Comparative study of ultrasonography and magnetic resonance imaging in midline structures of fetal brain

Objective To evaluate the accuracy of ultrasonography(US) and magnetic resonance imaging(MRI) in midline structures of fetal brain.Methods Thirty-two fetuses underwent US and MRI examinatiom.Imagings acquired from US and MRI were analysed,the results were compared with the final outcomes which were obtained after fetal birth or pathological study after induction of labor.Results There were 20 cases found abnormal in prenatal CNS ultrasonography(18 cases involving midline structures).Among these 20 cases,12 cases were normal in MRI and the fetuses were born in full-term without special problem,8 cases were abnormal in MRI and fetal autopsy confirmed their abnormalities.Diagnostic accuracy rate of US was 93.8%,sensitivity was 100%,specificity was 87.5%,positive predictive value was 88.9%,negatvie predictive value was 100%.Diagnostic accuracy rate of MRI was 100%,modifying the US results in 4 cases.Conclusion US and MRI examinations are important in fetal central nervous system.US could be the first line examination,and MRI is an important supplement because of the high diagnostic accuracy,especially in the image study of midline structures of fetal brain.