胎盘植入的产前MRI表现及其病理基础

目的 探讨胎盘植入的产前MRI表现及其病理基础。 方法 收集临床诊断为前置胎盘的孕妇118例,于产前1周以MRI筛查是否并发胎盘植入;其中40例经剖宫产病理证实并发胎盘植入,回顾分析该40例患者的产前MRI表现。 结果 前置胎盘中,胎盘植入的发生率为33.90%(40/118);7例胎盘粘连型,产前MRI均未能明确诊断;22例胎盘植入型,T2WI显示植入部位子宫肌层不同程度变薄,胎盘基底面不规则,低信号的子宫肌层内可见结节状、锯齿状、不规则形高信号,其中7例T2WI胎盘内可见多量粗大的流空信号和低信号带;11例胎盘穿通型,T2WI显示胎盘穿通部位肌层信号中断,胎盘基底面与子宫壁融合,对应子宫壁外侧面完整光滑或中断毛糙,其中8例穿通部位子宫壁局部膨出,且T2WI显示胎盘内大量流空信号和粗大的低信号条带。 结论 MRI产前能明确诊断胎盘植入型、穿通型,但对粘连型胎盘植入诊断困难。

Prenatal MRI and pathological features of placental invasion

Objective To explore the prenatal MRI and pathological features of placental invasion (PI). Methods Totally 118 cases with placenta previa were collected. For screening PI, all patients underwent prenatal MRI within 1 week. PI was proved by surgery and pathology in 40 cases. MRI features of 40 patients with PI were retrospectively analyzed. Results The incidence of PI was 33.90% (40/118) in 118 patients with placenta previa. Placenta accrete of 7 patients could not be prenatally diagnosed with MRI. MRI features of 22 patients with placenta increta included myometriums thinned at the site of PI, the placenta basal surfaces were irregular, and the placental tissue invaded the myometrium in the shape of triangle, nodule or mushroom on T2WI, and dark thicker intraplacental bands and multiple flow voids were showed on T2WI in 7 patients. MRI features of 11 patients with placenta percreta included myometriums were locally discontinued, and the placental tissues were confluent with the uterine walls, and their dividing lines were not indistinct on T2WI, their perimetriums were complete and smooth, or discontinued and coarse, while the local bulging of the uterine walls, the presence of low-signal-intensity thicker intraplacental bands and multiple flow voids were showed on T2WI in 8 patients. Conclusion Placenta increta and percreta can be prenatally diagnosed with MRI, but MRI is difficult for diagnosis of placenta accreta.