Clinical value of MRI in the diagnosis of placental implantation / 中国基层医药

ABSTRACT

Objective To determine imaging features that may help predict the presence of placenta accreta , placenta increta or placenta percreta on prenatal MRI scanning in order to identify the most diagnostic findings . Methods The prenatal MRI scan data of placenta accreta,placenta increta or placenta percreta (placenta implantation group,n＝15) and normal placenta (placenta normal group,n＝15) diagnosed and treated by surgical pathology from January 2010 to December 2017 in the Peopleˊs Hospital of Huadu District were retrospectively analyzed.Two expert MRI doctors were blinded to the patientsˊtrue diagnosis and were asked to score a total of 10 MRI features of the placenta and adjacent structures.The interrater reliability was assessed using kappa statistics.The features with a moderate kappa statistic or better ( kappa ＞0.40 ) were then compared with the true diagnosis for each observer. Results Eight of the scored features had an interobserver reliability of kappa ＞0.40placenta previa (κ＝0.89);abnormal uterine bulging(κ＝0.57);intraplacental hemorrhage (κ＝0.45);the presence of dark intraplacental bands on T2 W imaging( κ＝0.76); flow －empty blood vessels in placenta ( κ＝0.67); border on placenta and uterus blurring(κ＝0.63);heterogeneity of signal intensity on T 2 －weighted( T2 W) imaging(κ＝0.53);and continuity of myometrium was interrupted ( κ＝0.64).Using Fisherˊs two －sided exact test, there were statistically significant differences between the proportion of patients with placental invasion and those without placental invasion for three of the featuresabnormal uterine bulging ( P＝0.015,P＝0.011);heterogeneity of T2 W imaging signal intensity ( P＝0.006,P＝0.013);and presence of dark intraplacental bands on T 2 W imaging(P＝0.032,P＝0.010).Conclusion MRI can be a useful adjunct to ultrasound in diagnosing placenta accreta prenatally.Three features that are seen on MRI in patients with placental invasion appear to be useful for diagnosis uterine bulging; heterogeneous signal intensity within the placenta;and the presence of dark intraplacental bands on T 2 W imaging.