Suspected invasive placenta: evaluation with magnetic resonance imaging.

PURPOSE: To determine the utility of magnetic resonance imaging (MRI) in diagnosing invasive placenta (IP). MATERIALS AND METHODS: MRI findings in 32 women with suspected IP were evaluated independently by four readers. Interobserver agreement was calculated with kappa (κ) statistics. Associations between MRI findings and IP were assessed by univariate and multivariate analyses. Sensitivity, specificity and accuracy of MRI for the diagnosis of IP were estimated. RESULTS: Sixteen women (16/32; 50%) had confirmed IP. Interobserver correlation for the diagnosis of IP was fair (κ = 0.40). Univariate analysis revealed that thinning or focal defect of the uteroplacental interface (P < 0.0001) was the most discriminating MRI variable in the differentiation between normal and IP. Overall sensitivity and specificity of MRI for the diagnosis of IP were 84% [95% CI: 75-94%] and 80% [95% CI: 66-93%], respectively. Thinning or focal defect of the uteroplacental interface was the most accurate finding (88%) in the diagnosis of IP. Multivariate analysis revealed that thinning or focal defect of the uteroplacental interface was the single independent predictor of IP (P = 0.0006; OR = 64.99). CONCLUSION: MR imaging has 84% sensitivity [95% CI: 75-94%] and 80% specificity [95% CI: 66-93%] for the diagnosis of IP. Thinning or focal defect of the uteroplacental interface is the most discriminating independent MR variable in differentiating between normal placenta and IP. KEY POINTS: MR imaging has acceptable degrees of accuracy to diagnose invasive placenta. Focal uteroplacental interface defect is the best finding to diagnose invasive placenta. Focal uteroplacental interface defect is the single independent predictor of invasive placenta.

Placental vascularity and resorption delay after conservative management of invasive placenta: MR imaging evaluation.

OBJECTIVES: To assess the potential of magnetic resonance (MR) imaging in evaluating placental vascularity and predicting placental resorption delay after conservative management of invasive placenta. METHODS: MR examinations of 23 women with conservative management of invasive placenta were reviewed. Twelve women had pelvic embolisation because of postpartum haemorrhage (Group 1) and 11 had no embolisation (Group 2). Comparisons between the two groups were made with respect to the delay for complete placental resorption at follow-up MR imaging and degree of placental vascularity 24 h after delivery on early (30s) and late (180 s) phase of dynamic gadolinium chelate-enhanced MR imaging. RESULTS: The median delay for complete placental resorption in the cohort study was 21.1 weeks (range, 1-111 weeks). In Group 1, the median delay for complete placental resorption was shorter than in Group 2 (17 vs 32 weeks) (P = 0.036). Decreased placental vascularity on the early phase was observed in Group 1 by comparison with Group 2 (P = 0.003). Significant correlation was found between the degree of vascularity on early phase of dynamic MR imaging and the delay for complete placental resorption (r = 0.693; P < 0.001). CONCLUSIONS: MR imaging provides useful information after conservative management of invasive placenta and may help predict delay for complete placental resorption.