| [Objective]To compare placenta image clarity of the two kind of fast sequences(SSFSE and FIESTA) in the prenatal examine, explore the placenta relatively ideal fast sequence scan, provide more high-quality image for diagnosis. Retrospective analysis of34cases of placental imaging signs, compare analysis MRI imaging findings of normal placenta and placental implantation, The purpose of this study was to explore diagnosis value of placenta invasion by MRI, provided reliable basis for clinical prenatal diagnosis and treatment.[Materials and Methods]From January2009through March2013, we reviewed34pregnant women who suspected abnormal placenta or fetus by ultrasound at our hospital, and then underwent prenatal MRI examination.21patients underwent both SSFSE and FIESTA scanning from34cases, those recorded SAR values.Comparing two kinds of scanning methods of placenta image resolution and SAR values, carried on the statistical tests,, respectively.34patients divided into2groups which compare analysis of prenatal MRI imaging manifestations.19pregnant women with ultrasound findings suspicious for placental invasion were case group,15pregnant women with ultrasound findings suspicious for fetal dysplasia were control group. Analysis of each image signs show rate.Findings at MRI were compared with the final diagnosis,which was established with clinical findings at delivery and pathologic examination of specimens. Correlation analysis of MR with surgical pathology results. Computing the sensitivity,specificity and youden index of the MRI diagnosis placenta invasion. Computing the sensitivity,specificity and youden index of the MRI diagnosis placenta placenta accreta,increta,pecreta.[Results]1. SSFSE and FIESTA sequence images of fine rate were71%and42%, respectively.Compare SSFSE and FIESTA sequence, P<0.05, the difference was statistically significant.The SAR values of SSFSE and FIESTA sequence were2.60±0.22and2.81±0.09, P<0.05, the difference was statistically significant.2. Direct signs of MRI in the diagnosis of placenta increta overall display rate: Uterus belt change (fuzzy, interruption) were50.00%and18.75%. Myometrium change (slightly high signal placenta tissue) was18.75%, Uterine serosa layer change (fuzzy, interrupt, slightly high signal placenta tissue) were31.25%,12.50%and31.25%. Bladder serosa layer interruption of display at a rate of12.50%. Compare uterus belt fuzzy and uterine serosa layer fuzzy between the case group and control group respectively, P>0.05, no statistically difference. Enhanced scanning of uterus belt interruption, myometrium change (slightly high signal placenta tissue), uterine serosa layer change (interrupt, slightly high signal placenta tissue) display rate were increase:31.25%,31.25%,31.25%,31.25%. The display rate of grading diagnosis (uterus belt interruption,myometrium see slightly high signal shadow, uterine serosa layer disruption, uterine serosa layer see slightly high signal shadow, bladder serosa layer interrupt) were respectively14.29%,20.00%,50.00%,25.00%and50.00%.3. Indirect MRI signs:low-signal-intensity bands on T2-weighted imaging, placenta outward bulging, abnormal placental vascularity, lower uterine bulging, placenta heterogeneous,uterine wall thinning under the placenta.The disply rate were68.75%,43.75%,31.25%,37.50%,68.75%,62.50%,respectively.Compare the case group and control group of MRI signs respectively for statistics analysis: low-signal-intensity bands on T2-weighted imaging, placenta outward bulging, abnormal placental vascularity,lower uterine bulging, P<0.05,with statistical difference; placenta heterogeneous and uterine wall thinning under the placenta, P>0.05, no statistically difference.4. The volume of low-signal-intensity in placenta accreta,increta,pecreta were:11.28-2.31cm3,16.35-3.56cm3,20.27-3.33cm3, P<0.05, the difference being statistically significant.5. The pathology and surgical findings were used as the reference standard to establish concordance with the MRI findings(R=0.732, P<0.05). MRI diagnosis of placenta invasion revealed87.50%sensitivity,88.89%specificity,0.76youden index. MRI diagnosis of placenta accreta revealed25.00%sensitivity,60.00%specificity,0.15youden index. MRI diagnosis of placenta increta revealed44.45%sensitivity,90.00%specificity,0.34youden index. MRI diagnosis of placenta pecreta revealed100.00%sensitivity,93.75%specificity,0.94youden index.[Conclusion]1.Compare the two quick sequence:SSFSE is more ideal than FIESTA sequence in placenta images. The SAR value of SSFSE sequence is lower. But SSFSE sequence can not replace the FIESTA,the two joint apply for placental blood vessels.2. The overall display rate of direct signs in prenatal invasion is low,including uterus belt interruption,myometrium see slightly high signal shadow, uterine serosa layer disruption, uterine serosa layer see slightly high signal shadow, bladder serosa layer interrupt. The display rate of uterus belt interruption is minimum in grading diagnosis.Uterine serosa layer disruption and bladder serosa layer interrupt showed the highest display rate in grading diagnosis. Enhanced scan can improve the detection rate of direct signs.3. The indirect signs of low-signal-intensity bands show the highest rate.The volume size of low-signal-intensity bands correlation with grading diagnosis.4. These indirect signs have value to the diagnosis of placenta invasion,including placenta outward bulging, abnormal placental vascularity, lower uterine bulging. Placenta heterogeneous and uterine wall thinning under the placenta can not as a diagnostic standard.5. The overall display rate of indirect signs is higher than direct signs, but indirect signs fail to make classification diagnosis of placenta invasion. MRI direct signs used as the classification diagnosis of placenta invasion. So prenatal MRI diagnosis requires combining the direct signs and indirect signs.6.Prenatal MRI diagnosis associate with surgical pathology diagnosis, MRI can be used as the important prenatal imaging examination method of placenta invasion.7. The sensitivity, specific degrees and accuracy is higher in MRI diagnose placenta invasion. The accuracy of grading diagnosis, placenta pecreta> placenta increta>placenta accreta, Placenta accreta is easy misdiagnosis with placenta increta or normal implacentation. |
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