Vol.:(0123456789) 1 3 Abdominal Radiology https://doi.org/10.1007/s00261-018-1882-8 PELVIS Prenatal planning of placenta previa: diagnostic accuracy of a novel MRI‑based prediction model for placenta accreta spectrum (PAS) and clinical outcome Andrea Delli Pizzi 1  · Alessandra Tavoletta 2  · Roberta Narciso 2  · Domenico Mastrodicasa 3  · Stefano Trebeschi 4  · Claudio Celentano 5  · Jacopo Mastracchio 6  · Roberta Cianci 2  · Barbara Seccia 2  · Luisa Marrone 6  · Marco Liberati 6  · Antonio Rafaele Cotroneo 1,2  · Massimo Caulo 1,2  · Rafaella Basilico 2 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract Purpose To investigate the diagnostic accuracy of MRI for placenta accreta spectrum (PAS) and clinical outcome prediction in women with placenta previa, using a novel MRI-based predictive model. Methods Thirty-eight placental MRI exams performed on a 1.5T scanner were retrospectively reviewed by two radiolo- gists in consensus. The presence of T2 dark bands, myometrial thinning, abnormal vascularity, uterine bulging, placental heterogeneity, placental protrusion sign, placental recess, and percretism signs was scored using a 5-point scale. Pathol- ogy and clinical intrapartum fndings were the standard of reference for PAS, while intrapartum/peripartum bleeding and emergency hysterectomy defned the clinical outcome. Receiver-operating characteristic (ROC) analysis and discriminant function analysis were performed to test the predictive power of MRI fndings for both PAS and clinical outcome prediction. Results Abnormal vascularity and percretism signs were the two most predictive MRI features of PAS. The area under the curve (AUC) of the predictive function was 0.833 (cutof 0.39, 67% sensitivity, 100% specifcity, p = 0.001). Percretism signs and myometrial thinning were the two most predictive MRI features of poor outcome. AUC of the predictive function was 0.971 (cutof − 0.55, 100% sensitivity, 77% specifcity, p < 0.001). Conclusion The diagnostic accuracy of MRI, especially considering the combination of the most predictive MRI fndings, is higher when the target of the prediction is the clinical outcome rather than the PAS. Keywords Magnetic resonance · Placenta accreta spectrum (PAS) · Placenta previa · Placental invasion · Intrapartum bleeding · Clinical outcome Introduction Placenta accreta spectrum (PAS) is the general term applied to abnormal adherence of the placental trophoblast to the uterine placenta. The spectrum includes the attachment of the placenta to myometrium without intervening decidua (placenta accreta), the invasion of the myometrium (pla- centa increta), and the infltration of the surrounding organs through the uterine serosa (placenta percreta) [1]. Previ- ous cesarean section and placenta previa are the two most important risk factors [2]. Pregnancies with invasive pla- centa are more likely to have a preterm delivery and develop potentially fatal (7% cases) massive bleeding caused by the abnormal invasion of the uterus by the placenta [3, 4]. More in detail, placental implantation abnormalities, including placenta previa and placenta accreta, can have catastrophic * Andrea Delli Pizzi andreadellipizzi@gmail.com 1 ITAB Institute of Advanced Biomedical Technologies, “G. d’Annunzio” University, Via Luigi Polacchi 11, 66100 Chieti, Italy 2 Department of Neuroscience, Imaging and Clinical Sciences, “G. d’Annunzio” University, Chieti, Italy 3 Department of Radiology, Stanford University School of Medicine, 300 Pasteur Dr, S-072, Stanford, CA 94305-5105, USA 4 Department of Radiology, Netherlands Cancer Institute, Amsterdam, The Netherlands 5 Department of Medicine and Ageing Sciences, G. d’Annunzio University of Chieti-Pescara, Chieti, Italy 6 Department of Obstetrics and Gynaecology, G. d’Annunzio University of Chieti-Pescara, Chieti, Italy