[The MRI analysis of 220 cases of placenta previa complicated with placenta accrete or not]

Objective: To investigate the diagnostic value of MRI for placenta previa complicated with placenta accreta or not. Methods: A total of 220 placenta previa patients were diagnosed by prenatal ultrasound and MRI in The Second Affiliated Hospital of Wenzhou Medical University from May 2014 to May 2017.The MRI images of 220 placenta previa patients suspicious of placenta previa were interpreted by two radiologists who majored on gynecological radiology. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of two radiologists in diagnosis of placenta accreta were calculated respectively. Kappa test were used to verify the consistency between two doctors, as well as their MRI diagnosis and pathological results. The diagnostic value of MRI and pathological were assessed by Chi-square test and receiver operating characteristic (ROC)curve. Results: The 220 patients were all confirmed with placenta previa by surgical pathology.Out of 220, 71 cases were diagnosed as placenta accreta, and 149 cases were diagnosed without placenta accreta. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value with physician A and physician B were 90.1%/84.5%, 88.6%/89.9%, 89.1%/88.2%, 79.0%/80.0% and 95.0%/92.4%, respectively.The consistency between MRI diagnosis and pathological results was excellent in physician A (κ=0.759), and good in physician B (κ=0.734). However, the sensitivity, specificity and accuracy of diagnosis between two physicians had no significant difference (all P>0.05). The area under the curve (AUC) of ROC in physician A and B were 0.858 and 0.847 (P=0.980). Conclusion: MRI is feasible for patients with placenta previa, as the sensitivity, specificity and accuracy of MRI are high in assessing whether placenta previa complicated with placenta accreta or not.