产前MRI诊断胎儿中线处硬脑膜窦畸形

Prenatal MRI diagnosis of fetal midline dural sinus malformation

目的探讨胎儿中线处硬脑膜窦畸形的产前MRI表现。方法收集11胎中线处硬脑膜窦畸形胎儿,经产前超声检查于孕21~27周发现胎儿枕部或小脑区异常,之后1周内接受MR平扫。11胎中,9胎经引产病理证实,2胎出生后随访复查证实。分析胎儿硬脑膜窦畸形影像表现及病理特点。结果 11胎中线处硬脑膜窦畸形,MRI均表现为枕部颅板下窦汇区囊状扩张,约10mm×15mm^35mm×55mm,邻近静脉窦亦可见扩张;轴位和冠状位MRI上病灶呈楔形,矢状位上呈纺锤状或新月形;病灶T1WI呈等或稍高信号,T2WI呈稍低-等或稍高信号。其中9胎硬脑膜窦畸形内可见血栓形成,为类圆形或条块状,偏于囊性肿物一侧壁上,T1WI呈高信号,T2WI呈低、等或高信号;6胎血栓周围见含铁血黄素沉积。2胎硬膜窦横径超过30mm,邻近脑实质及小脑受压向前移位。9胎引产后胎儿尸体解剖显示畸形扩大的静脉窦,其中7胎见偏心性血栓,周围可见分支血管。2胎出生后婴儿脑实质均发育正常。结论产前MRI可准确诊断胎儿中线处硬脑膜窦畸形,同时可评估大脑发育状况,有助于评估胎儿预后。

Objective To explore prenatal MRI findings of fetal midline dural sinus malformation（DSM）. Methods Eleven fetuses of midline DSM were collected. Abnormalities in the fetal occipital or cerebellar area were found from 21 to 27 weeks of gestation. Then MR scanning in the following week was performed. Of all 11 fetuses, 9 were pathologically proved to be midline DSM, and the other 2 were followed up and proved after birth. The imaging findings and pathological features were analyzed. Results MRI of 11 fetuses showed cystic dilation of the occipital cranium of torcular herophili area, with the size of 10 mm×15 mm to 35 mm×55 mm, and the adjacent sinuses were also dilated. On axial or coronal images, the lesions were cuneiform, while on sagittal images, the lesions were spindle-or crescent-shaped. The lesions displayed isointensity or slightly hyperintensity on T1WI, while slightly hypointensity, isointensity or slightly hyperintensity on T2WI. In 9 of the 11 fetuses, class round or bar thrombosis on the side wall of the cystic mass were observed, which were hyperintensity on T1WI and isointensity and hypointensity, isointensity or hyperintensity on T2WI. Hemosiderin deposition was observed around the thrombi in 6 fetuses. Lesion diameters in 2 fetuses were more than 30 mm, and the adjacent brain tissue was significantly dislocated. Nine fetuses of postmortem pathology after induced labor showed deformed and dilated venous sinuses, in which eccentric thrombi were seen in 7 fetuses with side branches around them. Normal brain development was observed in 2 live birth newborns. Conclusion Prenatal MRI can accurately diagnose fetal midline dural sinus malformation, and estimate the development of fetal brain, which may be helpful to prognosis prediction.