[Study on the diagnostic value of fetal magnetic resonance imaging of external ear abnormalities]

Objective: To investigate the diagnostic value of fetal MRI in external ear abnormalities. Methods: 28 fetuses with suspected ear abnormalities based on ultrasound and MRI in Beijing Obstetrics and Gynecology Hospital, Capital Medical University from August 2019 to February 2024 were enrolled retrospectively. The morphology of fetal auricle and external auditory canal were observed to determine the types of external ear abnormalities. The results of postpartum physical examination were taken as the gold standard, paired χ² test and kappa test were used with SPSS 21.0 software to compare the difference and consistency of fetal MRI and ultrasound in diagnosis of external ear abnormalities. Results: 22 cases (31 ears) of microtia were found, of which 30 ears were detected by MRI (sensitivity 96.8%, specificity 100%, accuracy 98.2%) and 28 ears were detected by ultrasound (sensitivity 87.1%, specificity 96.0%, accuracy 91.1%). The detection rates of the two methods were higher in MRI, but there was no statistically significant difference between MRI and ultrasound in diagnosis of microtia (P=0.688), and the results of the two examinations were consistent (kappa=0.786, P<0.001). 24 ears of external auditory canal atresia were all correctly diagnosed by MRI. However, ultrasound could not detect any external auditory canal atresia. Conclusion: The diagnostic ability of MRI for fetal external ear abnormalities was similar to that of ultrasound, and it showed obvious advantages in the diagnosis of external ear canal atresia.