Comparison of prenatal and postnatal MRI findings in the evaluation of intrauterine CNS anomalies requiring postnatal neurosurgical treatment

To assess the diagnostic capability of fetal magnetic resonance imaging (MRI) in children suspected antenatally to harbor central nervous system (CNS) defects that require immediate postnatal neurosurgical treatment.

Between 2003 and 2005, 13 fetal MRI scans were performed in mothers suspected to have fetuses with congenital CNS defects that would require surgery soon after birth. Comparisons between antenatal and postnatal scans were made with emphasis on diagnostic accuracy of antenatal examinations.

All mothers were scanned using heavily T2-weighted fat-saturated sequences, allowing rapid acquisitions to avoid movement artefacts. Imaging quality was satisfactory in all patients. Diagnoses made antenatally were: myelomeningocele in seven, meningocele in one, diastematomyelia in one, occipital meningocele in one, and isolated hydrocephalus in three children. Of the seven children with antenatal diagnosis of myelomeningocele, one proved to have spinal lipoma postnatally. The patient who antenatally was diagnosed with meningocele proved to have spinal lipoma postnatally. These two were early antenatal MR scans. Antenatal diagnosis of hydrocephalus was made in five of the six confirmed myelomeningocele patients, which was verified postnatally. Antenatal diagnosis of Chiari II malformation was made in all six confirmed myelomeningocele patients. The antenatal diagnoses of occipital meningo-encephalocele and isolated hydrocephalus were verified postnatally. Antenatal diagnosis of diastematomyelia was not verified postnatally.

Fetal MRI scanning is an effective, noninvasive method of assessing in-utero CNS abnormalities. The diagnostic accuracy has improved to allow prediction of clinical outcome and counseling for possible treatment, but is not perfect yet to allow counseling for termination of pregnancy.