Table 1.
Clinical characteristics and pregnancy outcomes according to PAS status.
Table 2.
Prediction of maternal and neonatal outcomes by US.
Fig 1.
Detection rate of placenta accreta spectrum (PAS) on prenatal ultrasonography (US).
The detection rate of confirmed PAS was significantly higher in PAS-suspected on US group than PAS-unsuspected on US group (39.5% vs 10.9%, p < 0.001). PAS, placenta accreta spectrum; US, ultrasonography.
Table 3.
Prediction of maternal and neonatal outcomes by MRI.
Fig 2.
Detection rate of placenta accreta spectrum (PAS) on prenatal magnetic resonance imaging (MRI).
The rate of confirmed PAS was markedly higher in PAS-suspected on MRI group than in PAS-unsuspected on MRI group (52.6% vs 11.8%, p < 0.001), indicating a significant diagnostic association. PAS, placenta accreta spectrum; MRI, magnetic resonance imaging.
Table 4.
Sensitivity, specificity, PPV, NPV, and accuracy of US and MRI in detecting PAS.
Fig 3.
Final diagnosis of placenta accreta spectrum (PAS).
The final diagnosis was made with a combination of US and MRI. Patients were categorized into three groups based on prenatal imaging results: 1) both US and MRI findings were negative (US = 0, MRI = 0); 2) either US or MRI was positive, but not both (US = 0, MRI = 1 or US = 1, MRI = 0); and 3) both US and MRI were positive (US = 1, MRI = 1). A significant difference was observed between the group with US = 0 and MRI = 0 and the group with US = 1 and MRI = 1 (p < 0.001), as well as between the single-positive group (US = 0 and MRI = 1 or US = 1 and MRI = 0) and the group with US = 1 and MRI = 1 (p < 0.001). A significant linear trend was noted in PAS occurrence across the three diagnostic combinations (p < 0.001), with the highest rate observed in cases positive on both US and MRI. PAS, placenta accreta spectrum; US, ultrasonography; MRI, magnetic resonance imaging.
Fig 4.
Receiver operating characteristic (ROC) curve comparison for placenta accreta spectrum (PAS) diagnosis.
Patients were diagnosed using US-only, MRI-only, and US + MRI models. The ROC curves demonstrate the diagnostic performance of US alone (red), MRI alone (blue), and a combination of US and MRI (green) in detecting PAS. The combined model showed the highest overall diagnostic accuracy, with a greater AUC than each modality alone. Pairwise comparisons demonstrated statistically significant differences between US-only and MRI-only (p = 0.207), MRI-only and US + MRI (p = 0.002), and US-only and US + MRI (p = 0.001) cases. AUC, area under the curve; MRI, magnetic resonance imaging; PAS, placenta accreta spectrum; ROC, receiver operating characteristic; US, ultrasonography.
Table 5.
Prediction of maternal and neonatal outcomes based on US and MRI combination.
Fig 5.
Flowchart comparing the diagnostic concordance between US and MRI.
Patients were classified by prenatal US suspicion and then by MRI suspicion, with each terminal box indicating whether US or MRI were correct relative to the final diagnosis confirmed postnatally. PAS, placenta accreta spectrum; US, ultrasonography; MRI, magnetic resonance imaging.