MRI扩散加权成像单指数模型ADC值评估胎盘发育的研究

Evaluation of the placental maturation with apparent diffusion coefficient

目的探讨扩散加权成像单指数模型ADC值能否可作为衡量胎盘发育成熟的可靠指标。方法收集我院MR检查的单胎妊娠孕妇66例,均先在本院或者外院行超声检查,因胎儿畸形而非胎盘病变前来就诊。其中18例因胎儿畸形引产,余48例孕周18周+1d^38周+5d,平均27周+6d,均在行超声检查后72h内行3TMR检查。先行常规T2HASTE和T1WI压脂序列扫描,然后行DWI(b=1000)。对于48例胎盘正常的病例,按照孕周分为三组,计算测量所得ADC值的平均值,使用SPSS20软件,三个孕周组间的ADC值采用Kruskal-WallisH检验进行统计学分析。结果48例正常胎盘其ADC测量值范围为(1.7231-2.1403)×10^-3mm^2/s,中位值为(1.899±0.114)×10^-3mm^2/s,两位测量者测得的胎盘的ADC值一致性较好(ICC值为0.901,P<0.05),三组不同孕周的胎盘ADC值无显著性差异(P>0.05)。结论随着孕周的增加,胎盘的ADC值保持相对稳定,ADC值不能作为衡量胎盘发育成熟与否的指标。

Objective To explore the efficacy of apparent diffusion coefficient (ADC) value for assessing placental maturation.Methods 48 women with singleton pregnancy (gestational age range: 18 weeks 1 day to 38 weeks 5 days,average: 27 weeks 6 days) underwent fetal MRI within 72 hours after conventional prenatal ultrasonography (US) demonstrated fetal malformations and normal placenta.Using a 3 T MR scanner,half Fourier single-shot turbo spin-echo (HASTE) and fat-saturated T1-weighted sequences followed by diffusion-weighted MR imaging with b value of 1000 were acquired.The women were divided into three groups according to gestational age.The ADC values were measured by 2 observers and the average ADC values of the 3 gestational age groups were compared by Kruskal-Wallis H test.Results The median ADC value of 48 normal placentas was 1.899±0.114×10^-3 mm^2/s with range of 1.723-2.140×10^-3 mm^2/s.The ADC values of placentas measured by the 2 observers were in good agreement (ICC=0.901,P<0.05).There was no significant difference in ADC values of placentas among the 3 gestational age groups (P>0.05).Conclusion With increasing gestational age,the ADC value of placenta remains relatively stable and cannot be used to measure placental maturity.