Placental multimodal MRI prior to spontaneous preterm birth <32weeks' gestation: An observational study

ObjectiveTo utilise combined diffusion‐relaxation MRI techniques to interrogate antenatal changes in the placenta prior to extreme preterm birth among both women with PPROM and membranes intact, and compare this to a control group who subsequently delivered at term.DesignObservational study.SettingTertiary Obstetric Unit, London, UK.PopulationCases: pregnant women who subsequently spontaneously delivered a singleton pregnancy prior to 32 weeks' gestation without any other obstetric complications. Controls: pregnant women who delivered an uncomplicated pregnancy at term.MethodsAll women consented to an MRI examination. A combined diffusion‐relaxation MRI of the placenta was undertaken and analysed using fractional anisotropy, a combined T2*‐apparent diffusion coefficient model and a combined T2*‐intravoxel incoherent motion model, in order to provide a detailed placental phenotype associated with preterm birth. Subgroup analyses based on whether women in the case group had PPROM or intact membranes at time of scan, and on latency to delivery were performed.Main Outcome MeasuresFractional anisotropy, apparent diffusion coefficients and T2* placental values, from two models including a combined T2*‐IVIM model separating fast‐ and slow‐flowing (perfusing and diffusing) compartments.ResultsThis study included 23 women who delivered preterm and 52 women who delivered at term. Placental T2* was lower in the T2*‐apparent diffusion coefficient model (p