The comparison of MRI and Ultrasound in prenatal identification of invasive placentation: a meta-analysis based on 20 parallel control studies

Background: Many previous studies have investigated the Magnetic resonance imaging (MRI) and Ultrasound (US)’s efficiencies in invasive placentation. However, their results were not incomplete agreement. The aim of this research was using meta-analysis method by pooling parallel control studies to compare the MRI and US’s efficiencies in invasive placentation. Methods: Sensitivity and 95% confidence interval (CI), specificity and 95% CI, positive likelihood ratios (LR+) and 95% CI, negative Likelihood Ratios (LR-) and 95% CI, diagnostic odds ratio (DOR) and 95% CI, area under curve (AUC) and 95% CI, summary receiver operating characteristic (SROC) of both US and MRI were calculated. Results: This paper found that the sensitivity of MRI for diagnosis of placenta accreta defects was 85%, with a specificity of 88%. The sensitivity and specificity of US were 86% and 92% respectively, while the sensitivity of color Doppler US was 84% with a specificity of 91%. Conventional dichotomous and continuous data meta-analysis methods did not find any evidence that the relevant indexes of MRI and US were significant different. Conclusion: Considering on the economy, safety, non-invasive and time-saving of US, and no different between US and MRI on diagnostic accuracies, this study suggests that US still remains the preferred choice for diagnosis of placenta accreta. Meantime, MRI can be a complementary to US because it can reveal signs which are invisible by US.