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

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.

Debunking 20th century myths and legends about the diagnosis of placenta accreta spectrum

“…The main MRI features of accreta placentation include abnormal uterine bulging, dark intraplacental bands on T2-weighted imaging, heterogeneous signal intensity within the placenta and disruption of the uteroplacental zone [40][41][42][43][44][45][46][47][48] . Recent data suggest that the finding of a placental budge on MRI has the highest sensitivity for the diagnosis of severe PAS 43 .…”

Texture analysis of dark intraplacental bands on T2WI in the evaluation of placenta accreta spectrum disorders: a feasibility study

“…This study had two main ndings. Firstly, the interobserver agreement of texture analysis for the diagnosis of PAS disorders was substantial, which was a little higher than that of MRI [9].Secondly, although interobserver agreement of texture analysis and MRI for the diagnosis of PAS disorders was similar, the AUC, sensitivity and speci city of texture analysis were perfect and higher than previously reported MRI ndings [9,10].…”

“…It is therefore crucial for radiologists to be involved in the multidisciplinary team and to provide standardized diagnostic assessment of PAS disorders [8]. Ultrasonography (US) had a lower diagnostic accuracy in detecting PAS disorders than MRI, which had a sensitivity 66%, speci city 71% and accuracy 68% [9,10]. Even though US is the frontline imaging modality for the evaluation of PAS disorders [11], MRI is used as a problem-solving tool for equivocal sonographic ndings or suspicion of posterior/lateral placental extension [12][13][14].…”

Prenatal diagnosis of placenta accreta spectrum

“…Table 4 summarizes these findings. A more recent study reported lower accuracy of MRI than previously reported, with a sensitivity and specificity of 66% and 71% for PAS and 85 and 79% for percreta, respectively [68 ▪ ].…”