不同b值扩散加权成像在植入性胎盘中的诊断价值

Diagnostic value of diffusion weighted imaging with different b value in placenta accreta

目的探讨磁共振扩散加权成像(DWI)在诊断植入性胎盘中的应用价值。方法回顾性分析2012年3月至2015年12月在南宁市第一人民医院临床疑似植入性胎盘妊娠中晚期孕产妇及中孕引产胎盘滞留患者93例的MRI图像资料,以术后病理及分娩或手术记录作为金标准,采用方差分析的方法比较各b值组之间胎盘植入区域与子宫肌壁区域的信号强度比(SI Ratio)。结果当b值选取600 s/mm^2时,胎盘植入区域与子宫肌壁区域的SI Ratio最高,为(6.05±1.36),与b值为0 s/mm^2、400 s/mm^2、800 s/mm^2、1 000 s/mm^2时相比,差异有统计学意义(P<0.05);胎盘黏连在DWI图像上表现为底蜕膜即胎盘母体面的线状低信号影模糊,胎盘母体面可局限性突起,但子宫肌层连续性完整;胎盘植入DWI图像显示胎盘母体面结节状或块状突出、胎盘附着肌层缺失;胎盘穿透在DWI图像上显示胎盘组织穿透子宫肌层并位于其信号带以外。结论常规MRI扫描结合DWI检查在一定程度上提高植入性胎盘及其类型的诊断准确率,当b值选取600 s/mm^2时,DWI对于胎盘植入具有较高的显示效果,为临床治疗提供可靠的依据。

Objective To evaluate the value of diffusion weighted imaging（DWI） in diagnosis of placenta accreta. Methods MRI findings in 93 pregnant and retained placenta women with suspected placenta accreta were evaluated from March 2012 to December 2015. According to the surgical or pathological results, variance analysis was used to compare the signal intensity ratio（SI ratio） of placenta implantation region and myometrial wall region between different b value groups. Results When the b value was 600 s/mm2, the SI ratio was the highest（6.05±1.36）, which was significantly higher than that at b value of 0 s/mm2, 400 s/mm2, 800 s/mm2, 1 000 s/mm2（P0.05）. On DWI images, placenta adhesion showed fuzzy linear low signal on decidua basalis（the maternal surface of placenta）, with localized protrusions, and continuous completeness on myometrium. On DWI images, placenta accreta showed nodular or massive protrusions on the maternal surface of placenta and placental muscle loss. Placenta percreta showed that the signal of the placenta display outside of the uterine muscle in the DWI image. Conclusion When conventional MRI was combined with DWI, the diagnosis accuracy of placenta accreta can be improved. The display effect is the best when b value was600 s/mm2.