Quantitative Ultrasound-Based Characterization of Placental Tissue Microstructure in a Rat Model of Preeclampsia

Quantitative ultrasound (QUS) methods were applied to detect changes in placental microstructure in the reduced uterine perfusion pressure (RUPP) model of preeclampsia in rats. Preeclampsia is a life-threatening pregnancy disorder associated with abnormal placental development that is inadequately treated and managed.

Nine timed-pregnant Sprague-Dawley rats were used in this study. On gestational day 14 (GD 14), five rats received RUPP surgery to induce preeclampsia. US radiofrequency data were acquired for QUS analysis on GD18. On GD19, animals were sacrificed and dissected to acquire placental tissue samples. The cell nuclear diameter in each anatomical layer of the placenta was measured to compare with regional effective scatterer diameter (ESD) values.

ESD measurements obtained using in vivo QUS imaging correlated well (R² = 0.58, p = 3.8e-6) with cell nucleus diameter measurements from microscopy images. RUPP placentas had significantly smaller junctional zones compared to control placentas (p = 0.013). The average ESD in RUPP placentas was 1.0 µm smaller compared to control placentas (p = 0.040). This decrease in ESD in RUPP placentas is consistent with the decreased size of the junctional zone, which, in comparison to the labyrinth zone and chorionic plate, has larger cell nuclei (p = 3.3e-21 and p = 9.5e-27, respectively) and larger ESD (p = 5.6e-4 and p = 4.5e-8, respectively).

These results demonstrate the potential of QUS as a non-invasive tool for detecting critical changes in placental microstructure, improving maternal and fetal outcomes by enabling earlier diagnosis and more timely therapeutic interventions in preeclampsia.