Assessment of placental perfusion and oxygenation using novel MRI approaches

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Early in pregnancy migration of trophoblast cells to the lumen of the spiral arteries leads to 5-10 fold terminal dilation of the arteries, thereby increasing blood flow through the placenta. Placental insufficiency is associated with failure of this conversion of the spiral arteries, and results in the most common complications of pregnancy such as fetal growth restriction (FGR) and preeclampsia (PE). In the management and treatment of pregnancies complicated by placental insufficiency, early and reliable detection is critical, because by the time placental dysfunction becomes evident, the pathological changes to the fetus or mother are irreversible. Numerous approaches have been suggested for identifying placental insufficiency in utero. Particularly, there have been various MRI-based methods proposed to measure placental function. However, all of prior studies deployed standard imaging schemes of brain MRI without significant optimization for the placenta or used the methods that are not very sensitive to placental abnormalities. Over the past several years, we have advanced dedicated MRI techniques for placental-specific perfusion and oxygenation measures using velocity-selective arterial spin labeling (VSASL) and quantitative susceptibility mapping (QSM), and have demonstrated promising results in our preliminary data. In this study, we will first optimize placental VSASL at 3 T for improved signal-to-noise ratio and image quality (aim 1). We will then apply our approaches of placental VSASL and QSM in pregnancies diagnosed with FGR or PE and healthy pregnancies to determine differences in placental perfusion and oxygenation between FGR/PE and controls (aim 2). Lastly, we will validate our MR imaging methods by comparing in-vivo placental measures against placental pathology and clinical outcomes (aim 3). Successful completion of this project will determine the association between placental insufficiency and altered in-vivo placental perfusion/oxygenation measurements. Ultimately, this will develop early and reliable biomarkers of placental health and disease, and will assist in developing and assessing new interventional approaches aimed to improve pregnancy outcomes.