Diagnostic Value of Ultrasonography and MR in Antenatal Diagnosis of Placenta Accreta Spectrum

Abstract

The aim of this study was to compare the accuracy of ultrasonography and magnetic resonance imaging (MR) in the antenatal diagnosis of placenta accreta. We also determined the most relevant sonographic and MR features associated with the diagnosis of placenta accreta. In a prospective observational study approved by the Ethical Board of the Radiology Department, 109 pregnant women who were at high risk for Placenta Accreta were enrolled. The placentas of all cases were scanned using both gray-scale and color Doppler transabdominal sonography. MR was performed when sonographic findings were equivocal or inconclusive. The sonographic and MR features were compared with the final pathologic or clinical findings. The sensitivity and specificity were calculated for both sonography and MR. The role of each sonographic and MR feature was calculated by logistic regression. P < 0.05 was considered as the significance level. The sensitivity and specificity of ultrasonography for the diagnosis of Placenta Accreta spectrum were 87% and 85% (P < 0.001), while those of MR were 100% and 42% (P = 0.1), respectively. In ultrasonography, myometrium thickness ≤ 1 mm with a sensitivity of 83% (95 CI: 0.765, 0.927) and loss of retroplacental clear space with a sensitivity of 81% (95 CI: 0.755, 0.920) had the best sensitivity for the detection of the placental invasion. On MR, the heterogeneous signal intensity of placenta and uterine bulging with a sensitivity of 87% (95 CI: 0.698, 1.04) had the best sensitivity. Placenta accreta can be successfully detected prenatally using ultrasound. MR is useful in equivocal cases.