The Diagnostic Value Of Prenatal MRI Signs In Placenta Implantation Abnormality

Objective:To explore the value of magnetic resonance imaging(MRI)signs in placenta implantation and its classification,to analyze the main imaging signs of placenta implantation,and to explore the prenatal diagnostic efficacy of each imaging sign on MR for placenta implantation,as well as the value of combined application of multiple signs.Materials and methods:The prenatal MRI findings,clinical and pathological data of 54 patients from Jan.2017 to Oct.2018 who were suspected for clinic or ultrasound placenta previa,Analysis of abnormal signs of prenatal MRI.MRI accuracy to evaluate the presence of PIA was assessed on the basis of the occurrence of the following abnormal MRI signs:?intraplacental dark bands;?focal interruption of myometrial border;?Interruption of signal in uterine myometrium;?intraplacental abnormal vascularity;?Inferior uterine bulging;?tenting of the bladder and/or direct isualization of adjacent tissues invasion?Imaging results were classified as suggestive or not of PIA using histological data as standard of reference;two methods of imaging analysis were used represented by the presence of at least one(Method A:presence of at least one abnormal MRI sign in two scanning planes)or two(Method B:presence of at least two abnormal MRI signs in two scanning planes)abnormal MRI signs;the correlation between the presence of each abnormal MRI sign of PIA and the corresponding histological finding was also assessed.Results:The patients were divided into placenta implantation group(31 cases)and placenta-free group(23 cases)according to the gold standard of surgical records and pathological results.There was a good consistency between MRI prenatal diagnosis of placenta implantation and surgical and pathological results(kappa=0.724).MRI is helpful for the classification of placenta implantation,among which penetrating placenta implantation has the highest diagnostic accuracy(Youden:0.75),while the accuracy of placenta implantation and adherent placenta implantation is lower(Yonden:0.50,0.523).Among the abnormal MRI signs,intraplacental dark bands and focal interruption of myometrial border were those highly correlated with histological proof of PIA(0.87);as result,a modifified version of Method B(Method C)was identifified considering as criterion for PIA the combined.The accuracy was higher for Method B(0.87)compared to Method A(0.796).the accuracy of Method C(0.648)was signifificantly lower than Method B(0.87)and Method A(0.796).Conclusions:MRI is a useful imaging technique to assess PIA in patients,MRI can be used as prenatal examination Placenta implantation diagnosis and screening is an important method.MRI can make typing diagnosis on placenta accreta to some extent.Intraplacental dark bands,focal interruption of uterine boundary and Inferior uterine bulging was correlated with histological evidence of PIA.Among all the abnormal MRI signs,method B(at least two abnormal signs)is the best method to diagnose PIA.