OBJECTIVE:

To describe and compare all cases with central nervous system defects evaluated prenatally with structural ultrasound and magnetic resonance imaging.

MATERIALS AND METHODS:

Case series, retrolective, based on the records of the Structural Defects Clinic. Inclusion criteria: fetuses with central nervous system defects. Structural revisions were collected from the clinical record and reported MRI findings. Comparisons between the findings of the two methods were established, considering the final diagnoses established after birth.

RESULTS:

Fifty-eight cases were analyzed; in 34 cases the MRI and ultrasound findings were the same. In 12 cases the MRI provided additional information and in another 12 cases the diagnosis changed. Neural tube defects and midline malformations had the highest incidence (n = 13 of each). Ultrasound had the highest failure rate for cortical formation anomalies and destructive lesions (29 and 33, respectively).

CONCLUSIONS:

Prenatal MRI is a complementary tool to ultrasound that is useful in the evaluation of central nervous system abnormalities, primarily cortical alterations. Ultrasound and MRI have strengths and limitations; each performs better in different aspects of the structural evaluation of the central nervous system. So far there is insufficient evidence to pinpoint the superiority of one over the other.