Comparative Study Of MRI In The Diagnosis Of Prenatal Placental Accreta And The Efficiency Of Each Rapid Sequence

Objective:1.Diagnosis of prenatal placental accreta by MRI,ultrasound and compare the accuracy of the two methods.2.To analyze the clinical manifestations of prenatal placental accreta MRI and to evaluate the diagnostic value of MRI in typing.3.To compare the efficacy of SSh-TSE and B-FFE sequences in displaying placental accretion signs with MRI rapid scanning technique.Material and Methods:A retrospective analysis of 75 cases of suspected placental implantation in the People’s Hospital of Shaanxi Province from September 2016 to September 2018,with a median age of 33 to 4 years,with a median age of 33 to 4 years,with a median age of 24⁺⁵to 39⁺³ weeks,with an average of 35⁺³weeks;a history of pre-placenta,induced abortion,and a history of drug abortion.It is possible to include one or more high-risk factors such as Qinggong and Hysteromyoma,and can be included in one or more high-risk factors such as the age of the pregnant woman>35 years,and the congenital malformation of the uterus and the quality of the image are not good.Included in the patient’s clinical basic data complete,all-line MRI routine and DWI scan Two-dimensional gray-scale and three-dimensional color Doppler ultrasonography were used to compare the difference between the two methods in the diagnosis of prenatal placental accretion,which was consistent with the gold standard,taking the pathological results and clinical diagnosis as the gold standard,and using statistical method to compare the difference between the two groups in the diagnosis of prenatal placental accretion.The sensitivity of（Se）,specificity（Sp）,positive predictive value（PPV）and negative predictive value（NPV）,false negative rate false positive rate and coincidence rate were calculated and the MRI manifestations of prenatal placental accreta were analyzed.The comparison of SS-TSE and B-FFE sequences in MRI rapid scanning for prenatal placental accreta was performed by statistical method.Diagno-stic efficacy.Results:The sensitivity and specificity of MRI and ultrasound in the diagnosis of placental accreta were 86.3%,77.2%and 86.2%,respectively.90.3%,77.4%,the coincidence rates were 88%and 77.3%,respectively.There was no significant difference between the diagnostic results of MRI and ultrasound and clinical and/or pathological diagnosis,and the coincidence between MRI and gold standard was（κ=0.655,p=0.000）.The coincidence between ultrasound and gold standard was（κ=0.364,p=0.009）.The sensitivity of MRI for diagnosis of adhesive,implantable and penetrating placen-tal accreta was 55.6%,42.9%,100%,respectively.The specificity and specificity were88.9%,100%and 93.3%,respectively.The coincidence rates were 82.2%,91.1%and93.3%,respectively.The signs of prenatal placental accretion in MRI included direct signs:the low signal intensity of the uterine stroma disappeared,the myometrium localized thinned and interrupted（35/44）;Indirect signs included inhomogeneous intraplacental signal（38/44）,multiple circuitous flow-void signal shadows（28/44）,and localized uterine dilation（34/44）.SS-TSE sequence showed intraplacental signal changes and the boundary between placenta and muscular layer was superior to that of B-FFE group,while B-FFE sequence showed that placental inrush into muscular layer was superior to that of SS-TSE group.Among 44 cases of placental accreta confirmed by clinical diagnosis,30 cases（68.2%）had excellent B-FFE images and 14 cases（31.8%）had poor images.There were 20 cases（45.5%）with excellent images and 24 cases（54.5%）with poor images by SSh-TSE sequence.There was a significant difference between B-FFE and SSh-TSE sequences（χ²=4.790,P<0.05）.B-FFE sequence and SSh-TSE sequence showed non-uniform signal to placenta,low signal shadow of intraplacental strip,increased and thickened vascular shadow in placenta,interruption of uterine junction zone and protrusion of placenta into myometrium of uterus.The signs of placental protrusion were 56.8%,54.5%,27.3%,61.3%,65.9%,4.5%and 88.6%,72.7%,38.6%,43.2%,29.5%,respectively.4.5%,the display rate of inhomogeneous placental signal and placental protrusion into the myometrium of uterus were compared between the two sequences.The difference was statistically significant（χ²=11.229,11.66,P<0.05）.Conclusion:1.There was no significant difference between the diagnostic results of MRI,and gold criteria（clinical or pathological results）in prenatal placental accretion.The diagnostic results of MRI and gold criteria were slightly better than those of ultrasound,and there was no significant difference between the diagnostic results of CDFI and gold criteria（clinical or pathological results）.MRI has certain value in the depth and classification of prenatal placental accretion.Therefore,MRI can be used as an important supplement and imaging method for further diagnosis of prenatal placental accretion when ultrasound diagnosis of prenatal placental accretion is not clear.2.The diagnostic value of all kinds of MRI signs is different,and placenta accretion in the third trimester of pregnancy is obviously thinner because of the obvious thinning of myometrium,and some direct signs are difficult to show,but at the same time,when multiple MRI imaging signs appear at the same time,MRI is difficult to diagnose adhesive placental accretion,and its sensitivity and specificity are lower than those of implantable and penetrating placental accretion.3.he In t aspect of image display,the contrast of soft tissue between SS-TSE sequence and B-FFE sequence is better,and the spatial resolution of the latter is higher.In the aspect of image display,SS-TSE sequence is compared with B-FFE sequence.The contrast of soft tissue is better in the former and the spatial resolution of the latter is higher.In practice,the two sequences are often combined to improve the accuracy of diagnosis.