Objective To explore the diagnostic value of MRI in invasively pernicious placenta previa.Methods MRI and color doppler ultrasound were performed in 1 50 patients with pernicious placenta previa.According to the operation or pathology findings, the diagnostic value of placental invasion was compared among MRI,color doppler ultrasound and both of them.Analyzed and com-pared the MRI findings of 64 patients which were confirmed as invasive placenta including adherent placenta in 20 patients,implanted one in 38 and penetrated one in 6.Results Significant difference was not found among MRI,color doppler ultrasound and both in the diagnostic value of invasive placenta (P >0.05).There was a significant difference among adherent placenta,implanted one and pen-etrated one in the diagnostic value of MRI (P <0.05),and the highest and lowest values were penetrated placenta and adherent pla-centa respectively.Conclusion MRI is an important diagnostic method in invasively pernicious placenta previa,which was useful for its classification but with a limitation for the diagnosis of adherent placenta.

ObjectiveTo investigate the MRI features of placenta accreta.MethodsFrom Apr 2009 to Jun 2011,15 patients with placenta accrete received MRI examination.In them,placenta accrcta was diagnosed based on clinical manifestations or postoperative histopathologv.The MR features of placenta accreta in thcm( study group) were retrospectively analyzed and compared with those in 15 pregnant women without placenta accreta (control group)with Fisher exact test.ResultsIn the 15 patients with placenta accreta,uterine bulging and(or) a focal outward contour bulge was detected in 14 patients; heterogeneous signal intensity in the placenta was detected in 15 patients; dark intraplacental bands on T2-weighted images was detected in 15 patients; and increased subplacental vascularity was detected in 11 patients on T1- weighted images.In the study group,14 patients showed at least three of the above four features,and in all of them uterine bulging and(or) a focal outward contour bulge,heterogeneous signal intensity in the placenta and dark intraplacental bands on T2-weighted images were detected; one patient showed heterogeneous signal intensity in the placenta,dark intraplacental bands on T2-weighted images and increased subplacental vascularity.In the control group,none patient had three of the above features.Uterine bulging and(or) a focal outward contour bulge,heterogeneous signal intensity in the placenta,dark intraplacental bands on T2-weighted images and increased subplacental vascularity were detected in 3,6,3 and 4 patients (P=0.000,0.001,0.000 and 0.027 ),respectively.ConclusionsThe main MRI features of placenta accreta are uterine bulging and(or) a focal outward contour bulge,heterogeneous signal intensity in the placenta and dark intraplacental bands on T2-weighted images Besides,increased subplacental vascularity also could provide useful information for the diagnosis of placenta accreta.

Objective ToinvestigatethevalueofpreoperativeMRIforplacentapreviainpredictionofmassivepostpartumhemorrhage. Methods AretrospectiveanalysisoftheclinicalhistoryandprenatalMRIfeaturesof362patientswithplacentapreviawereperformed. Ofthese,54casesexperiencedseverepostpartum hemorrhage.Results Univariateanalysisshowedthattheageofpregnantwomen (χ2＝3.951,P＝0.047),gestationalage(χ2＝6.257,P＝0.012),numberofcesareansections(χ2＝36.372,P＝0.001)andgemellary pregnancy(χ2＝7.933,P＝0.005)wereassociated with massivepostpartum hemorrhage.Amongthe MRIsigns,Uterinebulging (OR,46.712;95%CI,13.067－166.987),placentalprotrusionsign (OR,22.787;95% CI,4.595－113),andintroplacentalT2dark band(OR,14.757;95%CI,7.149－30.461)indicatedhighriskwithmassivepostpartumhemorrhage.Myometrialthinningorlocalized interruption,unevenplacentalsignal,abnormalbloodvesselsbelowtheplacenta,abundantbloodvesselsinloweruterusandcervix, cervicalshorteningandothersignsfortheevaluationofseverepostpartumhemorrhagewerealsostatisticallysignificant.Conclusion MRIcanpredictmostoftheseverepostpartumhemorrhagebeforesurgeryandisveryhelpfultoimprovethepatientprognosis.

The outbreak of COVID-19 has spread quickly across 114 countries/territories/areas in six continents worldwide and has been announced as a pandemic by WHO. This study analyzed global COVID-19 epidemiological trends, examined impact of the pandemic on global health security, diplomacy, and social environment in China, and provided short- and long-term strategic policy recommendations for China’s subsequent preparedness and responses.