The morbidly adherent placenta: when and what association of signs can improve MRI diagnosis? Our experience.
Department of Radiological Sciences, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy
Department of Obstetrics and Gynecology, Catholic University of Sacred Heart, Agostino Gemelli Hospital, Rome, Italy
Diagn Interv Radiol ; : -
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Objective: To verify whether combination of specific signs improves MRI accuracy in morbidly adherent placenta (MAP).
Material and Methods: The Institutional Review Board granted permission for this retrospective study and a waiver of informed consent. The presence/absence of MRI findings for MAP were retrospectively evaluated in 27 women. Histopathology was the reference standard, showing MAP in 8/27 and 19/27 normal cases. MRI results were analyzed by 2x2 tables. MRI SS, SP, PPV and NPP were calculated for every single sign; the Fisher exact Test was employed for statistical significance. Two skilled radiologists analyzed MRI findings, resolving discrepancies by consensus, using 3 diagnostic criteria during 3 consecutive sections: a) 1st criterion: at least any one of reported MRI signs indicates MAP and the absence of any sign is normal; b) 2nd criterion: at least 1statistically significant sign (SSS) indicates MAP and no sign or non-SSS is normal; c) 3rd criterion: at least 2 SSS signs indicate MAP and no sign, non-SSS or only 1 SSS is normal. The criteria were compared for diagnostic accuracy by the Exact McNemar test (p < 0.05 significant).
Results: The 1st MRI criterion showed unacceptable rate of FP results (78.9%). Using the 2nd criterion FP results were less high (31.5%), and the Exact McNemar test stated that diagnostic accuracy of the 2nd criterion was significantly higher than the 1st ; the 3rd criterion correctly classified 100% of cases.
Conclusion: Only specific MRI signs can correctly predict MAP at histopathology, especially when associated.