目的分析凶险性前置胎盘植入 产前MRI诊断的影像特征及诊断价值。方 法 选择我院收治的凶险性前置胎盘患者 71例，产前均进行MRI检查，以剖宫产手 术和病理为诊断标准，分析凶险性前置胎 盘植入MRI影像学表现及诊断价值。结果 71例凶险性前置胎盘患者经手术病理确诊 为单纯凶险性前置胎盘患者23例，凶险性 前置胎盘植入者48例(13例为胎盘粘连， 30例为胎盘植入，5例为胎盘穿透)，后者 MRI图像有35例可见胎盘内信号不均，20 例子宫外突，33例胎盘与子宫肌层交界不 清，25例T2WI呈低信号，25例胎盘内血管 影增多、增粗，13例膀胱突起。MRI对凶 险性前置胎盘植入检测灵敏度为85.41%， 特异度为82.61%，准确度为84.51%。MRI 对粘连型诊断灵敏度为53.85%，特异度为 93.10%；对植入型诊断灵敏度为86.67%， 特异度为92.68%；对穿透型诊断灵敏度为 80.00%，特异度为98.48%。结论 MRI对凶 险性前置胎盘植入检出率较高，且对植入 型和穿透型诊断灵敏度和特异度高于粘连 型，可作为临床诊断凶险性前置胎盘植入 及其分型的重要方法。

Objective To analyze the imaging features and diagnostic value of prenatal MRI diagnosis of dangerous placenta previa implantation. Methods 71 cases of patients with dangerous placenta previa admitted to our hospital were selected, and they were examined by MRI before delivery. The cesarean section and pathology were used as diagnostic criteria to analyze the MRI imaging findings and diagnostic value of dangerous placenta previa implantation. Results Among 71 cases of patients with dangerous placenta previa, there were 23 cases of pure dangerous placenta previa and 48 cases of dangerous placenta previa implantation (13 cases of placental adhesions, 30 cases of placenta accreta and 5 cases of placenta penetration), and the latter MRI images showed 35 cases with uneven signal within the placenta, 20 cases with uterine protrusion, 33 cases with unclear junction between placenta and myometrium, 25 cases with low signal on T2WI, 25 cases with increased and thickening placental vascular shadow and 13 cases with bladder protrusion. The sensitivity, specificity and accuracy of MRI were 85.41%, 82.61% and 84.51% in detecting dangerous placenta previa implantation. The diagnostic sensitivity and specificity of MRI were 53.85% and 93.10% for adhesion type, and were 86.67% and 92.68% for the implantable type, and were 80.00% and 98.48% for penetrating type. Conclusion MRI has a high detection rate for dangerous placenta previa implantation, and the diagnostic sensitivity and specificity of implantable type and penetrating type are higher than those of adhesion type. And it can be used as an important method for the clinical diagnosis of dangerous placenta accreta implantation and its types.