The Value Of IVIM For Placental Perfusion Measurement In Normal Middle And Late Pregnancy With 3.0T Magnetic Resonance

Objective:To study the measurement repeatability of In Vivo Inferior Motion（IVIM）for normal placental perfusion with MRI,the influence of gestational age on normal placental perfusion and the difference of perfusion in different regions of the placenta.Methods:Forty-eight pregnant women with normal singleton confirmed by ultrasound were enrolled.All volunteers were divided into three groups according to gestational ages（GA）including groupⅠ（GA 15-27 weeks,n=27）;groupⅡ（GA 28-33 weeks,n=11）;groupⅢ（GA 34-39 weeks,n=10）.Conventional magnetic resonance imaging and IVIM imaging were performed in all pregnant women in the 3.0T MRI scanner.The f-values（perfusion fraction）of the three different regions including the base,the center,and the fetal side of the placenta were observed by two radiologists in IVIM imaging.The performance consistency of two radiologists was analyzed using the Interclass Correlation Coefficient（ICC）.The difference of placenta perfusion in three parts of placenta and the correlation of perfusion coefficient and gestational age were analyzed.Results:The average gestational age of 48 pregnant women was 27⁺³weeks.The good consistency of two radiologist for perfusion measurement in three parts of placenta with IVIM were observed.The Interclass Correlation Coefficient of perfusion measurement between two radiologist in three parts of placenta were 0.935（the fetal side）,0.941（the middle）and 0.973（the base）,P<0.05 respectively.There were significant differences of placeta perfusion fraction in three parts of placenta including fetal side（37.04±7.02）%,the middle（37.41±6.83）%and the fetal side（46.55±6.36）%,P<0.05.The negatively correlation were found between gestational age and the perfusion fraction（f）of fetal side（r=-0.547,P<0.05）,and the middle（r=-0.616,P<0.05）,respectively.There was no correlation between gestational age and perfusion fraction（f value）of the base of placenta（r=-0.035,P>0.05）.Conclusion:The good repeatability was showed for evaluating placenta perfusion with IVIM model.The perfusion fraction（f）in IVIM imaging can be used as a new index for observing placental perfusion in pregnant women with contraindications to contrast agents.The value of placental perfusion varies according the gestational age and the different location of the placenta.