产前胎盘植入的MR表现与诊断价值

MR Findings of Placental Implantation and Its Prenatal Diagnostic Value

目的探讨产前胎盘植入MRI表现及其诊断价值。方法收集105例临床疑产前胎盘植入患者相关资料,包括妊娠史等一般资料、术前MRI和超声所见和诊断、手术和/或病理结果,以手术和/或病理结果为参照标准,分析胎盘植入的主要MRI征象,评估MRI与超声预测胎盘植入的诊断效能;评价MRI与手术或病理分型诊断的一致性。结果 105例疑有胎盘植入患者中,病理证实有胎盘植入的45例,其中穿透性植入22例、肌层植入13例、胎盘粘连10例;MR拟诊阳性或可疑阳性74例。MR评估产前胎盘植入的灵敏度0.98、特异度0.48、阳性预测值0.55、阴性预测值0.97;超声产前胎盘植入的灵敏度0.52、特异度0.86、阳性预测值0.76、阴性预测值0.73,两者差异有统计学意义,P值<0.05。在产前胎盘植入的MR各种征象中,子宫肌层与胎盘结构分界不清的有51例,真阳性者36例,假阳性者15例,准确率71%;胎盘与膀胱壁分界不清的有3例,准确率100%;其他征象都相对少见或价值有限。结论 MRI对产前胎盘植入诊断灵敏度较超声好,但特异度低于超声。采用MRI对胎盘植入进行诊断时,可显示多种相关征象,其中膀胱壁与胎盘结构分界不清为诊断胎盘植入的最可靠征象。

Objective To investigate the MR imaging findings of placental implantation and its prenatal diagnostic value.Methods Data of 105 patients with suspicion of placental implantation who had undergone MR and color Doppler ultrasound(US)evaluation in the second and third trimester gestation were collected retrospectively,including MRI findings and color Doppler ultrasonography of the placental implantation,the prenatal diagnosis,surgical evidence,pathological diagnosis,and so on.Taking surgical evidence or histopathology as reference,the sensitivity,specificity,positive predictive value,negative predictive value and accuracy of MRI and US for the evaluation of placental implantation were determined.Results Of the 105 patients with suspicion of placenta implantation,45 cases were consistent with pathology,including 22 cases of penetrating implantation,13 cases of myometrium placenta implantation,and 10 cases of placenta adhesion;and 74 patients were assumed placenta accrata or suspected placenta accrata based on MRI.The sensitivity,specificity,positive predictive value,and negative predictive value of MRI and US for the evaluation of placenta implantation were 0.98 and 0.52,0.48 and 0.86,0.55 and 0.76,and 0.97 and 0.73,respectively(P<0.05).On MRI imaging,51 patients showed lose of or ambiguous and blurry placental myometrial interface,36 of them had placenta implantation,15 of them did not have placenta implantation,and the accuracy was 71%.3 patients with lose of the placental urinary bladder interface showing on the contrast-enhanced MRI were confirmed placenta implantation,the accuracy was 100%;the other abnormal findings on MRI were relatively rare,and they had limited value for the evaluation of placenta implantation.Conclusion Compared with color Doppler ultrasonography for the evaluation of placenta implantation,MRI has higher sensitivity and lower specificity.The lose of the placental urinary bladder interface on the contrastenhanced MRI is a reliable characteristic for the diagnosis of placenta implantation.