Ultrasound features versus magnetic resonance imaging features for diagnosis of placenta accreta ‎spectrum

ABSTRACT
Background. Prenatal diagnosis of placenta accreta spectrum (PAS) can minimize maternal morbidity and mortality. This study aims to compare the accuracy of trans-abdominal ultrasound with color and 3D power Doppler versus magnetic resonance imaging (MRI) to diagnose PAS.
Methods. This study included seventy-five pregnant women with placenta previa. They underwent grey-scale trans-abdominal ultrasound with color and 3D power Doppler and non-contrast MRI to confirm placenta previa and detect any suggestive features of placental invasion. All enrolled patients were divided into two groups based on the intraoperative assessment of placental adherence. Group 1 included cases with adherent placenta previa (n=55), and Group 2 included non-adherent placenta previa cases (n=20).
Results. The best ultrasonographic feature to diagnose PAS was the presence of intraplacental lacunae with turbulent blood flow by color Doppler, with a sensitivity of 96.36%, specificity of 100%, positive predictive value of 100%, negative predictive value of 90.91%, values, and accuracy of 97.33%. The best MRI feature to diagnose PAS was the presence of dark intraplacental bands on T2-weighted images, with a sensitivity of 92.73%, specificity of 80%, positive predictive value of 92.73%, negative predictive value of 80%, and accuracy of 89.33%. However, inter-observer and intra-observer reliability were not evaluated.
Conclusions. Both ultrasound with Doppler and MRI offer high sensitivity, specificity, positive and negative predictive values, and accuracy for diagnosing PAS in high-risk women. We suggest using MRI when ultrasound is inconclusive.