MRI features in foetal microtia

Abstract Background: Atresia of the external auditory canal is positively correlated with the difficulty and success rate of operation after birth. At present, ultrasound screening often obtains images of body position, placenta and amniotic fluid, and the detection rate is low. Moreover, it is unable to evaluate whether the external auditory canal shows atresia. Methods: We retrospectively conducted MRI features of 9 cases those were diagnosed foetal microtia from May. 2019 to Oct. 2020. Results: Nine cases of microtia foetus were analysed: male, five cases; female, four cases; right ear, five cases; left ear, four cases; and degree I, one case (bilateral external auditory canal is shown); degree II, eight cases (affected external auditory canal is not shown, six cases of normal external auditory canal shown, two cases of normal external auditory canal not shown). All parturients underwent amniocentesis full exon gene detection, of which the results were negative. The magnetic resonance imaging (MRI) features of microtia, included abnormal external ear morphology, disappearance of normal structure, mass-like and small piece-like soft tissue shadow and equal signal on T2-weighted (T2W) imaging. The upper and lower diameters were significantly smaller than that of the normal side. The MRI features of external auditory canal atresia included disappearance of T2W linear high signal shadow in the temporal bone scale. Conclusions: Foetal MRI can diagnose microtia and evaluate atresia of the external auditory canal.