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      We appreciate the work of Dr Matsubara and the interest in our research on placenta accreta spectrum disorders (PAS). Thank you for the opportunity to clarify our data and address 2 important points.
      First, the percreta detection rate is not the only consideration when ordering magnetic resonance imaging (MRI). That 7 patients (9%) were correctly upgraded to percreta is only part of the story. In our cohort, MRI incorrectly upgraded 10 cases (13%) to percreta (severe PAS). These patients, if managed differently from PAS, could suffer unnecessary harm from additional procedures or iatrogenic preterm delivery. MRI in these cases, then, could be harmful. Furthermore, in 6 cases (8%), MRI incorrectly confirmed a diagnosis of nonsevere PAS when percreta (severe PAS) was actually present. Here again, MRI was misleading and could result in harm when obstetric and surgical teams are less prepared for the worst-case scenario.
      Given the modest predictive ability and unacceptably high false-negative rate of all imaging modalities for percreta (true for both MRI and ultrasound), we propose that all cases of suspected PAS, not just cases of suspected percreta, be managed as though they may be percreta in centers with experience in managing PAS.
      Second, even if maximizing the detection rate of percreta were the only consideration when ordering an MRI for PAS, available data do not support the conclusion that MRI is more sensitive than ultrasound. Two recent meta-analyses of ultrasound and MRI for the detection of percreta concluded that ultrasound and MRI are equivalent.
      • Pagani G.
      • Cali G.
      • Acharya G.
      • et al.
      Diagnostic accuracy of ultrasound in detecting the severity of abnormally invasive placentation: a systematic review and meta-analysis.
      • Familiari A.
      • Liberati M.
      • Lim P.
      • et al.
      Diagnostic accuracy of magnetic resonance imaging in detecting the severity of abnormal invasive placenta: a systematic review and meta-analysis.
      Moreover, we are not stating that MRI is useless for PAS. Rather, we question whether MRI is useful once a quality ultrasound has been performed. This is relevant in many cases when there is insufficient expertise or resources to perform MRI.
      We wholeheartedly agree with Dr Matsubara that the accurate antenatal diagnosis of PAS is highly desirable. Indeed, we look forward to further research toward this goal. We recognize that our data are not definitive and can be interpreted differently within the context of various settings and management strategies. But we stress that the potential added benefit of MRI should be weighed against the risks of overdiagnosis, underdiagnoses, and a misleading change in diagnosis when it is used as an adjunct to ultrasound.

      References

        • Pagani G.
        • Cali G.
        • Acharya G.
        • et al.
        Diagnostic accuracy of ultrasound in detecting the severity of abnormally invasive placentation: a systematic review and meta-analysis.
        Acta Obstet Gynecol Scand. 2018; 97: 25-37
        • Familiari A.
        • Liberati M.
        • Lim P.
        • et al.
        Diagnostic accuracy of magnetic resonance imaging in detecting the severity of abnormal invasive placenta: a systematic review and meta-analysis.
        Acta Obstet Gynecol Scand. 2018; 97: 507-520

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