal variance (r=0.45 and r=0.33, p<0.05), and umbilical artery pulsatility index (UA-PI) negatively correlated with spatial variance (r=-0.35, p<0.05). These correlations persisted in the presence of maternal risk factors except for maternal diabetes. Higher pregravid BMI was associated with increased UA-PI (p=0.039) and diabetes with lower UV velocity (p=0.036). Conclusion : Correlations between UA-PI, UV velocity, and MRI spatial and temporal variance suggest that these interrelated metrics capture complementary aspects of feto-placental micro- and macrovascular function and may improve assessment of placental health.