超声对11~13+6周胎儿颅后窝病变的诊断价值

Diagnostic value of ultrasound in fetal posterior fossa anomalies at 11-13+6 gestational weeks

目的探讨超声测量孕11~13+6周胎儿脑干(BS)宽度、脑干-枕骨(BSOB)宽度及BS与BSOB比值(BS/BSOB)对胎儿颅后窝病变的诊断价值。方法随机抽取2018年3月至2021年11月于首都医科大学附属北京妇产医院建档的11~13+6周正常单胎胎儿209例(对照组),于颜面正中矢状切面上测量BS宽度、BSOB宽度,计算BS/BSOB,分析三者与头臀长(CRL)的相关性。采用组内相关系数(ICC)对30例正常胎儿进行观察者内和观察者间的一致性检验。回顾性分析同期诊断的颅后窝异常胎儿14例(异常组),包括颅后窝囊性病变(cPFM)10例,开放性脊柱裂(OSB)4例,比较异常组与对照组BS宽度、BSOB宽度及BS/BSOB的差异。结果对照组BS宽度和BSOB宽度显示率为100%,BS宽度、BSOB宽度与CRL呈线性相关(r=0.867、0.794,均P<0.001),BS/BSOB与CRL无明显相关性,BS/BSOB为0.75(0.71,0.79)。BS宽度及BSOB宽度的观察者内和观察者间的一致性好(ICC=0.877、0.846和0.939、0.895)。对照组与异常组相比,BSOB宽度和BS/BSOB差异有统计学意义(均P<0.05)。其中,除1例单纯性小脑蚓部发育不良外,9例(90%)cPFM胎儿的BSOB宽度大于对照组胎儿的第95百分位数,4例(100%)OSB胎儿的BSOB宽度小于对照组胎儿的第5百分位数;除1例单纯性小脑蚓部发育不良外,9例(90%)cPFM胎儿的BS/BSOB值均小于对照组的第5百分位数,4例(100%)OSB胎儿的BS/BSOB均大于第95百分位数。结论早孕期超声测量胎儿BS宽度和BSOB宽度是可行的,具有良好的可重复性。胎儿BSOB宽度和BS/BSOB异常对颅后窝异常具有提示作用。单纯性小脑蚓部发育不良的早孕期颅后窝超声可无异常表现。

Objective To explore the diagnostic value of ultrasound in posterior fossa anomalies(PFA)at 11-13+6 gestational weeks by measuring brainstem(BS),brainstem-to-occipital bone(BSOB)diameter and BS/BSOB ratio.Methods A total of 209 normal fetuses(control group)were randomly selected from Beijing Obstetrics and Gynecology Hospital,Capital Medical University,between March 2018 and November 2021.Reference ranges for BS,BSOB diameter and BS/BSOB ratio were obtained on the mid-sagittal view of the fetal profile and the relationship of three parameters and crown-rump length(CRL)was investigated.The intra-and inter-observer reliabilities were determined by intraclass correlation coefficient(ICC)in 30 normal fetuses.Fourteen fetuses diagnosed with PFA in the same period including 10 cases of cystic posterior fossa malformations(cPFM)and 4 cases of open spine bifida(OSB)were retrospectively selected to compare BS,BSOB diameter and the BS/BSOB ratio with control group.Results BS and BSOB diameters were successfully obtained in all control fetuses(100%),and the intra-and inter-observer reliabilities for BS and BSOB diameters were good(ICC=0.877,0.846 and 0.939,0.895).In the control group,BS and BSOB diameter linearly correlated with CRL(r=0.867,0.794;all P<0.001),while the BS/BSOB ratio was 0.75(0.71,0.79).There were significant differences of BSOB diameter and BS/BSOB ratio between control group and PFA group(all P<0.05).Except for one isolated vermian hypoplasia(VH),the BSOB diameters in 9(90%)cases of cPFM were above the 95th percentile of the calculated normal range and were below the 5th percentile in 4(100%)cases of OSB.Except for one isolated VH,the BS/BSOB ratio in 9(90%)cases of cPFM was below the 5th percentile of the calculated normal range.The BS/BSOB ratio in 4(100%)cases of OSB was above the 95th percentile of the calculated normal range.Conclusions The measurements of BS and BSOB diameter are feasible with good repeatability.Abnormal BSOB diameter and BS/BSOB ratio are suggestive for PFA.The posterior fossa of isolated VH can be normal in the first trimester.