Objective To analyze the radiological features of idiopathic pediatric meningiomas and explore their relationships with pathological grading,misdiagnoses,and blood loss during surgery.Methods We retrospectively reviewed 29 cases of pathologically confirmed pediatric meningiomas with pre-operative magnetic resonance imaging in Beijing Tiantan Hospital from November 2014 to July 2018.We assessed the imaging features to explore their relationships with pathological grading,misdiagnoses,and blood

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... ss during surgery. Results Among the 29 cases,7 intraparenchymal meningiomas,5 extraparenchymal meningiomas,4 ventricular meningiomas,and 1 transcranial meningioma were misdiagnosed.Tumor location was significantly associated with possibility of misdiagnoses(P=0.021),and intraparenchymal tumors were most likely to be misdiagnosed.Twelve patients had positive dural tail sign,and 4 of them were misdiagnosed;16 patients did not have dural tail sign,and 12 of them were misdiagnosed.Fisher exact test showed that positive dural tail sign was associated with decreased possibility of misdiagnoses(one-sided P=0.034).Univariable regression analysis showed that the feature of tumor surrounding arteries or interfering with veins(P=0.020)and the tumor maximum diameter(P=0.001)had positively linear relationships with blood loss volume during surgery.Combining these two variables,the multivariable regression model showed better fitting performance($R_{ad}^2$=0.468).Conclusions Pediatric meningiomas are extremely rare,with scarce radiological characteristics.They are hard to diagnose,and the intraparenchymal meningiomas are very likely to be misdiagnosed and therefore should be treated with extra caution.Among all the radiological features,tumor surrounding arteries or interfering with veins and tumor maximum diameter were associated with increased blood loss during surgery.