Magnetic Resonance Imaging Findings of Placenta Accreta Spectrum Disorder: A Pictorial Review.

Abstract: Magnetic resonance imaging (MRI) is used for diagnosing placenta accreta spectrum disorders (PASDs) because of its advanced soft-tissue contrast and spatial resolution capabilities, offering better contrast, improved spatial resolution, and a wider field of view compared with ultrasound. Using a 1.5-Tesla MRI protocol with multiple sequences, MRI can detect indicative signs of PASD such as placental signal heterogeneity, interruption of the myometrium-placenta interface, and abnormal vascularization. Specific sequences such as T2 SSFSE, FIESTA, and T1-weighted and diffusion-weighted imaging are used to assess placental attachment, myometrial invasion, and intraplacental hemorrhages. Significant MRI findings include thick low-signal T2 intraplacental bands, invasions into the cervix or bladder, and abnormal periplacental vascularity. MRI complements ultrasound and is crucial for the prenatal diagnosis of PASD, aiding in treatment planning and patient management, thereby reducing the associated fetal and maternal morbidity and mortality. The objective of this pictorial review was to outline the placental MRI technique and review the main imaging findings in placental MRI for PASD. This review encompasses anonymized patient images obtained following written consent.