目的胎盘植入为产科少见而危重的妊娠并发症，影像诊断较困难，本文旨在探讨产前胎盘植入的 MRI 表现及误诊原因。资料与方法回顾性分析经手术及病理证实的18例产前胎盘植入的 MRI 表现及分型。结果产前 MRI 疑诊15例（83.33%），表现为子宫壁明显变薄，结合带不连续，局部胎盘与子宫壁分界不清；胎盘内信号不均，可见 T2 HASTE 序列为极低信号、TruFISP 序列为高信号的增粗扭曲血管影及低信号条索影；胎盘后方可见 T1WI 高信号、T2WI 低信号血肿影。漏诊3例（16.67%）中，2例为粘连型，1例为植入型，产前 MRI 未能明确诊断。结论MRI 是诊断胎盘植入的辅助工具，MRI 对胎盘肌层植入及穿透的诊断准确率较高，而对粘连型植入诊断准确率较低。%Purpose Placenta accreta is a rare but severe pregnancy complications, and imaging diagnosis is always difficult. This paper aims to analyze the MRI manifestations of placenta accreta, and explore its misdiagnosis reasons. Materials and Methods A retrospective study was carried out on the findings and classification of MRI plain scan and diffusion weighted imaging (DWI) scan of 18 patients with placenta accreta confirmed surgically and pathologically. Results The prenatal MRI scan reported 15 patients of placenta accreta correctly (83.33%), and missed 3 (16.67%) among which 2 were with placenta accreta and the other 1 with placenta increta. The MRI of placenta accreta presented rather thin muscular layer, discontinuous junctional zone, and some unclear boundary of placenta and uterine wall; the signal of the placenta was heterogeneous, and we could see enlarged vessels of extremely low signal on T2 HASTE and high signal on TruFISP sequences, and low signal of thick intraplacental band; moreover, hematoma with high intensity on T1WI and low intensity on T2WI could be seen. DWI demonstrated uneven intensity and dark thicker intraplacenta bands in 2 cases. Conclusion As an important clinical auxiliary tool in diagnosing placenta increta, MRI has high accuracy in the diagnosis of placenta increta and placenta percreta; however, it has rather low accuracy in placenta accreta.
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