OP19.02: Comparison of diagnostic performance between obstetric ultrasound and magnetic resonance imaging for antenatal diagnosis of placenta accreta spectrum disorders

Abstract Objectives We aimed to assess the performance of ultrasound (US) and magnetic resonance imaging (MRI) signs for antenatal detection of placenta accreta spectrum (PAS) disorders in women with placenta previa (placental edge ≤2 cm from the internal uterine orifice, ≥260/7 weeks’ gestation) with and without a history of previous Caesarean section. Methods Single center prospective observational study. US suspicion of PAS was raised in the presence of obliteration of the hypoechoic space between uterus and placenta, interruption of the hyperechoic uterine-bladder interface and/or turbulent placental lacunae on color Doppler. All MRI studies were blindly evaluated by a single operator. PAS was defined as clinically significant when histopathological diagnosis was associated with at least one of: intrauterine balloon placement, compressive uterine sutures, peripartum hysterectomy, uterine or hypogastric artery ligature, uterine artery embolization. Results A total of 39 women were included: 7/39 had clinically significant PAS. There were 6/18 cases of PAS with anterior placenta: hypoechoic space interruption and placental lacunae were the most sensitive sonographic signs (83%), while abnormal hyperechoic interface was the most specific (83%). On MRI, focal myometrial interruption and T2 intraplacental dark bands showed the best sensitivity (83%), bladder tenting had the best specificity (100%). 1/21 women with posterior placenta had PAS. There was substantial agreement between US and MRI in patients with anterior placenta (κ=0.78). Conclusions US and MRI agreement in antenatal diagnosis of clinically significant PAS was maximal in high-risk women. Placental lacunae on ultrasound scan and T2 intraplacental hypointense bands on MRI should trigger the suspicion of PAS.

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Accuracy and Interobserver Reliability of Magnetic Resonance Imaging for Placenta Accreta Spectrum Disorders

American Journal of Perinatology ◽

10.1055/s-0040-1701196 ◽

2020 ◽

Author(s):

Brett D. Einerson ◽

Christina E. Rodriguez ◽

Robert M. Silver ◽

Meghan A. Donnelly ◽

Anne M. Kennedy ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Predictive Value ◽

Placenta Accreta ◽

Interobserver Reliability ◽

Diagnostic Testing ◽

Kappa Statistics ◽

Resonance Imaging ◽

Mri Findings ◽

Placenta Accreta Spectrum

Abstract Objective This study aims to define the accuracy, predictive value, and interobserver reliability of magnetic resonance imaging (MRI) in the diagnosis of placenta accreta spectrum (PAS) disorders. Study Design Two experienced radiologists independently interpreted the MRI studies of patients with possible PAS from two referral centers. Radiologists were blinded to sonographic and clinical information. We calculated diagnostic testing characteristics and kappa statistics of interobserver reliability for MRI findings of PAS. Results Sixty-eight MRI cases were evaluated. Confirmed PAS and severe PAS were present in 44 (65%) and 20 (29%) cases. For the diagnosis of any PAS, MRI had a sensitivity 66%, specificity 71%, positive predictive value (PPV) 81%, negative predictive value (NPV) 53%, and accuracy 68%. For the diagnosis of severe PAS (percreta), MRI had a sensitivity 85%, specificity 79%, PPV 63%, NPV 93%, and accuracy 81%. The accuracy of individual signs of PAS was lower (44–65%). Interobserver agreement was almost perfect for previa; substantial for myometrial interruptions, PAS, severe PAS, and placental bulging/balling; and moderate to slight for other signs of PAS. Conclusion Although the interobserver reliability of MRI for a diagnosis of PAS is substantial, the accuracy and predictive value are modest and lower than previously reported.

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