探讨产前MRI检查在胎盘植入性疾病(PAS)诊断中的应用价值。

选择2018年1月至2019年12月，于成都市第三人民医院经临床及超声检查疑诊为PAS后，并进一步接受产前MRI检查的68例疑似PAS患者为研究对象。采用回顾性分析方法，采集其产前MRI影像学资料。以这68例受试者子宫切除术后切除组织的病理学检查结果为诊断PAS的"金标准"，计算产前MRI辅助诊断PAS及对PAS进行分类(胎盘黏连、胎盘植入、穿透性胎盘植入)的敏感度、特异度。采用Kappa值，分析产前MRI辅助诊断与子宫切除术后切除组织的病理学检查结果诊断PAS及其分类结果的一致性。对经组织病理学检查确诊的PAS患者的MRI影像学资料进行分析。本研究遵循的程序符合2013年新修订的《世界医学协会赫尔辛基宣言》要求。

①本组68例受试者中，56例经术后组织病理学检查确诊为PAS患者。采取产前MRI辅助诊断PAS的结果显示，54例呈阳性(PAS)患者中，1例经术后组织病理学检查结果证实不是PAS；14例呈阴性(非PAS)患者中，3例经术后组织病理学检查结果证实为PAS(均为胎盘黏连)患者。以术后组织病理学检查结果为诊断PAS的"金标准"，产前MRI检查对于PAS及其3种分类(胎盘黏连、胎盘植入、穿透性胎盘植入)辅助诊断的敏感度分别为94.6%、44.4%、97.6%与40.0%，特异度分别为91.7%、98.3%、76.9%与100.0%。产前MRI检查与术后组织病理学检查结果，对于PAS的诊断一致性较高，Kappa值为0.810；对于胎盘黏连、胎盘植入、穿透性胎盘植入辅助诊断的Kappa值分别为0.527、0.774、0.553。②经术后组织病理学检查结果确诊为PAS的56例患者的MRI影像学资料中，出现胎盘组织侵入子宫肌层，胎盘组织侵入膀胱、输尿管等盆腔内组织，T2WI低信号带，胎盘信号不均匀，子宫下段膨隆，以及膀胱"帐篷征"表现者，分别为14例(25.0%)、8例(14.3%)、38例(67.9%)、33例(58.9%)、16例(28.6%)与7例(12.5%)。

产前MRI检查，可对PAS进行影像学辅助诊断及分类，从而为临床针对PAS患者制定个体化治疗方案，改善其预后，提供一定参考。

To explore application value of prenatal MRI in detecting placenta accreta spectrum disorders (PAS).

A total of 68 suspected PAS patients by clinical and ultrasound examinations who received prenatal MRI detecting in the Third People′s Hospital of Chengdu from January 2018 to December 2019 were selected as research subjects. Their prenatal MRI data were retrospectively collected. Based on results of histopathological examination after operation as the " golden standard" for PAS diagnosis, the sensitivity and specificity of prenatal MRI auxiliary diagnosis of PAS and its three kinds of classifications (placenta adhesion, placenta implantation, placenta percreta) were calculated. The Kappa value was used to evaluate the consistency of prenatal MRI auxiliary diagnosis results and results of histopathological examination after operation in diagnosis of PAS and its three kinds of classifications for all subjects. The MRI data of PAS patients confirmed by results of histopathological examination after operation were analyzed. The procedures in this study were in line with the requirements of World Medical Association Declaration of Helsinki revised in 2013.

①Among 68 subjects, 58 of them were confirmed as PAS by results of histopathological examination after operation. Auxiliary diagnosis results of prenatal MRI showed that 54 cases were positive (PAS patients), and one case of them was confirmed as without PAS by results of histopathological examination after operation, while 14 cases were negative (non-PAS patients), and 3 cases of them were confirmed as PAS by results of histopathological examination after operation (all were placental adhesion patients). With results of histopathological examination after operation as the golden standard of PAS diagnosis, the sensitivities of prenatal MRI for auxiliary diagnosis of PAS and its three kinds of classifications (placenta adhesion, placenta implantation, placenta percreta) were 94.6%, 44.4%, 97.6% and 40.0%, respectively, the specificities were 91.7%, 98.3%, 76.9% and 100.0%, respectively. Kappa consistency analysis showed a high consistency between results of prenatal MRI and histopathological examination after operation (Kappa value=0.810). The Kappa values for each PAS classification (placenta adhesion, placenta implantation, placenta percreta) were 0.527, 0.774, and 0.553, respectively. ②Among the prenatal MRI data of 56 cases of PAS patients confirmed by results of histopathological examination after operation, 14 cases (25.0%) showed signs of placental tissue invading the myometrium, 8 cases (14.3%) showed signs of placental tissue invading the pelvic tissues such as bladder and ureter, 38 cases (67.9%) showed low signal band on T2WI, 33 cases (58.9%) showed signs of inhomogeneous placental signal, 16 cases (28.6%) showed signs of swelling in the lower uterus, and 7 cases (12.5%) showed bladder tent signs.

Prenatal MRI examination can play the role of auxiliary diagnosis of PAS and its classifications, and provide reference for individualized treatment methods for PAS patients, and improve their prognosis.