(209) Feasibility of Non-Invasive Oxygenation and Cotyledon-Specific Perfusion Measurements of Rhesus Macaque Placenta with Magnetic Resonance Imaging in a Thrombotic Injury Model

Ruo-Yu Liu¹, Logan T. Keding^2,3, Jessica Vazquez^2,3, Ruiming Chen¹, Ante Zhu⁴, Daniel Seiter¹, Kathleen Antony³, Heather A. Simmons^2,5, Puja Basu², Andres F. Mejia², Aleksandar K. Stanic³, Dinesh M. Shah³, Diego Hernando^1,4, Kevin M. Johnson^1,4, Thaddeus G. Golos^2,3,5, and Oliver Wieben^1,4

1. Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

2. Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI, United States

3. Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, United States

4. Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States

5. Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, United States

Abstract Text:

Motivation: Abnormalities in placental blood flow, perfusion and oxygenation can lead to gestational complications. The capacity to non-invasively detect these abnormalities early in pregnancy could potentially enable timely intervention and improve pregnancy outcomes. Magnetic resonance imaging (MRI) provides much higher resolution than conventional ultrasound without ionizing radiation and thus is a strong candidate for placenta imaging. Goals: To assess the local effects of thrombotic placental injury model in the rhesus macaque by pathology and the feasibility of MRI to non-invasively evaluate perfusion restriction and/or insufficient oxygenation and their correlations. Approach: We introduce a novel thrombotic placental injury model in rhesus macaques. Tisseel (n=3) or saline (n=4) was injected into rhesus macaque placentas. Placental perfusion domains and cotyledon-specific perfusion were obtained longitudinally with ferumoxytol dynamic contrast-enhanced MRI, and oxygenation information was obtained with blood oxygenation level dependent (BOLD) MRI and quantitative R2* mapping. The pathology of each cotyledon was analyzed in detail, and physical cotyledons were matched with the perfusion domains identified in MRI for localized comparisons.

Results: Larger areas of fibrin deposition, inflammatory injury, and calcification were observed in the cotyledon center-cuts of Tisseel-treated placentas, accompanied by larger overtime and post-contrast increase in R2* values and lower perfusion at the cotyledon level. Meanwhile, the inter-group difference in whole-placental perfusion was insignificant. Impact: Effects of the placental thrombosis model were confirmed, and comparisons of placental histopathology, perfusion, and oxygenation were proven feasible. Different perfusion relations with pathology on placental and cotyledon levels suggest the plasticity of the placenta under injury, which would be of significant value in predicting and monitoring pregnancy complications.