Placental Evaluation with Magnetic Resonance Imaging

Abstract

• Ultrasonography is the primary screening modality for the identification of abnormal placentation, but magnetic resonance (MR) imaging is a complementary imaging modality that is useful when ultrasonography is inconclusive. • As most patients referred for placental evaluation with MR imaging have suspicious findings on ultrasonography, the pretest probability for abnormalities on MR imaging is high. • Imaging features useful for the diagnosis of abnormal placentation include placental lobulation with uterine contour bulge, interruption of the inner low signal-intensity myometrial layer, and placental heterogeneity resulting from dark intraplacental bands and abnormal vascularity on T2-weighted imaging. • Reliably differentiating placenta accreta from increta and placenta increta from percreta is difficult, and often not possible. • Antenatal diagnosis of placental abnormalities is critical in aiding the referring clinician to avoid or mitigate potential complications. Keywords Placenta, Accreta, Increta, Percreta, Previa, Magnetic resonance