Velocity-selective arterial spin labeling perfusion measurements in 2nd trimester human placenta with varying BMI

Proper placental development is crucial to fetal health but is challenging to functionally assess non-invasively and is thus poorly characterized in populations. Body mass index (BMI) has been linked with adverse outcomes, but the causative mechanism is uncertain. Velocity-selective arterial spin labeling (VS-ASL) MRI provides a method to non-invasively measure placental perfusion with robustness to confounding transit time delays. In this study, we report on the measurement of perfusion in the human placenta in early pregnancy using velocity-selective arterial spin labeling (VS-ASL) MRI, comparing non-obese and obese participants.

Participants (N = 97) undergoing routine prenatal care were recruited and imaged with structural and VS-ASL perfusion MRI at 15 and 21 weeks gestation. Resulting perfusion images were analyzed with respect to obesity based on BMI, gestational age, and the presence of adverse outcomes.

At 15 weeks gestation BMI was not associated with placental perfusion or perfusion heterogeneity. However, at 21 weeks gestation BMI was associated with higher placental perfusion (p < 0.01) and a decrease in perfusion heterogeneity (p < 0.05). In alignment with past studies, perfusion values were also higher at 21 weeks compared to 15 weeks gestation. In a small cohort of participants with adverse outcomes, at 21 weeks lower perfusion was observed compared to participants with uncomplicated pregnancies.

These results suggest low placental perfusion in the early second trimester may not be the culpable factor driving associations of obesity with adverse outcomes.