Magnetic Resonance Imaging Measurement of Placental Perfusion and Oxygen Saturation in Early-Onset Fetal Growth Restriction

OBJECTIVE: We hypothesised that a multi-compartment magnetic resonance imaging (MRI) technique that is sensitive to fetal blood oxygenation would identify changes in placental blood volume and fetal blood oxygenation in pregnancies complicated by early-onset fetal growth restriction (FGR). DESIGN: Case–control study. SETTING: London, UK. POPULATION: Women with uncomplicated pregnancies (estimated fetal weight [EFW] >10th centile for gestational age [GA] and normal maternal and fetal Doppler ultrasound, n = 12) or early- onset FGR (EFW <3rd centile with or without abnormal Doppler ultrasound <32 weeks GA, n = 12) were studied. METHODS: All women underwent MRI examination. Using a multicompartment MRI technique, we quantified fetal and maternal blood volume and feto-placental blood oxygenation. MAIN OUTCOME MEASURES: Disease severity was stratified according to Doppler pulsatility index and the relationship to the MRI parameters was investigated, including the influence of GA at scan. RESULTS: The FGR group (mean GA 27(+5) weeks, range 24(+2) to 33(+6) weeks) had a significantly lower EFW compared with the control group (mean GA 29(+1) weeks; –705 g, 95% CI –353 to –1057 g). MRI-derived feto-placental oxygen saturation was higher in controls compared with FGR (75 ± 9.6% versus 56 ± 16.2%, P = 0.02, 95% CI 7.8–30.3%). Feto-placental oxygen saturation estimation correlated strongly with GA at scan in controls (r = –0.83). CONCLUSION: Using a novel multimodal MRI protocol we demonstrated reduced feto-placental blood oxygen saturation in pregnancies complicated by early-onset FGR. The degree of abnormality correlated with disease severity defined by ultrasound Doppler findings. Gestational age-dependent changes in oxygen saturation were also present in normal pregnancies.