In vivo assessment of the placental anatomy and perfusion in a mouse model of intrauterine inflammation

Background Magnetic resonance imaging (MRI) provides useful markers to examine placental function. MRI features of placental injury due to intrauterine inflammation—a common risk during pregnancy, are not well known. Purpose To investigate the capability of structural MRI and intravoxel incoherent motion (IVIM) imaging in examining acute placental injury in a mouse model of intrauterine inflammation, as well as gestation‐dependent placental changes. Study Type Prospective study. Animal Model Pregnant CD1 mice were scanned on embryonic day 15 (E15, n = 40 placentas from six dams) and E17. On E17, mice were subjected to intrauterine injury by exposure to lipopolysaccharide (LPS, n = 25 placentas from three dams) or sham injury (n = 25 placentas from three dams). Field Strength/Sequence In vivo MRI was performed on an 11.7T Bruker scanner, using a fast spin‐echo sequence and a diffusion‐weighted echo‐planar imaging (EPI) sequence. Assessment T2‐weighted MRI was acquired to evaluate placental volume. IVIM imaging was performed in a restricted field‐of‐view using 15 b‐values from 10–800 s/mm2, based on which, the pseudodiffusion fraction (f), pseudodiffusion coefficient (D*), and tissue water coefficient (D) were estimated with a two‐step fitting procedure. Statistical Tests Two‐way analysis of variance (ANOVA) was used to evaluate the group differences. Results The placental volume increased by ∼21% from E15 to E17 (P < 0.01), and a 15% volume loss was observed at 6 hours after LPS exposure (P < 0.01). IVIM parameters (f, D*, and f·D*) were similar between the E15 and E17 sham groups (P > 0.05), which was significantly reduced in the LPS‐exposed placentas compared to the shams (P < 0.001). D values decreased from E15 to E17 (P < 0.05), which were further reduced after LPS exposure (P < 0.05). Changes in placental area and vascular density were histologically identified in the LPS‐exposed group, along with gestation‐dependent changes. Data Conclusion Our results suggested structural MRI and IVIM measurements are potential markers for detecting acute placental injury after intrauterine inflammation. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1260–1267.