Visualization and Quantification of Placental Vasculature Using MRI

Visualization of the placental vasculature in vivo is important for parameterization of placental function which is related to obstetric pathologies such as fetal growth restriction (FGR). However, most analysis of this vasculature is conducted ex vivo after delivery of the placenta. The aim of this study was to determinewhether in vivo MRI imaging can accurately quantify the feto-placental vasculature, and to determine the impact of MRI contrast on its identification. Six different MRI contrasts were compared across 10 different cases. Image quality metrics were calculated, and analysis of vasculature segmentations performed. Measures of assessment included the vessel radius distribution, vessel connectivity and the identification of vessel loops. T-2 HASTE imaging performed the best both qualitatively, and quantitatively for PSNR and connectivity measures. A larger number of segmented branches at the smallest radii were observed, indicative of a richer description of the in vivo vascular tree. These were then mapped toMR perfusion fraction measurements from intra-voxel incoherent motion (IVIM) MRI. Mapped results were compared to measures extracted from gold-standard ex vivo micro-CT of the placenta and showed similar vessel density patterns suggesting that placental vessel analysis may be feasible in vivo.