AJR:211, September 2018 701 abnormal placenta is strongly attached to the myometrium, it may be diffcult to sepa- rate it from the uterus or any potentially in- volved extrauterine structures, such as the bladder wall, intestine, parametrium, or uter- ine ligaments, increasing the risk of massive intra- or postpartum bleeding, uterine rup- ture, and adjacent organ injury. Invasive pla- centa is the leading cause of peripartum hys- terectomy, performed in up to 64% of such cases [2], and uncontrollable hemorrhage (> 3–5L) may be fatal in up to 7% of patients [3]; when bladder invasion is present, mater- nal and neonatal mortality rates rise to 9.5% and 24%, respectively [4]. Therefore, accu- rate knowledge of placental extension before the delivery allows obstetricians to schedule a multidisciplinary approach with participa- tion of well-trained operating room person- MRI Features Predictive of Invasive Placenta With Extrauterine Spread in High-Risk Gravid Patients: A Prospective Evaluation Charis Bourgioti 1 Konstantina Zafeiropoulou 1 Stavros Fotopoulos 2 Maria Evangelia Nikolaidou 2 Aristeidis Antoniou 1 Chara Tzavara 3 Lia Angela Moulopoulos 1 Bourgioti C, Zafeiropoulou K, Fotopoulos S, et al. 1 Department of Radiology, School of Medicine, National and Kapodistrian University of Athens, Aretaieion Hospital, 76 Vassilisis Sofas Ave, Athens 11528, Greece. Address correspondence to C. Bourgioti (charisbourgioti@yahoo.com). 2 Department of Gynaecology and Obstetrics, REA Maternity Hospital, Athens, Greece. 3 Department of Health, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece. Women’s Imaging • Original Research Supplemental Data Available online at www.ajronline.org. AJR 2018; 211:701–711 0361–803X/18/2113–701 © American Roentgen Ray Society D uring the past decades, there has been an increased incidence of abnormal placentation, mainly attributed to the wide use of ce- sarean section (C-section) and advanced ma- ternal age. Abnormal placental adherence at the level of the internal cervical os, known as placenta previa, is associated with invasive placentation in 9% of women with no history of uterine intervention and in almost 24% of women with a single prior C-section; in pa- tients with multiple (> 3) C-sections, the risk for invasive placenta becomes extremely high (67%) [1]. Prenatal diagnosis of placenta percreta (i.e., a placenta that extends to or beyond the uterine serosa), the most aggressive form of invasive placenta, is an important issue for clinicians for several reasons. Because the Keywords: abnormal placentation, bladder invasion, parametrial invasion, placenta percreta, placenta previa doi.org/10.2214/AJR.17.19303 Received November 19, 2017; accepted after revision February 17, 2018. Based on a presentation at the European Society of Urogenital Radiology 2017 annual meeting, Sopot, Poland. OBJECTIVE. The objective of our study was to evaluate MRI diagnostic ability in pre- dicting invasive placenta with extrauterine spread in high-risk gravid patients. SUBJECTS AND METHODS. Between March 2016 and June 2017, 49 patients (mean age, 35.7 years; mean gestational age, 32.5 weeks) with sonographically confrmed placenta previa underwent dedicated MRI. All MRI examinations were reviewed by two experienced radiologists prospectively. Intraoperative and pathologic fndings were the standard of refer - ence. Kappa values were calculated to assess the agreement between MRI fndings and his- tologic results as well as interrater reliability. ROC curve analysis was used to test the dis- criminative ability of MRI features for invasive placenta with extrauterine spread. Stepwise multiple logistic regression analysis was performed to identify any MRI fndings predictive of invasive placenta and of bladder and parametrial involvement. RESULTS. MRI exhibited signifcant overall accuracy (AUC = 0.77, p = 0.006) in iden- tifying invasive placenta with 100% sensitivity and negative predictive values; it was highly specifc (100%) in identifying placental extension to both bladder and parametrial tissues. Lumpy tapering of the placental edges, intraplacental dark T2 bands, prominent intraplacen- tal vascularity, and serosal hypervascularity were independently associated with an increased risk for invasive placenta. Serosal hypervascularity and vesicouterine space hypervascularity were independent predictors of bladder invasion; abnormal vascularization within the para- metrial fat was signifcant for parametrial invasion. CONCLUSION. MRI is highly accurate in depicting placental extrauterine spread. The presence of abnormal vessels at the uterine serosa was the most important MRI feature for identifying invasive placenta. An abnormal vascular network within the vesicouterine space or parametrium was the most reliable MRI sign for detecting bladder or parametrial involvement. Bourgioti et al. Invasive Placenta With Extrauterine Spread Women’s Imaging Original Research Downloaded from www.ajronline.org by 3.94.110.230 on 01/08/22 from IP address 3.94.110.230. Copyright ARRS. For personal use only; all rights reserved