| 【Abstract】Objective：To assess the value of MRI in the diagnosis of placenta previa as well as accompanying placenta accreta.Methods：The clinical and imaging materials of 25 pregnant patients with placenta previa were included in this study,the age ranged from 21～43y (mean,29.4±6.2y),the gestational age of the fetuses at the time of MRI ranged from 21～38w (mean,32.9±4.0w).All patients underwent MR and ultrasonography (US) before delivery.Taking pathology and the final clinical diagnosis during delivery as gold standard,the value of these two imaging modalities were compared and analyzed.Results：Among the 25 pregnant women with placenta previa,there were central complete type (19 cases),partial type (3 cases) and marginal type (3 cases).MRI and US correctly diagnosed 20 cases and 18 cases respectively,with no significant statistic difference (P＞0.05).The sensitivity and specificity of MRI and US for accompanying placenta accreta was 71.4%,66.7% and 72.7%,69.2%,respectively;the negative predictive value (NPV) and positive predictive value (PPV) was 76.9%,66.7% and 66.7%,69.2%,respectively.On MRI,the placenta accreta demonstrated partial loss of deciduum,focal thinness or absence of myometrium,nodular interface between placenta and uterus,heterogeneous signal intensities within placenta,bands of hypo intensities within placenta on T2WI,loss or diminish of the inter space between placenta and bladder.Conclusion：MRI and US play an important role in the diagnosis of placenta previa and accompanying placenta accreta,they are complementary |
