Evaluation of the Diagnostic Accuracy of Prenatal MRI in Predicting Placenta Accreta Spectrum (PAS) and Clinical Outcomes in Cases with Placenta Previa

INTRODUCTION: The purpose of this study is to investigate the predictive value of magnetic resonance imaging (MRI) parameters in predicting placenta accreta spectrum (PAS) and clinical outcomes of patients with placenta previa. METHODS: A total of 56 prenatal placental MRI examinations acquired via 1.5 and 3 Tesla scanners were retrospectively examined by 2 radiologists in consensus. Presence of T2 dark band, thinning of myometrium, abnormal vascularization, uterine bulging, heterogeneous placenta, placental protrusion, placenta recess and percretism findings were evaluated. While pathology and clinical intrapartum findings constituted the reference standard for placenta accreta spectrum (PAS), intrapartum/peripartum bleeding over 1000 mL and emergency hysterectomy were regarded as poor clinical outcomes. The values of MRI findings in predicting both PAS and clinical outcomes were analyzed. RESULTS: Age, platelet (PLT) value and gestational age were similar in patients with both groups. Signs of percretism had the best diagnostic test performance in predicting clinical worsening, followed by intraplacental abnormal vascularization and placental recession (respectively 80.6%, 76.4%, 73.6%). The most valuable finding in predicting PAS was percretism sign, placental recess, and myometrial thinning (respectively 85.0%, 81.3%, 79.4%). DISCUSSION AND CONCLUSION: Percretism and intraplacental abnormal vascularization are highly predictive of a possible poor clinical outcome.