Fetal MRI—does it make a difference?

Abstract

Ultrasound is the primary method used for prenatal diagnosis of fetal structural abnormality. However, fetal magnetic resonance imaging (MRI) is increasingly available. This study compares fetal MRI findings with prenatal sonographic images and assesses the benefit of such additional imaging. This was a retrospective survey of cases in a London teaching hospital, where fetal MRI was performed. Sonographic and MRI findings were compared, and any additional value from MRI assessed. Twenty-one MRIs were performed between 21 and 34 weeks’ gestation, 12 for suspected cerebral abnormalities. Other indications included cranial and cervical masses, hemivertebrae, cystic adenomatoid malformation, abdominal masses, cloacal exstrophy and sacro-coccygeal teratoma. In nine of the 12 cases with cerebral abnormality, the MRI appearances agreed with sonographic findings. One pregnancy was continued after MRI excluded the likelihood of lissencephaly. Two pregnancies where a Dandy-Walker malformation was excluded underwent termination for other abnormalities. All but one of the extra-cerebral abnormalities were confirmed on MRI, the exception being an abdominal cyst which resolved spontaneously (confirmed on ultrasound). In one case, MRI gave additional information thus influencing pregnancy management.