Novel image approaches to placental insufficiency Studies in the reduced uterine perfusion pressure (RUPP) rat model

Placental insufficiency underlies major obstetric complications including preeclampsia and fetal growth restriction. Clinical assessment remains largely indirect, relying on ultrasound surveillance rather than direct measures of placental function. This thesis uses reduced uterine perfusion pressure (RUPP) rat model to investigate how reduced uterine perfusion reshapes placental structure, perfusion, and oxygenation across gestation using an integrated multimodality imaging approach.
Pregnant Sprague Dawley rats were randomized to RUPP or normal pregnant groups. Placental function was assessed using T2* MRI, 3D dynamic contrast-enhanced MRI, contrast-enhanced ultrasound, and photoacoustic imaging at different gestational timepoints, complemented by histological analysis of the maternal–fetal interface.
Key findings reveal that placental insufficiency in the RUPP model follows a temporally evolving trajectory. Immediately after RUPP induction at gestational day (GD)14, severe perfusion impairment occurs with delayed contrast arrival and impeded wash-out. By mid-gestation (GD 16), perfusion metrics normalize despite established structural abnormalities including impaired spiral artery remodeling, shallow trophoblast invasion, and persistent uterine natural killer cells. Late-gestation imaging (GD 19) shows preservation of perfusion parameters yet reduced placental oxygenation, indicating chronic hypoxia arising from structural vascular maladaptation rather than insufficient inflow alone.