title: MRI of placenta percreta: differentiation from other entities of placental adhesive disorder.
abstract: OBJECTIVE
  To retrospectively review the MRI findings of placenta percreta and identify those helpful for differentiation from non-placenta percreta.
  
  
  METHODS
  The MRI images of 21 patients with a preliminary diagnosis of placental adhesive disorder scanned between 2005 and 2014 were evaluated. Radiologists blinded to the final diagnosis evaluated six previously described MRI findings of placenta adhesive disorder. The sensitivity, specificity, accuracy, negative predictive value (NPV), and positive predictive value (PPV) of MRI for the diagnosis of placenta percreta were also calculated.
  
  
  RESULTS
  The study included 12 cases of placenta percreta and 9 cases of non-placenta percreta. Invasion of placental tissue outside the uterus was found only in placenta percreta (p = 0.045; sensitivity 41.7 %; specificity 100 %). All placenta percreta cases also had a moderate to marked degree of heterogeneous placental signal intensity (p = 0.063; sensitivity 100 %; specificity 33.3 %). The size of the dark bands on T2-weighted imaging, and the presence of disorganized intra-placental vessels, showed no statistically significant difference between placenta percreta and non-placenta percreta. The sensitivity, specificity, NPV, PPV, and accuracy of MRI for detection of placenta percreta were 91.7, 44, 80, 68, and 71.4 %, respectively.
  
  
  CONCLUSIONS
  MRI is recommended for the evaluation of placenta percreta, with the most specific signs including the invasion of placental tissue outside the uterus on B-FFE sequences, and consideration of the degree of placental signal heterogeneity. The size of the T2 dark band alone, or bizarre disorganized intra-placental vessels, did not correlate with the severity of invasion.
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand. thiravit.mahidol@gmail.com.
authors.forename: Shanigarn
authors.initials: S
authors.lastname: Thiravit
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
authors.forename: Sukanya
authors.initials: S
authors.lastname: Lapatikarn
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
authors.forename: Kobkun
authors.initials: K
authors.lastname: Muangsomboon
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
authors.forename: Voraparee
authors.initials: V
authors.lastname: Suvannarerg
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
authors.forename: Phakphoom
authors.initials: P
authors.lastname: Thiravit
authors.affiliation: Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
authors.forename: Pornpim
authors.initials: P
authors.lastname: Korpraphong
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010921:Placenta Accreta / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
keywords: MRI; Placenta accreta; Placenta percreta; Placental adhesive disorder