Longitudinal 3D‐DCE MRI Assessment of Placental Perfusion Under Reduced Uterine Perfusion Pressure in Pregnant Rats

Placental insufficiency is a major cause of preeclampsia and fetal growth restriction. The reduced uterine perfusion pressure (RUPP) rat model reproduces cardinal features of these disorders, but longitudinal changes in placental perfusion after RUPP are poorly documented. This study aimed to assess the acute and late effects of RUPP on placental perfusion between gestational day (GD) 14 and GD18 using 3D dynamic contrast-enhanced magnetic resonance imaging (3D-DCE MRI). Pregnant Sprague Dawley rats (n = 31) were randomized to RUPP or normal pregnant (NP) groups on GD14. 3D-DCE MRI scans were performed on GD14, GD15, and GD16 or GD18. Perfusion parameters, including time to peak (TTP), maximum enhancement (ME), wash-out percentage (WO%), initial area under the curve (iAUC), and total area under the curve (AUC), were derived from fitted signal-time curves. In addition, exploratory voxel-wise histogram analysis was performed to assess intralitter variability. At GD14, RUPP placentas showed delayed TTP (p < 0.0001), reduced ME (p = 0.03), reduced WO% (p < 0.0001), and elevated iAUC (p = 0.02). Differences persisted for TTP (p = 0.02) and WO% (p = 0.01) at GD15 but resolved by GD16-GD18. Voxel-wise analysis revealed intralitter heterogeneity, with 20% of analyzed RUPP placentas deviating from the NP template. These findings indicate that RUPP induces an acute but transient impairment of placental perfusion, with recovery by late gestation. GD14-GD15 emerge as a critical window for detecting acute perfusion impairment and evaluating interventions targeting acute injury.