The MRI features of placental adhesion disorder and their diagnostic significance: systematic review

Aim To identify the most frequently used MRI features in the diagnosis of placenta adhesion disorder (PAD) in the antenatal period and their significance. Materials and methods The online databases Medline via PubMed and Ovid, Google Scholar, and Scopus were searched using the keywords and subject headings MRI*, magnetic resonance imaging*, prenatal diagnosis and placenta accreta*, morbidly adherent placenta* or placenta. Cases where MRI was carried out at/after 20 weeks gestation with detailed information available in relation to criteria and sequences used were included in the review. Exclusion criteria were case report study and studies that used intravenous contrast agents. Information regards sensitivity and specificity for each feature was taken, or calculated where possible, from the papers. Any new features were identified. The overall contribution of each feature to the diagnostic process was noted. Results Six hundred and fourteen potentially relevant articles were identified of which only 11 met the inclusion criteria. The commonest MRI criteria used were T2 dark intraplacental bands, heterogeneity of placenta, abnormal uterine bulging, and disruption of the uteroplacental zone. A newly described criterion is disorganised vasculature of placenta. MRI sensitivity and specificity varied between 75–100% and 65–100% respectively. Conclusion MRI diagnosis of PAD relies on unstandardised criteria of diagnosis that enable systematic image interpretation of invasion status in all studies and enable the reproducibility. However, it is still has a high diagnostic accuracy and frequently aids in surgical planning, emphasising its value in supporting ultrasound. Most studies are of a small sample size. Additional multicentre studies are recommended to enhance the generalisability of the findings and asses the value of the newly described criteria.