Primary study of DWI in evaluation of placental maturity in the second and third trimesters of pregnancy / 实用放射学杂志

ABSTRACT

Objective To investigate the value of routine MRI in determining placental grading and the relationship between placental apparent diffusion coefficient(ADC)value and the gestational age(GA)in the second and third trimesters of pregnancy. Methods 52 women with singleton pregnancies were referred for MRI examination for underlying maternal or fetal lesions or malformations identified by ultrasound(US).Subjects were divided into three groups according to the GAgroup Ⅰ at 18 -26 weeks(n=29);groupⅡat 27-33 weeks(n=14);group Ⅲ at 34-40 weeks(n=9).DWI protocol included 2 sets of b-values0 s/mm2,200 s/mm2,800 s/mm2 and 50 s/mm2,200 s/mm2,800 s/mm2,and ADC values of the two groups were calculated and correlated with GA by simple linear regression.Results Half-fourier acquisition single-shot turbo spin-echo(HASTE)sequence could clearly define the 3 layers of placenta and determine the grading of placental aging.ADC values with b values of 0 s/mm2,200 s/mm2and 800 s/mm2were correlated negatively with GA (r= -0.900,P<0.001).However,ADC values with b values of 50 s/mm2,200 s/mm2and 800 s/mm2did not show any statistical correlation with GA(r= -0.037,P=0.795).Conclusion MRI can visualize the morphological changes of the placenta during the pregnancy.With a set of b-values at 0 s/mm2,200 s/mm2and 800 s/mm2,placental ADC values are found to have decreasing tendency as the pregnancies progress in the second and third trimesters.