The Comparative Study And Performance Of MRI Diagnostic Value In Prenatal Placenta Increta

Objective:1.To compare the accuracy of the MRI and ultrasound in the diagnosis of prenatal increta2.To analyze the diagnostic value of MRI on the depth of prenatal placenta increta3.To analyze the MRI manifestations of placenta increta prenatalMaterial and Methods:45 patients who were suspected to suffer from placenta increta were collected in the hospital from February 2013 to January 2015, the patients were aged to 20-40 years old and had 27-39 weeks pregnancy with high risk factors including placenta previa,operating history of uterine( abortion, medicine flow Curettage or uterine fibroids, etc.)and advanced maternal age, without congenital uterine anomaly, respiratory and fetal movement artifacts significantly. All patients with complete clinical data were performed MRI and DWI scan,transabdominal 2D gray-scale and 3D color doppler ultrasound examination. To compare the differences between the two diagnostic methods by statistical method and the consistency with the gold standard,the pathology and intraoperative diagnosis results. In addition, the sensitivity, specificity,positive predictive value, negative predictive value and coincidence rate of placenta accreta examined by two methods were calculated. To analyse the MRI manifestation of prenatal placenta increta.Results:The sensitivity, specificity and coincidence rate of placenta accreta diagnosis by MRI were 75% 、89.7%、84.4% respectively. Moreover, the sensitivity, specificity and coincidence rate of placenta accreta diagnosis by ultrasound were 75% 、65.5%、68.9% respectively. Comparing to clinical and/or pathologic diagnosis, there were no significant difference between MRI and ultrasound diagnosis in pair-wise comparison.The goodness fit of MRI with gold standard was(kappa = 0.656 predominate, p = 0.656),and that of ultrasound with gold standard was(kappa = 0.374 predominate, p = 0.374).The sensitivity, specificity and coincidence rate of adhesive placenta accreta diagnosis by MRI were 55.6%、88.9%、82.2%, respectively. The sensitivity, specificity and coincidence rate of implantable placenta accreta diagnosis by MRI were42.9 % 、100 % 、 91.1 %, respectively. The sensitivity, specificity and coincidence rate of penetrable placenta accreta diagnosis by MRI were 100%、93.3%、93.3%。The symptom of prenatal placenta implantation had direct sign and indirect sign.The direct signs included low signal of uterine stromal layer disappeared, myometrium was limited thinner and suspended, and irregular high signal placenta tissue was appeared in myometrium. Furthermore, the indirect signs had following signs:asymmetrical signal was in placenta, tortuous empty signals were in placenta, lower uterine segment was swelling, cervix was swelling and bladder wall was not smooth.Conclusion:1.MRI and ultrasound diagnosis and clinical and/or pathologic diagnosis for prenatal placenta implantation were no significant difference in statistics, so both of the methods could be important means of diagnosis. Comparing to ultrasound diagnosis,MRI had higher consistency with gold standard. MRI diagnosis had high specificity and research value for the depth of the implanted placenta. As a consequence, MRI could be used as a necessary imageological examination diagnosis for prenatal placenta increta,and ultrasonic preferred as a routine screening.2.The sensitivity and specificity of adhesive placenta accreta were lower than implantable placenta accreta and penetrable placenta accreta diagnosed by MRI, so thediagnosis of adhesive placenta accreta was little difficult.3.The direct signs of late in pregnancy placenta increta displayed diffcult, and the indirect signs could not only be the specific signs, so at least more than two comprehensive analytics signs needed for diagnosis.