Objective: The objective of this study was to compare antepartum ultrasonography and magnetic resonance imaging (MRI) in the diagnosis and exclusion of malformations of the fetal neck, pharynx, skull base and posterior fossa in late pregnancy.
Materials and methods: The study involved 26 women and 27 fetuses with ultrasonographically or clinically suspected abnormalities of the fetal neck, pharynx or central nervous system (CNS). Findings obtained by ultrasound were compared with those obtained by MRI (1.5 T) in the last trimester.
Results: In cases with CNS malformation (n = 19), MRI provided additional information on the anatomy of the foramen magnum and posterior fossa in nine cases (47%). When antepartum ultrasonography indicated malformation of the soft tissues of the neck or pharynx (n = 8), MRI provided additional information on diagnosis or exclusion of the abnormality in six cases (75%). The imaging capacity of the anatomy of the naso-, oro- and hypopharynx, trachea, esophagus and cervical skin outlines was better with MRI.
Conclusions: MRI proved to be a valuable supplementary method to ultrasound in obtaining accurate information from the fetal neck, pharynx and posterior fossa, particularly when acoustic shadowing by bony structures or adjacent malformation impaired the quality of the ultrasonographic examination.