磁共振弥散加权成像对孕中晚期胎脑及其病变的诊断评估

Diffusion-weighted Imaging Evaluation of Middle and Late Pregnancy Fetal Brain with Cerebral Abnormalities

目的 通过测量不同脑区ADC值探讨MRI弥散加权成像对孕中晚期胎脑及其合并病变的诊断价值。方法 收集我院MRI检查的单胎孕妇43例,先行三平面常规T2HASTE扫描,再行弥散加权成像,分析胎儿磁共振表现并测量不同脑区的ADC值,比较两组间差异,采用Pearson相关分析不同区域ADC值与孕龄的关系。结果 43例孕妇均为单胎,正常对照组胎脑19例,病变组24例,包括脑室扩张16例;颅后窝增宽6例,蛛网膜囊肿1例,1例胎儿头围发育较小。对照组及病变组内显示脑白质区ADC值均较深部核团、脑干及小脑增高,且有统计学意义;小脑及基底节区ADC值较丘脑及脑干有统计学意义;丘脑较脑干ADC值有统计学意义。两组间比较显示病变组顶叶ADC值较对照组下降,且P<0.05。对照组枕顶叶及小脑与孕龄存在负相关,病变组丘脑、脑干及小脑与孕龄存在负相关。结论 MRI弥散加权成像可初步评估正常胎脑及合并病变的脑发育情况;病变组顶叶脑白质ADC值下降,提示该区域可能对脑部潜在损伤较敏感。

Objective To evaluation the diagnostic efficiency of Diffusion-weighted imaging(DWI) in middle and late pregnancy fetal brain with cerebral abnormalities by measuring apparent diffusion coefficient(ADC)values in different cerebral regions. Methods Half Fourier single-shot turbo spin-echo(HASTE) and DWI were performed in 43 singleton fetuses with normal or questionably fetal brain or placental lesions on sonography. ADC values in the frontal white matter(WM),temporal WM,occipital WM,parietal WM,basal ganglia,thalamus,pons and cerebellum were measured respectively,and the differences between the two groups were compared. Meanwhile,the relationship between ADC values of different regions and gestational age was analyzed by Pearson correlation analysis. Results Among 43 singleton pregnant women,19 cases of fetal brain were in the normal control group,24 cases in the lesion group,including 16 cases of ventricular dilatation;6 cases of posterior fossa widening,1case of arachnoid cyst,and one fetus had small head circumference. In the normal control group and the lesion group,the ADC values in the white matter area of the cerebral were higher than that in the deep nucleus,pons,and the cerebellum. In the two groups,the ADC values in the cerebellum and basal ganglia area were statistically significant compared with that in the thalamus and pons.Moreover,the ADC values between the thalamus and brain stem were also statistically significant.The ADC values of the lesion group decreased,and there was statistical significance in ADC values of parietal WM between the two groups(P<0.05). In the control group,occipital WM,parietal WM,and the cerebellum ADC values were negatively correlated with gestational age,while in the lesion group,thalamus,pons,and the cerebellum ADC values were negatively correlated with gestational age.Conclusion DWI could preliminarily evaluate the development of normal fetal brain and its associated lesions. The ADC value of parietal WM in the lesion group decreased,which suggest that this region may be more sensitive to potential brain injury.